[tt] New Scientist: Instant Expert: Human Evolution

[Premise Checker]

I have a longer compilation on human evolution and another one on the 
human brain. They are too long for lists and will send them separately to 
anyone who asks.

Special Report on Human Evolution
http://www.newscientist.com/channel/being-human/human-evolution/dn9990

EXPERT GUIDE

The incredible story of our evolution from ape ancestors spans 6
million years or more, and features the acquirement of traits from
[92]bipedal walking, [93]large brains, [94]hairlessness,
[95]tool-making, [96]hunting and [97]harnessing fire, to the more
recent development of [98]language, [99]art, [100]culture and
[101]civilisation.
Darwin's The Origin of Species, published in 1859, suggested that
humans were descended from African apes. However, no fossils of our
ancestors were discovered in Africa until 1924, when [102]Raymond
Dart dug up the "[103]Taung child" - a 3-million to 4
million-year-old Australopithecine.
Over the last century, many spectacular discoveries have shed light
on the history of the human family. Somewhere between 12 and 19
different species of early humans are recognised, though
palaeoanthropologists bitterly dispute [104]how they are related.
Famous fossils include the remarkably complete "Lucy", dug up in
Ethiopia in 1974, and the astonishing "hobbit" species, [105]Homo
floresiensis, found on an Indonesian island in 2004.

[106]more...
[107]Timeline
[108]Timeline

[109]Pick of the Archive
[111]Web Links
[113]Bookworm
[115]Infrequently asked questions

References

92. 
http://www.newscientist.com/channel/being-human/human-evolution/dn6353-human-ancestors-quickly-found-their-feet.html
93. 
http://www.newscientist.com/channel/being-human/human-evolution/dn9767-fastestevolving-human-gene-linked-to-brain-boost.html
94. 
http://www.newscientist.com/channel/being-human/human-evolution/dn3807-early-humans-lost-hair-to-beat-bugs.html
95. 
http://www.newscientist.com/channel/being-human/human-evolution/dn8464-did-humans-colonise-north-europe-earlier-than-thought.html
96. 
http://www.newscientist.com/channel/being-human/human-evolution/dn9091-humans-back-in-frame-for-ancient-horse-extinction.html
97. http://www.newscientist.com/channel/being-human/human-evolution/dn4944
98. 
http://www.newscientist.com/channel/being-human/human-evolution/dn2678-gene-study-gives-language-lesson.html
99. 
http://www.newscientist.com/channel/being-human/human-evolution/dn4256-weird-rock-carvings-puzzle-archaeologists.html
100. 
http://www.newscientist.com/channel/being-human/human-evolution/dn9392-ancient-beads-imply-culture-older-than-we-thought.html
101. 
http://www.newscientist.com/channel/being-human/human-evolution/mg18324655.500-born-to-trade.html
102. 
http://www.newscientist.com/channel/being-human/human-evolution/mg12216626.300.html
103. 
http://www.newscientist.com/channel/being-human/human-evolution/mg14719940.800-taung-child-fell-from-the-sky.html
104. 
http://www.newscientist.com/channel/being-human/human-evolution/mg17623665.300-who-are-we.html
105. 
http://www.newscientist.com/channel/being-human/human-evolution/mg18424711.000
106. 
http://www.newscientist.com/channel/being-human/human-evolution/dn9990
107. 
http://www.newscientist.com/channel/being-human/human-evolution/dn9989-timeline-human-evolution.html
108. 
http://www.newscientist.com/channel/being-human/human-evolution/dn9989-timeline-human-evolution.html
109. http://www.newscientist.com/guide/human-evolution/archive
111. http://www.newscientist.com/guide/human-evolution/weblinks
113. http://www.newscientist.com/guide/human-evolution/bookworm
115. http://www.newscientist.com/guide/human-evolution/lastword

Human ancestors quickly found their feet
http://www.newscientist.com/channel/being-human/human-evolution/dn6353-human-ancestors-quickly-found-their-feet.html
* 19:00 02 September 2004
* Jeff Hecht

Hominids started walking on two legs six million years ago, shortly
after diverging from chimpanzees, according to a study of the inner
structure of a fossilised thighbone. The finding puts upright
posture at the base of the human family tree.

The evolution of upright posture is a key issue in anthropology.
Together with large brain size, it marks the dividing line between
humans and the great apes.

Researchers know that upright posture evolved first because the
skeleton of famed Australopithecine, Lucy, has a small braincase but
modern ankles. Yet with few known fossils older than about four
million years, the details of how and when upright posture evolved
have been hazy. Over the past few years, however, two important new
finds have begun to fill in the gaps.

The older animal is Sahelanthropus tchadensis, which lived in Chad
six to seven million years ago, but only its hominid cranium was
found. More complete is the chimpanzee-sized Orrorin tugenensis, as
20 fossils from at least five individuals have been found in Kenya.
These are about six million years old.

A team led by Brigitte Senut of the French Museum of Natural History
in Paris initially classed Orrorin as a hominid, on the human side
of the split from chimpanzees. This classification was based on
skeletal features, but other anthropologists remained sceptical.

Horizontal beam

To address those doubts, Robert Eckhardt of Pennsylvania State
University in the US carried out a CT scan on the most complete of
Orrorins three thighbones. He hoped that revealing its internal
structure would indicate the biomechanical use of the bone.

The critical part of each thighbone which consists of a strong outer
cortex and a spongy core is the neck shaft that connects the top
part of bone with the hip joint. Essentially, the thighbones are
supporting a horizontal pelvic beam that takes the weight of the
head and body. The precise load this places on the thighbones
depends on body posture, and this determines the musculature and
structure of the thighbones.

In knuckle-walking chimps, the cortex is the same thickness on the
top and bottom of the bone. However, bipedal, upright walking
applies different forces, which means the cortex in humans is at
least four times thicker on the bottom part of the bone.

Fossilisation usually obscures the internal structures of bones, so
"there aren't many hominids in which scanning will work", Eckhardt
told New Scientist.

However, with Orrorin he was lucky. He and a research group
including Senut found that the lower part of the thighbone in
Orrorin is three times thicker than the upper - making its walking
habits much closer to humans than chimps.

Journal reference: Science (vol 305, p 1450)

There is 1 comment on 1 page
Hello
By Me
Fri Feb 22 02:39:30 GMT 2008
This boring!

Fastest-evolving human gene linked to brain boost
http://www.newscientist.com/article.ns?id=dn9767&print=true

* 18:00 16 August 2006
* Gaia Vince

The fastest evolving gene in the human genome is one linked to brain
development, researchers say.

A study of differences between the human and chimp genomes has
identified a gene associated with neural growth in the cerebral
cortex the part of the brain involved in processing thoughts and
learning as having undergone accelerated evolutionary change.

Katherine Pollard and colleagues at the University of California
Santa Cruz, US, suggest that the fast-changing gene may help explain
the dramatic expansion of this part of the brain during the
evolution of humans.

They identified the rapidly evolving region of DNA called human
accelerated region 1 (HAR1) after carrying out an extensive
computational comparison between the genomes of humans, chimpanzees
and other vertebrates.

Critical role

There are only two changes in the 118 letters of DNA code that make
up HAR1 between the genomes of chimps and chickens. But chimps and
humans are 18 letter-changes apart. And those mutations occurred in
just five million years, as we evolved from our shared ancestor.

That is an incredible amount of change to have happened in a few
million years, Pollard notes.

Subsequent experiments looking at the brains of human and primate
embryos revealed that HAR1 is part of two overlapping genes. One of
these genes, called HAR1F is active in nerve cells that appear early
in embryonic development and play a critical role in the formation
of the layered structure of the human cerebral cortex.

The role of the other gene, called HAR1R, is less clear, but it also
appears also to be involved in cortex development.

"Very suggestive"

The researchers point out that these genes do not appear to code for
any proteins, but are what is known as an RNA genes.

We dont know exactly what it does, but the evidence is very
suggestive that HAR1F is important in the development of the
cerebral cortex, and thats exciting because the human cortex is
three times as large as it was in our predecessors, says David
Haussler, director of the Center for Biomolecular Science and
Engineering at the University of California Santa Cruz, who assisted
with the study.

Something caused our brains to evolve to be much larger and have
more functions than the brains of other mammals, he points out.

Journal reference: Nature (DOI: 10.1038/nature05113)

The Human Brain - With one hundred billion nerve cells, the
complexity is mind-boggling. Learn more in our cutting edge special
report.

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* Fast language learners boast more white matter
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* Consciousness: because you're worth it
* http://www.newscientist.com/article.ns?id=mg19025572.600
* 24 June 2006
* Are we still evolving?
* http://www.newscientist.com/article.ns?id=mg18925421.300
* 11 March 2006

Weblinks

* Nature
* http://www.nature.com/index.html
* University of California Santa Cruz, US
* http://www.ucsc.edu/public/

Early humans lost hair to beat bugs
http://www.newscientist.com/article.ns?id=dn3807&print=true

* 00:01 08 June 2003
* Shaoni Bhattacharya

Humans may have lost their body hair to reduce their vulnerability
to fur-loving parasites and therefore attract the opposite sex, a
new evolutionary theory proposes.

The nakedness of the human species is extremely rare among the 3000
or so living mammal species. Other naked mammals include elephants,
walruses, pigs, whales and the bizarre naked mole-rat.

A widely accepted view is that humans lost their hair to help
control their body temperature as they evolved into upright
creatures on the warm plains of the African savannah. But this
theory has problems that researchers believe the new theory can
solve.

"The body cooling hypothesis is interesting, but some of the
advantages in not having fur in the Sun become disadvantages at
night," says Pagel, an evolutionary biologist at the University of
Reading, UK. Humans would lose too much heat at night, he says.

"In animals, ectoparasites like biting flies, exert tremendous
fitness costs - they really affect our health," he told New
Scientist. "Our view is that hairlessness is an adaptation for
reducing the ectoparasite load."

Warmth and shelter

However, if humans evolved to beat parasites by losing the hair they
hide in, why did our hirsute ape cousins not do the same? The
reason, says Pagel, is that we also developed our own culture. We
are the only ones who learned to build fires and shelter and to make
clothes, he says, all of which helped us keep warm while shedding
our fur.

"It's one of those nice cases of gene/culture co-evolution," says
Pagel. "It's the culture which helped us acquire the means to lose
our hair."

"It does sound quite plausible," agrees Christophe Soligo, a
researcher in human origins at the Natural History Museum in London,
UK. Soligo calls the theory "elegant" as it addresses a key problem.

"The question we always have in explaining unique human traits is:
why didn't other animals evolve them as well if they are so
advantageous?" he told New Scientist.

Sexual selection

The only other animal that has achieved something similar is the
naked mole rat. These strange sausage-like creatures live
underground in large social colonies in arid regions. In their
densely populated networks they should suffer a huge parasite load,
but they do not. Their nakedness is possible as the temperature of
their underground tunnels is very even.

Sexual selection for desirable mates may be another pressure which
fuelled hair loss in humans, suggest Pagel and his colleague Walter
Bodmer at the University of Oxford, UK.

Pagel says natural selection might initially favour less hairy
individuals, as they have fewer parasites. But sexual selection
could accelerate the loss of fur, as more naked early humans could
be fitter and therefore more attractive as mates.

The researchers say one way to test their theory would be to see
whether humans who live in areas with large parasite populations are
less hairy than those who do not.

Journal reference: Biology Letters (Online publication)

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* 29 May 2003
* Neanderthals as nimble-fingered as humans
* http://www.newscientist.com/article.ns?id=dn3555
* 27 March 2003
* Tadpoles take blame for human hiccups
* http://www.newscientist.com/article.ns?id=dn3355
* 5 February 2003

Weblinks

* Mark Pagel, Reading University
* http://www.ams.rdg.ac.uk/zoology/pagel/
* Natural History Museum, London, UK
* http://www.nhm.ac.uk/index.html
* Biology Letters
* http://www.pubs.royalsoc.ac.uk/biol_lett/biol_lett.html

Did humans colonise north Europe earlier than thought?
http://www.newscientist.com/article.ns?id=dn8464&print=true

* 18:00 14 December 2005
* Rowan Hooper

Humans may have colonised northern Europe 200,000 years earlier than
previously thought. Stone tools found in eastern England suggest
that humans were there at least 700,000 years ago.

"We don't know for sure what species it was," says team member Chris
Stringer of the Natural History Museum in London, "but my bet is
it's an early form of Homo heidelbergensis or Homo antecessor."

H. heidelbergensis is known to have been present in central Europe
about 500,000 years ago. Bones were first discovered in 1907 near
Heidelberg, Germany, and have since been found in France and Greece.
Hominin remains about 800,000 years old have been found in Spain and
Italy, indicating that early humans had colonised southern Europe by
this time. These early humans have been classed as another species,
H. antecessor, though arguments remain over whether it is a really
separate species to H. heidelbergensis.

The 32 stone tools, made of black flint and many of them still
sharp, were discovered by amateur archaeologists at Pakefield,
Suffolk. They have been dated using several methods. Firstly, the
magnetic polarity of iron-containing minerals in the sedimentary
rocks where the tools were found is aligned north-south, just as it
is today. The Earth's magnetic field underwent a polarity reversal
780,000 years ago, so the site must be younger than that.

The tools were found beneath glacial deposits laid down during a
period 450,000 years ago when the region was blanketed in ice, so
they must be older than this. Also present were fossils of a water
vole Mimomys, which was superseded by another vole species called
Arvicola around 500,000 years ago. This leads the authors to
speculate that the tools are around 700,000 years old.

A new amino-acid dating technique developed by Kirsty Penkman of the
University of York in the UK supports this estimate. The method was
used to measure the breakdown of amino acids within shells of a
freshwater snail found at the site (Nature, vol 438, p 1008).

Back then Britain was connected to what is now the European mainland
and had a climate similar to that of the Mediterranean today. The
researchers found hippo fossils at the Pakefield site, as well as
fossils of other warmth-loving species such as lion, an extinct
giant deer called Megaloceros dawkinsi and Palaeoloxodon antiquus,
an extinct straight-tusked elephant. Rhinos and hyenas also roamed
the region.

The warm climate probably allowed early humans to migrate northwards
without the need to develop technology such as fire and clothing or
to adapt to a colder climate, says Anthony Stuart of University
College London, who coordinated the project.

But the climate got the better of them eventually. "People couldn't
settle here long-term," says Stringer. "They would have been swept
away by the cold stage that followed about 100,000 years ago."

Humans back in frame for ancient horse extinction
http://www.newscientist.com/article.ns?id=dn9091&print=true
* 11:26 02 May 2006

Humans are back in the frame as suspects in the extinction of
ancient horses in Alaska thousands of years ago.

Previous dating of the youngest fossils indicates the horses
disappeared about 500 years before the arrival of humans from Asia.
But a new statistical analysis of the fossil dates suggests the
animals actually went extinct a few hundred years after humans
turned up.

The end of the Pleistocene epoch saw extinctions of many large
animals, including mammoths and caballoid horses in North America
and elsewhere. Exactly what caused some these extinctions remains
open for debate. But experts consider climate change and human
hunting two of the most probable explanations.

The most recent mammoth fossil from Alaska dates to 11,500 years
ago, according radiocarbon dating. Researchers have similarly found
that the youngest ancient horse fossil there is about 12,500 years
old.

But this new statistical analysis assumes that palaeontologists have
yet to find the most recently dead horse fossils in Alaska, says
Andrew Solow of the Woods Hole Oceanographic Institution in Woods
Hole, Massachusetts, US.

Random sampling

Solow and his colleagues gathered information about the dating of
the 24 most recent ancient horse fossils.

Assuming the fossils found by palaeontologists represent a random
sampling of all the fossils in the rocks, a statistical analysis of
the distribution of the known dates suggests that there are as yet
undiscovered horse fossils from more recent times. The errors
associated with fossil dating itself were also considered in the
statistical model. Researchers stress that the accuracy of
radiocarbon dating varies depending on factors such as the quality
and size of the fossil sample.

The new analysis reveals that the ancient horses of Alaska could
have persisted until perhaps 11,700 years ago. As humans are thought
to have arrived around 12,000 years ago in the same region, this
provides support for the idea that they could have played a role in
the disappearance of these creatures.

Solow adds that a similar statistical approach has been used in
other areas, such as sports. Mathematicians use the method to infer
the longest distance that athletes could possibly throw an object,
based on known records. Such analyses provide some evidence that
extraordinary performances may be the result of doping.

Journal reference: Proceedings of the National Academy of Sciences
(DOI: 10.1073/pnas.0509480103)

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* The very first Americans
* http://www.newscientist.com/article.ns?id=mg19025461.400
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* http://www.newscientist.com/article.ns?id=mg18925421.900
* 11 March 2006
* Elephants and lions unleashed on North America?
* http://www.newscientist.com/article.ns?id=dn7862
* 17 August 2005

Weblinks

* Pleistocene Epoch, Encyclopaedia Britannica
* http://wwwa.britannica.com/eb/article-9117455
* Proceedings of the National Academy of Sciences
* http://www.pnas.org/

Charred remains may be earliest human fires
http://www.newscientist.com/article.ns?id=dn4944&print=true

* 19:00 29 April 2004
* James Randerson

Archaeologists in Israel may have unearthed the oldest evidence of
fire use by our ancestors.

The site, on the banks of the Jordan River, dates to about 790,000
years ago. There are older sites in Africa, but the evidence from
these is much more hotly contested.

The moment that our ancestors discovered how to control fire has
long occupied an iconic place in the popular imagination.
Chimpanzees, our closest living ancestors, have demonstrated
impressive feats of language and tool use, but fire use "is the most
human skill that we have", says Nira Alperson an archaeologist at
the Hebrew University of Jerusalem.

Finding direct evidence for ancient fire use is extremely difficult
and the new study is applauded by Derek Roe an archaeologist at
Oxford University, UK: "Any small fact you can find is a great
triumph."

Ancient hearths

The oldest indications of fire use come from Koobi Fora in Kenya
where researchers found patches of discoloured sediment. But
suggestions that these were 1.6-million-year-old hearths have failed
to convince many researchers.

Now Alperson and colleagues have found compelling, although not
conclusive, evidence that one of our ancestors was using fire
790,000 years ago at Gesher Benot Ya'aqov. By comparison, the oldest
evidence of fire control in Europe dates from around 500,000 years
ago.

The team analysed over 50,000 pieces of wood and nearly 36,000
pieces of flint from what was once probably a Homo erectus
settlement on the shores of an ancient lake. Flint was examined
because it was used for tool making and shows a characteristic
pitting when exposed to fire.

Many of the burnt specimens were clustered in two patches, which the
team believe were ancient hearths. They also point out the low
proportion of burnt remains - only around four per cent of the wood
and two per cent of the flint. "If a natural fire had caused it we
would have expected a higher percentage to be burned," says
Alperson.

Test fire

But Sally McBreaty, an anthropologist at the University of
Connecticut in Storrs, is not convinced. She says it would have been
good to see the team set up an experimental brush fire and measure
what proportion of wood and flint in the undergrowth ended up being
burnt.

Everyone agrees on the impact that fire would have had on our
ancestors though. "We know for sure that it dramatically changed
their lives," says Alperson.

Fire-starters would have been able to migrate to colder regions,
drive away predators, get more energy from food by cooking it and
enjoy a more cohesive social life.

However, finding out more from the site at Gesher Benot Ya'aqov may
never be possible. In 1999, after the samples used in Alperson's
study were collected, the local drainage authority destroyed a large
chunk of the site.

Journal reference: Science (vol 304, p 725)

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* 8 April 2004
* Early humans swapped bite for brain
* http://www.newscientist.com/article.ns?id=dn4817
* 24 March 2004

Weblinks

* The Hebrew University of Jerusalem
* http://www.hum.huji.ac.il/archaeology/
* The destruction of Gesher Benot Ya'aqov
* http://www.hum.huji.ac.il/archaeology/GBY/english.htm
* Koobi Fora, National museums of Kenya
* http://www.museums.or.ke/psmkoobi.html
* Science
* http://www.sciencemag.org

Gene study gives language lesson
http://www.newscientist.com/article.ns?id=dn2678&print=true

* 19:00 14 August 2002
* James Randerson

Two mutations in a human language gene have been strongly selected
for over the past 200,000 years, new research shows. The finding
provides evidence for the idea that language spread by giving a
major survival or mating advantage to those who possessed it, and
that it is not merely a handy by-product of big brains.

People with a faulty copy of the FOXP2 gene have problems applying
grammatical rules and coordinating their mouth and tongue to
articulate words. The gene's sequence suggests it switches on other
genes, but researchers do not know which ones.

Now Svante Pääbo at the Max Planck Institute for Evolutionary
Anthropology in Leipzig and colleagues have sequenced chimp,
gorilla, mouse, rhesus macaque and orangutan versions of FOXP2, in
order to study its evolution.

Remarkably, there are only three changes between the human and mouse
proteins. But two of these happened after the split between humans
and chimps. And the new analysis of nearby DNA suggests these
mutations spread rapidly and recently in humans.

"We have no idea how those changes were linked to language ability,"
admits Oxford University's Tony Monaco, who discovered FOXP2 and is
also part of the team. However, Pääbo speculates that the changes
allowed our ancestors to improve on rudimentary communication.

Global spread

Steven Pinker, a language expert at the Massachusetts Institute of
Technology says the team's analysis refutes the idea that language
is merely a handy by-product of having a large brain. "It suggests
that language is an adaptation, a product of natural selection," he
told New Scientist.

To uncover evidence of selection, the team looked in more detail at
the gene in 226 humans from across the globe. In particular, they
compared the intron sequence located next to the two mutations. This
sequence is a chunk of DNA that is cut out before the message is
translated into protein.

If the global spread of the two mutations had happened five million
years ago, shortly after our ancestors split from early chimpanzees,
some intron mutations would be widely shared. But the analysis
showed multiple rare mutations in the sequences.

The researchers conclude that the two mutations spread rapidly at
some point in the past 200,000 years.

Pinker believes the analytical approach used is powerful: "It's not
an idle just-so story to say that something is a product of
selection." The work demonstrates that the two mutations were rushed
through the population because they conferred a considerable
advantage, he says.

Journal reference: Nature (DOI: 10.1038/nature01025)

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* 29 August 2001

Weblinks

* Evolutionary genetics, Max Planck Institute, Leipzig
* http://www.eva.mpg.de/genetics/
* Speech and genes, Oxford University
* http://www.well.ox.ac.uk/monaco/spch1cecilia.shtml
* Steven Pinker
* http://www.mit.edu/~pinker/
* Nature
* http://www.nature.com/nature/

Weird rock carvings puzzle archaeologists
http://www.newscientist.com/article.ns?id=dn4256&print=true

* 17:34 09 October 2003
* Shaoni Bhattacharya

Mysterious rock carvings engraved into strange shapes are baffling
UK archaeologists. One resembles a heart, another a human footprint.

Aron Mazel and Stan Beckensall, who stumbled across the unusual
carvings close to England's border with Scotland, believe they are
the first such designs to have been discovered in the UK.

"We have absolutely no idea what they are," says Mazel, an
archaeologist at the University of Newcastle. "They are nothing like
anything we, or anybody else we have talked to, have seen before."
He believes the carvings were not created recently - in the last 15
to 20 years - and could be as ancient as 3000 years old.

The researchers were alerted to the etchings on an isolated boulder
by a farm worker, while they were investigating the well-known "cup
and ring" rock art in Northumberland. These prehistoric etchings
have been found across the UK, and are particularly abundant in the
county.

Stone pick axes

"The carvings we have found before - cup and ring - dated back to
the Neolithic Bronze Age and were probably done by early farmers,"
Mazel told New Scientist. They were hacked into rock faces using
stone pick axes.

But the new-found carvings are "very different", he says. "They are
sharper on one hand, but also quite smooth." Metal tools are likely
to have been required to make them.

"Also, the imagery reflected in the carvings are very different,"
Mazel says. "They are elliptical shapes, and something which looks
like a footprint, and a heart."

Mazel and Beckensall are puzzled by their discovery and have
consulted experts in the field such as English Heritage, but no one
has been able to shed any light.

"We are keen to draw people's attention to them - seeing the
pictures of the markings may prompt somebody to come forward with
new information, perhaps relating to similar rock art samples they
have viewed elsewhere," says Beckensall.

Related Articles

* Doubt cast on age of oldest human art
* http://www.newscientist.com/article.ns?id=dn3631
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* Animal-headed humans appear in earliest art
* http://www.newscientist.com/article.ns?id=dn1590
* 21 November 2001
* Ancient cave etchings reveal unusual figures
* http://www.newscientist.com/article.ns?id=dn977
* 5 July 2001

Weblinks

* Aron Mazel, University of Newcastle
* http://historical-studies.ncl.ac.uk/people/aron_mazel/
* Northumberland rock art project
* http://historical-studies.ncl.ac.uk/research/projects/project_34
/index.htm
* Rock Art
* http://myweb.tiscali.co.uk/celynog/neolithic_carving.htm

Ancient beads imply culture older than we thought
http://www.newscientist.com/article.ns?id=dn9392&print=true

* 19:00 22 June 2006
* Anna Gosline

Archaeologists have discovered that 100,000-year-old shells found in
Israel and Algeria were decorative beads. This suggests that modern
human forms of behaviour, such as language, developed earlier than
previously thought.

"Personal ornaments are a powerful tool of communication," says
Francesco DErrico at the Institute of the Prehistory and Geology of
the Quaternary in Talence, France, one of the team that studied the
beads. "They can indicate social or marital status, for example. But
you need to have a complex system of language behind that. To me
[these beads] are very powerful archaeological evidence that these
people were able to speak like us."

In 2004 archaeologists unearthed 41 pea-sized shell beads in Blombos
Caves, South Africa, dated at 75,000 years old. The shells were all
punctured in the same place and showed signs of wear, as if they had
been strung together. They were the oldest record of personal
ornamentation ever found, suggesting that African humans from this
time could think symbolically and were more culturally advanced than
previously believed.

That find prompted Marian Vanhaeren at University College London and
her colleagues to take a further look at shells mentioned in site
excavation logs from Skhul in Israel and Oued Djebbana in Algeria.
The team found three shells of the ocean gastropod Nassarius
gibbosulus in museums in London and Paris. Two were from Skhul,
dating from at least 100,000 years ago, and one was from Oued
Djebbana and between 35,000 and 90,000 years old. The snail is of
the same genus as those found in the Blombos Caves, and all the
finds were too tiny to be collected as food. Each shell had a hole
on the back, most likely punctured by humans, though such holes do
occur naturally.

Shell traders

For the past 100,000 years Skhul and Oued Djebbana have been 20 and
190 kilometres respectively from the sea, where the snails live.
"These beads needed to have been collected or traded, which implies
that they had cultural value," says Bernard Wood at George
Washington University in Washington DC, US. "You wouldnt trudge 200
kilometres if you could find something a lot more local."

The finding is more evidence that modern human behaviour developed
gradually in Africa following the appearance of anatomically modern
humans around 200,000 years ago. The conventional archaeological
wisdom, however, states that culturally modern humans appeared
suddenly in Africa or Eurasia just 40,000 years ago, in what is
known as the "human revolution". This conclusion was based on the
rich archaeological sites in Europe dated from that time, filled
with a plethora of engravings, sculpture, beads and artworks.

"That sort of prejudice is being continually eroded with these kinds
of discoveries," says Wood. "But it still raises the question, in
order to make holes in beads and to have the need for beads, does
that mean you have language? Bead-making is being used as a proxy
for modern human behaviour. It would be nice if there were more
proxies and it would be nice to find them at these sites."

But Sally McBrearty at the University of Connecticut in Storrs, US,
says that one artefact is enough. "In European sites all of these
symbolic artefacts appear together in a package. But even one of
these things shows the capacity for symbolic communication. You find
them all together in Europe because it was many tens of thousands of
years after they were invented in Africa."

Journal reference: Science (vol 312 p 1785)

Related Articles

* Born to trade
* http://www.newscientist.com/article.ns?id=mg18324655.500
* 18 September 2004
* Ancient shell jewellery hints at language
* http://www.newscientist.com/article.ns?id=dn4892
* 16 April 2004
* Ostrich beads indicate early symbolic thought
* http://www.newscientist.com/article.ns?id=dn4839
* 31 March 2004

Weblinks

* Institute of the Prehistory and Geology of the Quaternary
* http://www.ipgq.u-bordeaux1.fr/Pages/home.html
* Marian Vanhaeren, University College London
* http://www.ucl.ac.uk/cecd/people/?go1=63
* Bernard Wood, George Washington University
* http://home.gwu.edu/~bwood/
* Sally McBrearty, Unniversity of Connecticut
* http://www.anth.uconn.edu/faculty/mcbrearty/
* Science
* http://www.sciencemag.org

Born to trade
http://www.newscientist.com/article.ns?id=mg18324655.500&print=true

* 18 September 2004
* Kate Douglas

IT'S Saturday afternoon at the mall, and worshippers at the shrine
of consumerism are out in force. They throng the aisles, queuing at
the checkouts and standing in line at the fast food altars. There is
a low-level hum of voices, as if in prayer. Tills ring out as they
open to receive donations of coins and notes, or the more intangible
tithe of credit cards. Every weekend the same ritual is played out
across the developed world. Millions of people spend-spend-spending
money they often have yet to earn on goods they don't really need.
Is this the apogee of human civilisation?

Hardly. It is becoming increasingly clear that our obsession with
material goods is very ancient indeed. Mass consumerism may be a
20th-century invention, but its roots go back to the dawn of
humanity. It is arguably the cornerstone of civilisation. Before our
ancestors invented writing, before they had laws and cities, before
pastoralism and farming, even before the use of metal to make tools,
there was trade.

Trade in the necessities of life such as food and simple tools is
probably at least as old as our species. But what is really
surprising is that our taste for objects with no obvious survival
value - trinkets, luxury items and "prestige goods" - also goes way
back. Recent finds in Africa suggest that decorative objects were
being manufactured and traded more than 100,000 years ago. And some
researchers are now proposing that our desire for material objects
might have been what launched our ancestors on the long road to
modernity.

Humans are born to trade. And we don't need shops or money to do it
- the heart of commerce is an instinctive talent for what
anthropologists call "reciprocity". This probably evolved as the
brains of our hominid ancestors grew and their societies became more
complex, allowing individuals to keep a running tally of their
interactions with others. Evidence from modern hunter-gatherers
leaves little doubt that the exchange of food and favours comes
naturally, as does the ability to keep a tab of the credits and
debits that accrue as a result. Combine this aptitude for mental
book-keeping with even the most basic material culture, and trade
inevitably follows.

Barter power

Once trade gets off the ground, the economic benefits quickly make
it irresistible. Take the Yir Yoront aboriginals of Cape York in
northern Australia. Until the latter part of the 20th century they
were true hunter-gatherers with few of the trappings we equate with
civilisation, yet they did have a lively trading relationship with
their neighbours.

The Yir Yoront formed one link in a chain of exchange that stretched
from the coast, where they and other local groups produced stingray
barbs for fishing, via a succession of trading partners to a site
400 miles inland where the residents quarried and produced polished
stone axes. The relative value of stingray barbs increased in direct
proportion to the distance from the sea, while the value of axes
increased the further they moved from the quarry. So, simply by
exchanging the more highly prized items for the less valuable ones,
every individual along the chain could make a profit in the form of
barbs and axes, even if he produced neither.

It is a short leap from the Yir Yoront to imagining Stone Age people
in regions where certain objects were abundant trading these items
in regions where they were scarce. But it doesn't even require
patchily distributed resources to make trade profitable. British
economist David Ricardo formulated this idea in 1817 in his law of
comparative advantage. In essence, what this says is that it
benefits two parties to trade even if both can produce their own
barbs and axes, and even if one can produce both more efficiently
than the other party. That's because both good manufacturers and
poor ones will be better off concentrating their production on the
item they can produce more efficiently and trading these for things
they are less efficient at producing. By doing this they will get a
better payback for their efforts and everybody gains.

But even if our Stone Age ancestors were exchanging tools, food and
other essentials of life in a barter economy, this is a far cry from
the shopping mall. Modern consumerism goes way beyond subsistence
and utilitarianism to encompass everything from Gucci handbags and
BMW convertibles to impressionist paintings and designer "bling".
Clearly, the value of such goods is not inherent but resides in
certain intangible qualities that we invest in them. When did humans
start attributing such value to objects?

Until recently all the archaeological evidence for the flowering of
consumer culture has pointed to a date of around 40,000 years ago.
That's when early modern humans started making increasingly
intricate bone and stone tools, carving patterns into rocks and
creating representational art such as carved figurines, jewellery
and cave paintings. However, as most of these artefacts come from
sites in Eurasia - notably a set of 41,000-year-old shell beads from
Üçagizli in Turkey - there have been suggestions that this is not
the full picture. Discoveries in Africa now seem to confirm this and
are pushing the origins of consumerism much further back into human
prehistory.

A few years ago, reports began to emerge of discoveries made at the
Blombos cave, a site of ancient human habitation 300 kilometres east
of Cape Town in South Africa. Christopher Henshilwood from the
University of Bergen in Norway and colleagues described finding
thousands of pieces of ochre, many of them more than 100,000 years
old - before the time that early humans moved out of Africa.

Ochre, a coloured clay that comes in various earthy shades from red
to black, does not occur naturally around Blombos and must have been
imported from quarries at least 30 kilometres away, either directly
by Blombos residents or through trade. It can be used to cure animal
hides, but the researchers are convinced the Blombos ochre had a
symbolic purpose. For a start, it is predominantly red - any of the
other colours available would have done for curing - and the
surfaces of the clay have been scraped in a way that indicates they
were used to yield pigment for dyes. Henshilwood's team suspects the
dyes were used for ritual cosmetic purposes to colour hides and
human skin, just as they still are in the region today.

In 2002, Henshilwood and colleagues dated two particularly
impressive pieces of Blombos ochre at 77,000 years old - the middle
stone age (Science, vol 295, p 1278). The abstract, cross-hatched
designs on these have led some observers to dub them the oldest
works of art. Henshilwood is more circumspect, but he points to a
growing body of evidence for widespread ochre use in Africa dating
back 120,000 years. "The Blombos finds are but a blip in an emerging
symbolic ocean that is the middle Stone Age," he says.

Earlier this year the team announced an even more intriguing
discovery from Blombos - 41 beads dating from 76,000 years ago
(Science, vol 384, p 404). The beads, which were found in clusters
of between 2 and 17, are made from the shells of a tiny mollusc,
Nassarius kraussianus, that lived in estuaries 20 kilometres away.
These cannot be natural deposits, argue the researchers, as each
cluster contains shells of a similar size and colour with
consistently placed holes. What's more, all the beads display a
pattern of wear suggesting friction from rubbing against thread,
clothes or other beads. There are also traces of red ochre inside
the shells. The previous oldest find of beads in Africa dates back
to just 45,000 years ago.

And it seems the Blombos people's taste for decorative items was not
an isolated phenomenon. In a presentation at this year's
Paleoanthropology Society meeting in Montreal, Canada, Jessica
Thompson of Arizona State University in Tempe described similar
findings from a site in the Loiyangalani river valley in Tanzania.
Along with ochre pencils and carved bone objects, the researchers
found two beads made from ostrich eggshells, along with other
eggshell fragments that they believe may represent debris from bead
manufacture. Although these objects have not been dated accurately,
they were found in association with mid-Stone Age tools, making them
at least 45,000 - and possibly 280,000 - years old. Similar beads
are still made by Khoisan (Bushman) cultures today. Although there
is no evidence of how the ancient beads were used, their modern
counterparts are often traded.

Yet another indicator that material culture was taking hold in
Africa in the Stone Age comes from a ticklish study of lice,
published last year by Mark Stoneking and colleagues from the Max
Planck Institute for Evolutionary Anthropology in Leipzig, Germany
(Current Biology, vol 13, p 1414). On discovering that the lice that
infest our hair are different from the ones that infest our bodies,
Stoneking reasoned that body lice probably evolved from hair lice
when a new ecological niche - clothing - became available. Finding
out when the species diverged would give him a pointer to the
origins of clothing.

To do this, he used the molecular clock method, which ticks off
seconds of evolutionary time by counting the number of genetic
mutations that have arisen in two species since they diverged from a
common ancestor. The results pointed to a date of around 75,000
years ago. This suggests an origin for clothing in Africa before our
ancestors began their mass migration across the globe. "Clothing
could have been a key innovation in allowing our species to move
into colder climates," suggests Stoneking. But some researchers
interpret the finding differently. "It's very likely that the first
clothing would have conferred status and attractiveness on the
wearer," says Geoffrey Miller from the University of New Mexico in
Albuquerque.

So it looks as though our taste for jewellery, art, cosmetics and
fashion is much older than we thought. But why did we come to value
these objects in the first place? One idea is that it was all about
sexual attraction. Miller points out that in many animal species,
individuals signal their genetic fitness by showing off with
expensive adornments. An ostentatious tail that inhibits flight or a
brightly coloured torso that is conspicuous to predators are honest
indicators that you are fit enough to shrug off handicaps. In
humans, consumer products play a similar role, Miller argues.

Archaeologist Aimee Plourde from the University of California, Los
Angeles, takes a similar approach, but shifts the emphasis from sex
to prestige. And her analysis suggests an answer to one of the big
questions about the origin of civilisation - how our ancestors made
the transition from living as egalitarian hunter-gatherers to the
materialistic, hierarchical societies we equate with modern
civilisation.

Plourde argues that even in egalitarian societies, some people are
more successful than others. Among our ancestors, superior skills in
areas such as hunting, crafts, environmental knowledge and contact
with neighbouring groups would have brought respect, deference and
privileged treatment from others - in other words, prestige. And
because prestige brings social benefits, people would want to show
off their talents. The best way to do this is through material items
that are hard to fake. "A good hunter, for instance, could advertise
his skills by wearing the tooth of an animal that is elusive or
dangerous," says Plourde. The benefits of prestige would also lead
to competition to acquire it. As a result, the value and variety of
prestige goods would spiral, and there would be a parallel increase
in the complexity of social ranking systems as individual prestige
led first to leadership of the group and later to the stratified
hierarchies you find in more complex societies.

To test her theory, Plourde has examined archaeological evidence
from a pre-Inca civilisation near Lake Titicaca in highland Peru,
using social developments within this society, which was primitive
until relatively recently, as a model for changes that took place
much earlier elsewhere. She reported her findings in July at the
Human Behavior and Evolution Society conference in Berlin. The site
holds clear archaeological evidence for an increase in social
complexity starting around 2000 BC. It is at this point that you
find the first examples of prestige goods. Certain individuals are
buried with gold and turquoise beads, and one with a gold disc, but
at this stage there are no other signs of status differences between
people. Then, around 700 years later, the villages of the earlier
period are superseded by more sophisticated settlements built around
sunken courts. This indicates the emergence of social ranking, says
Plourde, and is paralleled by an elaboration in prestige goods,
especially decorated stone sculptures and pottery.

Finally, starting around 500 BC, prestige goods become more numerous
and variable in quality. Many of the finer items, including feline
pelts, exotic feathers and hallucinogens such as San Pedro cactus,
were obviously imported from the Amazonian lowlands to the east.
Prestige goods like these would have belonged to the "elite of the
elite", says Plourde, and she believes that these exalted people
limited access to them by controlling trade routes. "Most of the
large sites with civic and ceremonial architecture are in locations
that would have been strategic for monitoring the flow of traffic
through the valley," she says.

If Plourde is correct, prestige goods form a direct link between our
innate drive for trade and the development of complex, hierarchical
societies. They are arguably the first step on the road to modern
civilisation, paving the way for agriculture (p 29) and urbanisation
(p 32).

We may not be impressed by beads, axes and fishing hooks any more,
but their modern equivalents have the same fascination for us.
Nobody believes the guy who spends £670,000 on a Bugatti Veyron does
so because he needs to travel at 250 mph. We all know he's buying an
exclusive status symbol. But don't knock it: he's just being
civilised.
Legacy of the Taung child / Review of 'Raymond Arthur Dart: A Pictorial
Profile' by Frances Wheelhouse
http://www.newscientist.com/article.ns?id=mg12216626.300&print=true

* 29 April 1989
* ROGER LEWIN

Raymond Arthur Dart: A Pictorial Profile by Frances Wheelhouse,
Transpareon Press*, pp 113, A$19.95

I first met Raymond Dart in May of 1984, at the Avery Postgraduate
Institute in Philadelphia, a place he visited yearly to teach about
recovery from brain damage. A frail man of 91 years, Dart was
bending over a reading machine that was displaying the greatly
magnified text of a recent popular book on human origins. 'I didn't
mind being old until my central vision went,' he told me. 'Now I
have to use this thing to read. I feel as if I've lost part of my
life.'

Some 60 years earlier, Dart, who lived in Johnannesburg, had made
the discovery, for which he is most famous. He identified the
fossilised skull of an infant ape-like creature as that of an early
human ancestor. This was the Taung child, Australopithecus
africanus, the first small-brained hominid to be discovered.

The Taung child seems in anatomical harmony with the rest of the
human family tree, a fitting fragment in the mosaic of human
history. But in 1924 the diminutive fossil was alone and quite
dissonant with contemporary views of human origins. For his insight
in suggesting that this little ape-like creature played a
significant role in human evolution Dart was, therefore, scalded,
derided, and finally ignored. Two decades were to pass before his
ideas became accepted as a central part of anthropological thinking.

In recounting this story, Frances Wheelhouse is covering ground
covered many times before. In Raymond Arthur Dart, she reveals no
new insights. Her contribution is in bringing together a large
number of photographs, some of the family-album variety, some
professional, and many of which have not previously been published.
And through these many images of Dart himself comes a real sense of
the energy, the enthusiasm, and most of all, the warmth of the man.

The discovery of the Taung child, and the later fossil work he did,
was just a small part of Dart's many achievements. An Australian,
who had travelled and worked in the US and Europe, Dart went with
great reluctance to live in South Africa in January 1923, there to
establish a department of anatomy at the University of the
Wittwatersrand. His habit of swinging along the pipes in his lecture
hall to demonstrate ape-like brachiation is well remembered by his
students.

Although Wheelhouse alludes to these and many other of Dart's
activities, her short pictorial profile concentrates mainly on the
Taung child and related achievements. Therefore, incomplete as is
the story of Dart's life (Wheelhouse is preparing a full biography),
the book necessarily appeals most to human origins addicts.

Weaving text and pictures together, Wheelhouse begins with Dart's
childhood and goes through to his 90th year, leaving many gaps on
the way. Well-known images, such as Dart with Louis Leakey and with
Robert Broom, are intermixed with seldom seen ones, such as Dart
with the great American palaeontologist William King Gregory. Text
and images for the most part run smoothly together, but occasionally
pictures are out of place in time and seem unrelated to the stage of
the story at hand.

But these are quibbles about what must have been a difficult
enterprise and is certainly a delightful, very personal product. For
those who knew Dart, Wheelhouse's book is a treasure of memories.
For those who knew of him, it is an expanding and confirming
experience. And for those to whom Dart is unknown, it is an unusual
introduction to a most remarkable man.

Dart's life was of many parts, all driven by the fire of his
curiosity and enthusiasm. When his central vision failed late in his
life, it robbed him of part of his sight and much of his fire. When
the flame sputtered low, as it did more and more, he was 'ready to
die', he told me on that May day in 1984. He died last year.

* PO Box 126, Hornsby, New South Wales 2077, Australia.

Roger Lewin is deputy news editor of Science.

Taung Child 'fell from the sky'
http://www.newscientist.com/article.ns?id=mg14719940.800&print=true

* 09 September 1995
* Sue Armstrong

EVER since the fossilised skull of an infant hominid was found at
Taung on the edge of the Kalahari Desert in 1924, scientists have
wondered what the child was doing there and how it died. Despite
exhaustive excavations, no other specimen of Australopithecus
africanus, as the fossil was named, has ever been found at Taung to
indicate that this was a regular hominid haunt. Nor does the
evidence suggest that a carnivore such as a leopard carried off the
child.

Lee Berger and Ron Clarke of the Palaeoanthropology Research Unit at
Witwatersrand University in Johannesburg believe they have found the
answer to the mystery. In the latest edition of the Journal of Human
Evolution they suggest that a large bird of prey such as an eagle
may have killed the child on the nearby plains and carried it off to
its nest.

Their theory, says Berger, explains why precious few fossils of
large antelopes have been found at Taung, which you would expect if
big cats had been responsible. This sets the site apart from other
cave sites in South Africa where hominid fossils have been found.
The fossils at Taung are mainly the small skulls of baboons and
hyraxes, fragments of tortoise carapaces and the shells of large
birds' eggs.

The Taung Child, discovered by Raymond Dart, was the first fossil of
a human ancestor found in Africa. It provided the first concrete
evidence that this continent, not Asia, was the cradle of humankind.

The idea that the child could have fallen prey to a large bird 2.5
million years ago came to Berger when he was working at Gladysvale,
a hominid fossil site in the Transvaal hills. Suddenly, a black
eagle snatched a vervet monkey from a troop playing on the opposite
ridge. "I'd never dreamt an eagle could carry off something so big,
but when I saw the monkey dangling in those talons, something
clicked," says Berger.

Back in Johannesburg he looked up everything known about the
predatory habits of eagles. He and Clarke also spent months looking
at animal parts that accumulate in and around modern eagle nests,
and the characteristic damage to them, and comparing them with the
fossils collected from Taung.

They found that bones from modern eagle nests commonly show
depression fractures in the top and sides of the skulls, and
V-shaped cuts made by the beak. The base of the skull has usually
been torn away by the bird as it tries to get at the meat of the
brain. "All of these features are found repeatedly in the fossil
bones of Taung," says Berger. He believes the child's skull may have
tumbled from a nest in an overhanging tree and rolled into the cave
where it was found. "Nothing violated our theory," Berger says.

Other experts are divided over Berger's suggestion. "They've shown
that it's possible that eagles contributed to the collection of
baboon fossils at Taung, that's all," says Jeff McKee, who has
directed excavations at Taung for the past seven years. The baboon
skulls Berger and Clarke use to support their theory were not found
in the same spot as the Taung Child, he says, and many are believed
to be "at least 100 000 years" younger. Moreover, the top of the
child's skull is missing and the "indistinct" marks on the brain
cast could just as easily have been made by a tooth or a blow as by
a beak. McKee believes the child drowned and was washed into the
cave.

But there is encouragement from Bob Brain, whose own work on the
agents responsible for bone collections at South Africa's hominid
fossil sites is widely acclaimed. "This is a nice bit of work," he
says. "Berger and Clarke have given a plausible explanation for the
unusual assemblage of bones at Taung."

Who are we?
http://www.newscientist.com/article.ns?id=mg17623665.300&print=true

* 26 October 2002
* Bernard Wood

THERE is a popular image of human evolution that you'll find all
over the place, from the backs of cereal packets to advertisements
for expensive scientific equipment. On the left of the picture
there's an ape - stocky, jutting jaw, hunched in the knuckle-walking
position. On the right, a man - graceful, high forehead, striding
purposefully into the future. Between the two is a succession of
figures that become ever more like humans, as the shoulders start to
pull back, the torso slims down, the arms retract,the legs extend,
the cranium expands and the chin recedes. Our progress from ape to
human looks so smooth, so tidy. It's such a beguiling image that
even the experts are loath to let it go. But it is an illusion.

Cut to another picture of human evolution. This July, a cracked and
twisted face appeared on the front pages of most of the world's
major newspapers. The skull, unearthed in the Djurab Desert in Chad,
central Africa, is dated at between 6 and 7 million years old. At
the time it was hailed as our oldest ancestor. In recent weeks, that
claim has been bitterly disputed. Academic reputations may be at
stake, but behind all the ballyhoo, the true significance of this
find is emerging. It is forcing us to rethink the idea of human
evolution as a smooth progression without blind alleys or dead ends.
It can't possibly be so tidy, as within this framework the Chad
fossil makes no sense: this truly ancient specimen has the brain
case of a chimp together with a face that looks uncannily like our
ancestors living less than a million years ago.

My own research on fossils from East Africa convinced me long ago
that our evolutionary history is much more complex than we'd like to
think. Other palaeoanthropologists see a single line of descent that
you can follow like the trunk of a tree from its apex back down to
the roots, but I have long argued that our ancestry is more like a
bush with multiple tangled stems. Try following our own lineage back
to its origins and you soon get lost in the thicket. The Chad fossil
is most likely among the tangled stems at the base of the bush. But
is it our oldest known ancestor - the "missing link" between humans
and chimps? Indeed, is it one of us at all? If the new find has
taught us anything it is that, paradoxically, the more we discover
about our origins, the less we know.

One of the many things molecular biology has done is confirm that
humans are merely a rather peculiar African ape. Geneticists
estimate that our common ancestor lived between 4 and 10 million
years ago, based on the rate at which genetic mutations occur and
the measurement that we differ from chimps by 1 to 2 per cent of our
DNA. With the new finds from Chad - and other 6-million-year-old
remains discovered at a Kenyan Rift Valley site called Lukeino (see
New Scientist, 16 December 2000, p 5) - it looks increasingly likely
that the split happened earlier rather than later. So some time
between say 7 and 10 million years ago genetic variation within the
population of our common ancestor polarised into two lineages, or
"clades": one that includes us, and the other containing chimps and
bonobos.

Of course, we cannot look at the genes of our earliest ancestors.
Instead, we use fossil anatomy as a proxy for the genome, and treat
morphological similarities as if they were genetic ones. A competent
anatomist will be able to tell the difference between most
components of the modern human and chimp skeleton, but we
palaeoanthropologists face a much tougher and more subtle task. We
must trace these skeletal differences back in time, and work out
what they looked like when the chimp and human lineages diverged.
This is made more difficult because we have little idea of when the
structures and behaviours peculiar to chimps arose. Although chimps
have had their own independent evolutionary history going back as
far as ours, we have absolutely no fossil record of that evolution.

Nevertheless, the tidy interpretation of the human fossil record
suggests that the "gap" between modern humans and our common
ancestor with chimps has been filled. In this model you can trace
the origins of our own genus, Homo, back in time through Homo
erectus to Homo habilis and then to Australopithecus afarensis. The
gap to the common ancestor is bridged by Australopithecus anamensis
and finally Ardipithecus ramidus. Just one blip spoils the
conventional ladder-like succession: the "robust" australopiths, or
Paranthropus, who are generally interpreted as an extinct side
branch of human evolution. And the place of one other fossil
species, Australopithecus africanus from southern Africa, is
uncertain.

The tidy model also purports to give clues about the detailed
differences between the ancestral humans (hominins) and ancestral
chimps (panins) close to the time when they split. For example,
studies of teeth from Ar. ramidus suggest that one of the earliest
changes was in the size, shape and wear of the canines. Another
assumption is that early panins were adapted for life in the trees,
holding their torsos horizontally as they walked on all fours,
whereas the original hominin was probably a "facultative" biped, who
retained some tree-climbing abilities but was partially adapted for
walking on two legs. A. afarensis is a facultative biped, A.
anamensis is likely to be one also, but we don't yet know enough
about the skeleton of Ar. ramidus to tell how it moved. The
creatures down near the base of the human tree might also have had a
slightly larger brain than ancestral chimps.

Not long ago most researchers were quite sure that these so-called
"golden characters" would help us sort out the hominins from panins.
But the fuller the human fossil record becomes, the shakier is the
assumption that human characteristics such as manual dexterity,
bipedalism and large brains are so special that they evolved only
once. If this was the case, then the branching pattern, or
cladogram, showing the relationship between fossil specimens should
be clear and unambiguous. What's more, any piece of anatomy, or
"character", we use to reconstruct a cladogram should show the same
branching pattern as any other. But the reality is very different:
character cladograms conflict. Clearly, species with shared
morphology do not always inherit it from a common ancestor. The
technical term for this is homoplasy.

These days, most palaeoanthropologists agree that homoplasy occurs
in the later stages of hominin evolution - and also in the evolution
of extinct apes - so why not at the beginning of human evolution? In
addition, there is no reason why rudimentary upright walking and the
ability to make crude tools could not have evolved in a creature
that was genetically closer to a chimp than to a modern human. This
scenario becomes even more complicated if we entertain the
possibility that around 6 or 7 million years ago there may have been
apes that were neither ancestral chimps nor ancestral humans.
Personally, I think that this was most likely the case. If so, the
haystack gets larger, and the odds of finding and correctly
identifying the ancestral human needle become even longer.

This is the context in which the Chad discoveries should be set. The
fossil remains of Sahelanthropus tchadensis - the ape's correct
scientific name - which were unearthed by Michel Brunet from the
University of Poitiers and his colleagues, include a lower jaw and
teeth as well as the cranium containing the face. The jaw is thicker
than a chimp's, and the canines show the first signs of moving away
from an ape-like design - evidence consistent with its being an ape
at, or near, the base of the human clade. However, what most
definitely clashes with its 6 or 7-million-year-old date is the
beetle-browed upper face. We are used to seeing brow ridges on the
fossils of much later Homo species, none of which is older than 2
million years. And prominent brow ridges like the Chad ape's tend to
come much later.

If we use anatomy as a proxy for genetic relatedness, then the Chad
face connects it with hominins dated at less than a million years
old. That clearly can't be right. Although the Chad fossils were not
dated by isotope methods - there are no nearby volcanoes to provide
the necessary ash for carbon dating - fossil animals found at the
site match others from East Africa that date to between 6 and7
million years old. There is no way this ape is anywhere near as
recent as the Homo specimens it resembles. More ridiculous still,
under the terms of the tidy model where everything evolves just
once, the Chad specimen's ancient date and modern-looking brow ridge
means that any later fossil hominins with more primitive faces can't
possibly be our ancestors. That includes the famous "Lucy" skeleton
and even species we include in our own genus.

As a supporter of the untidy model of human evolution, I interpret
the Chad face very differently. The face of a skull is one of the
skeleton parts most likely to be affected by homoplasy. Despite
their physical similarities, the faces of the Chad ape and those of
later hominins were not necessarily inherited from a common
ancestor. Instead, they may simply have been shaped by similar
social or dietary demands. If so, then the Chad remains don't fit
neatly into a smooth progression of human evolution. But my
interpretation is surely less radical than throwing out 4 to 5
million years' worth of the hominin fossil record.

So, here is evidence for homoplasy right down at the base of the
human evolutionary tree. The Chad find strengthens my conviction
that our evolutionary history is far more complicated that many
experts are willing to admit. Accepting this is liberating. It
allows us to look afresh at the human fossil record and reclassify
some of the oddball specimens that most experts have previously
attempted to shoehorn into the tidy family tree. The resulting bush
may not appeal to our innate wish to impose order on the world, but
it is a more faithful representation of the evidence.

And the implications of the Chad finds stretch even further. I
believe these fossils also suggest that the earliest direct
ancestors of modern humans and chimps were just two components of a
diverse great ape fauna. This evolutionary bonanza, known as an
"adaptive radiation", was most probably a response to the global
cooling that was causing the contraction of African tropical forests
and the expansion of woodland environments around 8 million years
ago. Here, the location of the Chad fossil remains is significant.

Today, the site at Toros-Menalla in the Djurab Desert is little more
than sand as far as the eye can see, but 6 or 7 million years ago it
was forested, game was abundant and fish were plentiful in nearby
lakes. This also reminds us that when the first human ancestors were
beginning to appear, apes and ape-friendly environments were almost
certainly much more widespread than they are today. More tellingly
still, the Djurab Desert is over 1500 kilometres west of the East
African Rift Valley, long touted as the home of the original
hominins. Some experts have already questioned the conventional
wisdom that hominin evolution was somehow triggered by the
appearance of savannah grasslands in and around the Rift Valley. The
new finds confirm that this scenario must be thrown out.

So where does the Chad ape fit into this bigger, more complex
picture? It may well be a creature very close to the base of the
human bush, but it is impossible to tell whether it is a direct
ancestor of modern humans. Indeed, if we accept that we evolved at a
time when many new species of ape were emerging under the pressures
of environmental change, then identifying the fragmentary remains of
one of these apes as the hominin ancestor is likely to be a tall
order. Facultative bipedalism, increased dexterity, and even a
bigger brain, might have occurred in more than one member of an
adaptive radiation. In fact, we should expect to see novel mixtures
of familiar adaptations, and even novel adaptations, in a 7 to
10-million-year-old radiation of African apes.

We may never get a clear picture of the thicket of stems at the base
of our evolutionary bush. Certainly, the search for the "missing
link" is doomed to failure. But we can increase our understanding of
human evolution by recovering new evidence from known sites, and
from new sites in hitherto unexplored regions in central and West
Africa. We must also search for the remains of extinct panin, which
will provide a unique perspective on our own evolution.

Meet our new human relatives
http://www.newscientist.com/article.ns?id=mg18424711.000&print=true

* 30 October 2004
* Will Knight
* Rachel Nowak

SOME 13,000 years ago, on a tropical island at the heart of the
Indonesian archipelago, an extraordinary group of dwarf-sized people
lived alongside dwarf elephants and giant lizards. They belonged to
a species whose existence has been revealed to the world for the
first time this week. It is a species of human utterly new to
science.

In two papers in Nature, a team of researchers from Australia and
Indonesia detail the discovery of Homo floresiensis. So far the
skull and some bones of one female, tentatively called LB1 or Ebu,
and fragments from up to six other specimens of this extraordinary
relative of ours, have been unearthed from the Liang Bua limestone
caves 25 kilometres north of Ruteng on the western edge of the
island of Flores in central Indonesia.

Their discovery is arguably the most remarkable find in
palaeoanthropology for 50 years, and promises to transform the
conventional picture of human evolution. Instead of following a
simple evolutionary path culminating in modern Homo sapiens, the
existence of H. floresiensis suggests that early humans may have
evolved into many more varied forms than previously thought. And
these novel types of human survived until very recently,
out-surviving even our closest known relatives, the Neanderthals.
The new specimens also show that humans with tiny brains could
evolve without losing behavioural sophistication and intelligence.

"It is literally jaw-dropping," says Bernard Wood, an anthropologist
at George Washington University in Washington DC. "It raises the
whole issue of what it is to be human, or a member of the genus
Homo," adds Chris Stringer of the Natural History Museum in London.
"It shows how little we know about human evolution."

H. floresiensis is thought to be descended from ancestors that
became marooned on Flores some time during the past few hundred
thousand years. The resulting island people evolved to grow no more
than a metre tall with brains the size of a newborn modern human
(see "Anatomy of Homo floresiensis"). Their small stature and brain
size appear to be adaptations to isolated island conditions, where a
low-calorie diet and the lack of large predators made small bodies
advantageous.

The authenticity of the remains has been confirmed by
three-dimensional X-ray images, which reveal the internal structure
of the skull of LB1, something that would be almost impossible to
fake. Accelerator mass spectrometry dating also suggests that LB1's
remains are 18,000 years old. However, New Scientist has learned
that subsequent work has established that other H. floresiensis bone
fragments found at the site could be as young as 13,000 years old.
The oldest remains are 74,000 to 95,000 years old. That means H.
floresiensis survived well beyond the last Neanderthals, which are
thought to have disappeared from Europe and western Asia around
28,000 years ago. "The most remarkable thing is that there was a
time not so long ago when two very different human species walked
the planet," says Peter Brown of the University of New England in
New South Wales, Australia, who led the team that made the
discovery.

Strangely, however, the remains from Liang Bua reveal both modern
and ancient morphological traits. Femur and pelvis bones suggest
that the species stood upright but walked in a manner resembling the
earliest human ancestors that walked on two legs in Africa 4.5
million years ago. And H. floresiensis is the smallest species of
Homo yet known, with the smallest brain relative to its body. Its
cranium is even smaller than that of the earliest upright hominids,
with a volume of just 380 cubic centimetres, a fraction of the brain
volume of H. sapiens, which can reach 1650 cc.

In the overall shape of its skull and its teeth, the creature most
closely resembles Homo erectus, which lived until 200,000 years ago
and from which H. sapiens and Neanderthals are thought to descend.
This means it is also likely to have directly descended from H.
erectus.

Despite its small brain, evidence from Liang Bua suggests that H.
floresiensis may have had relatively sophisticated patterns of
behaviour. For example, a handful of stone tools from the same
period were found in the caves. There is no evidence that they were
inhabited by H. sapiens at the time, and Michael Morwood of the
University of New England, who co-directed the archaeological
excavation, says that H. floresiensis must have made the tools.

This would reveal remarkable intelligence, given the creature's
small cranium. "The internal structure of the brain - the neural
pathways - must have been more human-like than ape-like to be able
to make these types of tools," Brown says.

The bones and teeth of several juvenile dwarf stegodons, an ancestor
of the modern elephant, were also recovered from Liang Bua along
with the remains of fish, and other mammals including bats, rodents.
Some of these bones show signs of charring. This suggests H.
floresiensis may have hunted such animals before roasting them on
open fires.

The island on which these tiny humans lived lies just beyond the
eastern tip of Java, between the islands of Sumbawa and Timor. It is
divided by mountain chains and volcanoes and is inhabited by several
ethnic groups, each with a unique language and traditions.

As there is no evidence the island was ever linked by land to other
parts of south-east Asia, the ancestors of H. floresiensis might
have used boats or rafts to reach it. But the fact that this
population evidently became isolated suggests that they may have
relied on hitherto unsuspected land links that later disappeared.

H. sapiens is thought to have colonised Flores between 55,000 and
35,000 years ago. So H. floresiensis may have coexisted with modern
humans for tens of thousands of years. How the two populations
interacted remains a mystery. H. sapiens might have outcompeted H.
floresiensis for food and other resources, and this could have
played a part in the demise of the smaller species. But it is just
as likely that H. floresiensis was killed off by a volcanic eruption
on the island that occurred around 12,000 years ago.

Ongoing excavation at Liang Bua could reveal much more about H.
floresiensis. Further specimens might shed light on the species'
sexual dimorphism and the age at which individuals reached maturity,
for example. Further examination of its hand bones could also reveal
how dextrous it was.

But the discovery has already set the anthropological world in a
spin. Morwood says even stranger prehistoric human forms may have
inhabited the islands around Flores. "You are going to find many
more weird Homo species running around south-east Asia. Most will be
small and highly endemic. Some will be really weird," he says. "The
clear implication is that, given genetic isolation, genus Homo is
much more morphologically flexible."

Wood agrees. "It shows that the good Lord has a lot more tricks up
his sleeve," he says. "We haven't seen the best of them yet."

Instant Expert: Human Evolution
http://www.newscientist.com/article.ns?id=dn9990&print=true

Evolution - Learn more about the struggle to survive in our
comprehensive special report.

The incredible story of our evolution from ape ancestors spans 6
million years or more, and features the acquirement of traits from
bipedal walking, large brains, hairlessness, tool-making, hunting
and harnessing fire, to the more recent development of language,
art, culture and civilisation.

Darwin's The Origin of Species, published in 1859, suggested that
humans were descended from African apes. However, no fossils of our
ancestors were discovered in Africa until 1924, when Raymond Dart
dug up the "Taung child" - a 3-million to 4 million-year-old
Australopithecine.

Over the last century, many spectacular discoveries have shed light
on the history of the human family. Somewhere between 12 and 19
different species of early humans are recognised, though
palaeoanthropologists bitterly dispute how they are related. Famous
fossils include the remarkably complete "Lucy", dug up in Ethiopia
in 1974, and the astonishing "hobbit" species, Homo floresiensis,
found on an Indonesian island in 2004.

Walking tall

Humans are really just a peculiar African ape - we share about 98%
of our DNA with chimpanzees, our closest living relatives. Genetics
and fossil evidence hint that we last shared a common ancestor 7 to
10 million years ago - even if we continued hybridising long after.

At around 6 million years ago, the first apes to walk on two legs
appear in the fossil records. Despite the fact that many of these
Australopithecines and other early humans were no bigger than chimps
and had similar-sized brains, the shift to bipedalism was highly
significant. Aside from our large brain, bipedalism is perhaps the
most important difference between humans and apes, as it freed our
hands to use tools.

Bipedalism may have evolved when drier conditions shrank dense
African forests. It must have allowed our ancestors to spot
predators from further away, reach hanging fruit from the ground,
and reduce exposure to sunlight. Evidence that Australopithecines
walked upright includes analysis of the shape of their bones and
fossilised footprints.

One famous member of the species Australopithecus afarensis is the
remarkably complete fossil found by palaeaoanthropologist Donald
Johanson in Hadar, Ethiopia in 1974. The 3.2-million-year-old fossil
was named Lucy, after the Beatles' song Lucy in the Sky with
Diamonds.

She stood around 1.1 metres (3.5 feet) tall and although she walked
on two legs, she probably had a less graceful gait than us, since
she walked with them bent.

Scientist's have modelled her gait using computers. Their
characteristic long arms and curved fingers suggest that at least
some Australopithecines were still good climbers.

Hundreds of other fossils of Australopithecus afarensis have now
also been discovered. Other related early human species include
Australopithecus africanus - such as the Taung child -
3.5-million-year-old Kenyanthropus platyops, 5.8-million to
4.4-million-year-old Ardipithecus, 5.8-million-year-old Orrorin
tugenensis and 6 million year old Sahelanthropus tchadensis.

Tooled up

Australopithecines are thought to be the ancestors of Homo, the
group to which our own species, Homo sapiens, belongs.

However, Australopithecines may also have given rise to another
branch of hominid evolution - the vegetarian Paranthropus species.
Around 2.7 million years ago, species such as Paranthropus bosei in
east Africa evolved to take advantage of the dry grasslands. This
included the development of enormous jaws and chewing muscles for
grinding up tough roots and tubers.

By 2.4 million years ago, Homo habilis had appeared - the first
recognisably human-like hominid to appear in the fossil record which
lived alongside P. bosei. Their bodies were around two-thirds the
size of ours, but their brains were significantly larger than
Australopithecines with a volume of about 600 cubic centimetres.

H. habilis had much smaller teeth and jaws than Paranthropus and was
probably the first human to eat large quantities of meat. This meaty
diet, acquired through scavenging, may have provided energy required
to kick-start an increasing brain size. A mutation that weakened jaw
muscles and gave our brains more space to grow may also lie behind
the big brains we have today.

H. habilis - which means "handy man" - was also the first early
human to habitually create tools and use them to break bones and
extract marrow. This tool-making tradition, known as Oldowan, lasted
virtually unchanged for a million years. Oldowan tools were made by
breaking an angular rock with a "hammerstone" to give simple,
sharp-edged stone flakes for chopping and slicing.

Despite their own increases in brain size, the Paranthropus group of
species had become extinct by 1.2 million years ago. Some experts
speculate that it was learning to work as a team against predators
that gave Homo the edge.

Modern lookers

At around 1.65 million years ago, another early human, Homo
ergaster, started to create tools in a slightly different fashion.
This so-called Acheulean tradition was the tool-making technology
used for nearly the entire Stone Age, and practiced until 100,000
years ago. Acheulean tools, such as hand axes and cleavers, were
larger and more sophisticated than their predecessors. They may have
been status symbols as well as tools.

Homo ergaster first appeared in Africa around 2 million years ago,
and in many ways resembled us. Though they had brow ridges, they had
lost the stoop and long arms of their ancestors. They may have been
even more slender than us and were probably well-adapted to running
long distances. Some experts believe that they were the first to
sport largely hairless bodies, and to sweat, though another theory
puts our hairlessness down to an aquatic phase.

One famous example of a more modern looking early human is the
Turkana boy, a teenager when he died, 1.6 million years ago in
Kenya. The shape of this fossil showed that the human pelvis had
reached today's narrow proportions. Combined with the growing size
of the human head and brain, this had far-reaching implications:
human women now need help for a successful birth; and human babies
are born earlier, and need a longer period of childhood care, than
those of apes.

Meat-eating, however, may have allowed us to become early weaners.

H.ergaster may have been the first early human to leave Africa.
Bones dated to around 1.75 million years ago have been found in
Dmanisi in Georgia.

Shortly afterwards, Homo erectus appeared - the first early human
whose fossils have been seen in large numbers outside of Africa. The
first specimen discovered, a single cranium, was unearthed in
Indonesia in 1891. H.erectus was highly successful, spreading to
much of Asia between 1.8 and 1.5 million years ago, and surviving as
recently as 27,000 years ago.

This species, with a brain volume of around 1000 cm^3 would have
interacted with modern humans. They may have been the first people
to take to the seas and habitually hunt prey such as mammoths and
wild horses, although there is some debate about this. They may also
have harnessed the use of fire and built the first shelters.

In 2004, the remains of a tiny and mysterious human species, that
may have lived as recently as 13,000 years ago, was discovered on an
Indonesian island. More bones of the "hobbit", or Homo floresiensis,
were uncovered in 2005. Some studies suggest it had an advanced
brain and was unequivocally a separate species - but others argue
that these people were modern humans suffering from a genetic
disorder.

First Europeans

Early human fossil evidence from Spain, dating to around 780,000
years ago, points to the first known Europeans. Stone tools have
also been found in England from around 700,000 years ago, attributed
to Homo antecessor or Homo heidelbergensis.

More recently, 325,000-year-old H. heidelbergensis tracks were
discovered preserved on an Italian volcano. Some of the biggest
collections of hominid remains ever found are from Boxgrove in
England and Atapuerca in Spain. Experts believe that these humans
may have had ears equipped to detect nuances of human speech,
whether or not they had simple language.

Some palaeoanthropologists believe that H. heidelbergensis evolved
into our own species in Africa, whilst in Europe, the Neanderthals
emerged as a separate species.

The Neanderthals were found across Europe, between 200,000 and
28,000 years ago. Though they still possessed pronounced brow ridges
and were more thick-set, these people largely resembled us. They
were as nimble-fingered, and matured at a similar age to us. Their
brains were even slightly larger. It is not known if the
Neanderthals had developed simple language. But they did possess
some aspects of our culture, such as ritual burying of the dead;
creating art; using tools to attack each other; and complex hunting
methods - as evidenced by a remarkable butchery site in the UK.

Experts disagree about whether the Neanderthals hybridised with
humans or not, or if our arrival killed them. Plunging temperatures,
free trade and poor memory may all have contributed towards their
extinction.

Out of Africa

There are several competing theories about how all these early
humans are related to us today.

Most widely accepted is the "Out of Africa" hypothesis. This holds
that ancient humans evolved exclusively in Africa, then spread
across the world in two migration waves. The migration of H. erectus
across Eurasia made up the first wave. Later, our own species
evolved in Africa and fanned out in a second wave 200,000 years ago.
These new people totally replaced H. erectus in Asia and the
Neanderthals in Europe.

Advocates of the multiregional hypothesis instead believe that early
humans started to leave Africa around 2 million years ago, and were
never totally replaced by recent migrants. They believe these
far-flung hominids exchanged genes and interbred, slowly evolving
into modern humans - in many places, simultaneously. Through gene
flow, modern characteristics such as large brains gradually spread,
it is suggested. Some fossils seem to support the multiregional
hypothesis. H. erectus skulls in Asia, for example, have similarly
flat cheek and nasal regions as people there today do.

Most - but not all - genetic evidence appears to back the Out of
Africa hypothesis. There is surprisingly little variation in the
mitochondrial DNA (mDNA) of different people today, which suggest
that humans evolved recently from a small ancestral population. In
addition, the variation of mDNA in Africans is greater than
elsewhere, suggesting that people have been evolving there for
longer.

We may all be descended from a single African woman - dubbed
Mitochondrial Eve - within the last 200,000 years. Male Y-chromosome
DNA hints at a single male progenitor, too. Fewer than 50 people
could have given rise to the entire population of Europe, experts
believe.

Cultural revolution

The earliest anatomically modern humans are though to have arrived
around 200,000 years ago. These fossils show a rounded braincase and
flatter face. Their brains had reached modern proportions of about
1350 cm^3. Two skulls found in Ethiopia make up the oldest modern
human remains known, at 195,000 years old.

Modern humans had made it to Asia by 90,000 years ago, Australia by
60,000 years ago, Europe and the Arctic by 40,000 years ago, and the
Americas by 12,000 years ago.

Throughout history, tool use appears to have progressed slowly -
once innovations were made, they lasted millions of years barely
altering. But around 50,000 years ago something changed, and culture
started to develop at a much more rapid rate.

Modern humans habitually began innovating new tools types, burying
their dead, creating jewellery, developing sophisticated hunting
techniques such as pitfall traps, using animal skins for clothing,
decorating their bodies, and creating art and cave paintings.
Although some of these traits appeared earlier, they seem to have
only have been used sporadically until this time.

These changes may have been linked to increasing brain size or the
way we thought - or could also be due to free trade, and the
evolution of language and communication. The dawn of human
civilisation has been dated to around 30,000 years ago. The earliest
agriculture and domestication of species is known only as recently
as 10,000 years ago. The first human cities appeared in Mesopotamia
around 4,000 years ago.

Are we still evolving today? If so, how will we evolve in the
future? Some argue that humans have evolved little in the last
50,000 years - but other studies suggests that thousands of genes
have changed since then.

We may even be on the verge of the next step of human evolution -
the human global "superorganism".

Timeline: Human Evolution
http://www.newscientist.com/article.ns?id=dn9989&print=true

* 12:15 04 September 2006
* John Pickrell

55 million years ago (MYA)
First primitive primates evolve

8 - 6 MYA
First gorillas evolve. Later, chimp and human lineages diverge

5.8 MYA
Orrorin tugenensis, oldest human ancestor thought to have walked on
two legs

5.5 MYA
Ardipithecus, early "proto-human" shares traits with chimps and
gorillas, and is forest-dwelling

4 MYA
Australopithecines appear. They have brains no larger than a
chimpanzee's with a volume around 400 500 cm^3 -, but walk upright
on two legs. First human ancestors to live on the savannah

3.2 MYA
Lucy, famous specimen of Australopithecus afarensis, lives near what
is now Hadar, Ethiopia

2.7 MYA
Paranthropus, lives in woods and grasslands, has massive jaws for
chewing on roots and vegetation. Becomes extinct 1.2 MYA

2.5 MYA
Homo habilis appears. Its face protrudes less than earlier hominids,
but still retains many ape features. Has a brain volume of around
600 cm^3

Hominids start to use stone tools regularly, created by splitting
pebbles this starts Oldowan tradition of toolmaking, which last a
million years

Some hominids develop meat-rich diets as scavengers, the extra
energy may have favoured the evolution of larger brains

2 MYA
Evidence of Homo ergaster, with a brain volume of up to 850 cm^3, in
Africa

1.8 1.5 MYA
Homo erectus is found in Asia. First true hunter-gatherer ancestor,
and also first to have migrated out of Africa in large numbers. It
attains a brain size of around 1000 cm^3

1.6 MYA
Possible first sporadic use of fire suggested by discoloured
sediments in Koobi Fora, Kenya. More convincing evidence of charred
wood and stone tools is found in Israel and dated to 780,000 years
ago

More complex Acheulean stone tools start to be produced and are the
dominant technology until 100,000 years ago

600,000 YA
Homo Heidelbergensis lives in Africa and Europe. Similar brain
capacity to modern humans

500,000 YA
Earliest evidence of purpose-built shelters - wooden huts - are
known from sites near Chichibu, Japan

400,000 YA
Early humans begin to hunt with spears

325,000 YA
Oldest surviving early human footprints are left by three people who
scrambled down the slopes of a volcano in Italy

280,000 YA
First complex stone blades and grinding stones

230,000 YA
Neanderthals appear and are found across Europe, from Britain in the
west to Iran in the east, until they become extinct with the advent
of modern humans 28,000 years ago

195,000 YA
Our own species Homo sapiens appears on the scene and shortly after
begins to migrate across Asia and Europe. Oldest modern human
remains are two skulls found in Ethiopia that date to this period.
Average human brain volume is 1350 cm^3

170,000 YA
Mitochondrial Eve, the direct ancestor to all living people today,
may have been living in Africa

150,000 YA
Humans possibly capable of speech. 100,000-year-old shell jewellery
suggests that that people develop complex speech and symbolism

140,000 YA
First evidence of long-distance trade

110,000 YA
Earliest beads made from ostrich eggshells and jewellery

50,000 YA
"Great leap forward": human culture starts to change much more
rapidly than before; people begin burying their dead ritually;
create clothes from animal hides; and develop complex hunting
techniques, such as pit-traps.

Colonisation of Australia by modern humans
33,000 YA

Oldest cave art. Later, Stone Age artisans create the spectacular
murals at Lascaux and Chauvet in France

Homo erectus dies out in Asia replaced by modern man

18,000 YA
Homo Floresiensis, "Hobbit" people, found on the Indonesian island
of Flores. They stand just over 1 metre tall, and have brains
similar in size to chimpanzees, yet have advanced stone tools

12,000 YA
Modern people reach the Americas

10,000 YA
Agriculture develops and spread. First villages. Possible
domestication of dogs

5,500 YA
Stone Age ends and Bronze Age begins. Humans begin to smelt and work
copper and tin, and use them in place of stone implements

5,000 YA
Earliest known writing

4,000 to 3,500 BC
The Sumerians of Mesopotamia develop the world's first civilisation

How culture made your modern mind
http://www.newscientist.com/article.ns?id=mg19826564.300&print=true

* 14 May 2008
* Andy Coghlan

IT IS one of the hottest questions of our time: how did our
cognitive abilities explode, leaving other animals for dust
intellectually?

Now a new explanation is emerging. Controversially, it challenges
the idea that biology alone is what drove the evolution of
intellectual skills. What if we acquired abilities such as the
capacity to invent, converse or work in unison as a result of a
continual process of cultural cross-fertilisation with the world we
inhabit, and through the way we interact with other people and
material things?

Not only does this idea help explain how our species blossomed
intellectually in the first place but it implies that our brains are
continually changing whenever we meet new cultural concepts, objects
and technologies, whether they are cellphones or new religions.

After Homo sapiens emerged about 200,000 years ago, it took around
140,000 years before any sign of modern civilisation emerged. So
what happened that finally turned Stone Age boneheads into
whizz-kids capable of creating stone tools, painting cave art and
arranging burial rites for the dead? Various researchers explored
this question at a historic meeting in September 2007 in Cambridge,
UK, entitled "The Sapient Mind". Their discussions and conclusions
were published last month in a collection of scientific papers in
Philosophical Transactions of the Royal Society B.

A number of the researchers who contributed papers think that up to
a certain point in history, biological factors alone controlled our
brain's development. Then around 60,000 to 70,000 years ago, the
biology and structure of our brains stopped changing and other
factors began to take over as the main driver of human development.

For this to happen, however, the biological groundwork needed to be
in place, they say. One of those biological foundations may have
been the gradual expansion of working memory, which eventually
enabled us to retain memories from the past, recognise objects in
the present and plan ahead and conceive of a future (see "We're
streets ahead").

The second was the emergence of a "theory of mind", which is the
realisation that other creatures are intelligent and capable of
independent thought and intention. It derives from the activity of
"mirror" systems in the brain which enable an observer to feel the
experiences of others, and to divine their intentions and motives.

Günther Knoblich of the University of Birmingham, UK, argues that a
theory of mind and the capacity to separate the intentions of others
from our own was a critical neurological breakthrough. It enabled
humans to cooperate on tasks such as using the combined strength of
several people to move a heavy object or hunt together. Even though
these feats may have been accomplished without language and with the
help of nothing more than gestures, signals and facial cues, they go
way beyond simple mimicry of others, he says, which many animals can
do.

Yet perhaps the biggest opportunity opened up by a theory of mind
and an expanded working memory was the ability to learn, and to
systematically educate other people. Animals learn by random
observations of what other animals do. It is very seldom that they
recognise the value of an innovation by their peers and then copy it
themselves, such as shaking a tree to make fruit fall.

But thanks to theory of mind and the ability to divine the
intentions of others, humans were able to train their offspring.
During the process of teaching, both pupils and teachers are well
aware of what's happening and know they must pay special attention
beyond random observation. What's more, as working memory expanded,
learning would have become more efficient.

This may have allowed us to steal a march on other species and our
close relatives. "As far as I know, chimps don't teach each other,"
says Chris Frith of University College London. "So a chimp baby can
learn by watching its mother, but does not explicitly get
instructed. Nor is there teaching to take account of the lack of
knowledge of the infant," he says.

Once teaching became possible for humans, differences between
cultural groups would have begun to emerge, because different rules
and traditions would have slowly been established in different
communities, and passed down to consolidate social unity. This means
that specific cognitive skills would have developed and would have
dictated what elements of behaviour and achievement were seen as
important by that culture.

As a modern example, take the case of Dauya, a
magician-cum-astronomer from a tribe on Boyowa Island in Papua New
Guinea. Interviewed in 1976 by Edwin Hutchins of the University of
California, San Diego, who contributed one of the papers, Dauya had
been taught the task of notifying his fellow islanders when the
Pleiades constellation becomes visible at dawn from a particular
beach on Boyowa Island. When it does, that's the time for islanders
to plant their crops, because the tribe has learned after many years
of observation that it coincides with the start of the growing
season, even when the weather suggests that time may not be right.
Dauya's task and the fact that he has been taught it is a
considerable intellectual achievement, considering the tribe is
pre-literate. Yet this skill is unique to the cultural context of
communities on Boyowa Island, and has only developed because of it.

Our interactions with material objects and surroundings also
influenced the capabilities of the brain since a theory of mind and
working memory became established, according to Chris Gosden of the
University of Oxford.

Perhaps the best modern-day evidence that objects and surroundings
influence brain structure and function is seen in London taxi
drivers, who develop enlarged hippocampuses to accommodate their
abnormally large mental street map of London. "It's the condition of
actually doing things that cumulatively shapes our thoughts and
shapes our brains," says Gosden.

Dwight Read, an anthropologist at the University of California, Los
Angeles, and colleagues argue a pivotal moment in human development
came about 10,000 years ago, when our relationship with objects and
material things changed significantly. Around this time, groups of
hunter-gatherers began to replace their hunting spears with
domesticated plants and animals, and to settle in a particular
location. This meant they recognised the concept of "inside" and
"outside" a living space and could create individually worked fields
and enclosures for livestock and crops.

"Consequently, problem-solving rather than moving to a new location
became the key to survival," he says. Once that had happened, the
ability to teach systematically, to work together to solve problems,
and the brain's capacity to adapt to cultural change truly came into
its own, and any hold biology still had was released. After that, it
seems, our ingenuity just exploded.

The Human Brain - With one hundred billion nerve cells, the
complexity is mind-boggling. Learn more in our cutting edge special
report.

Human Evolution - Follow the incredible story in our comprehensive
special report.

The right tools for language

Did the explosion in tool-making coincide with the emergence of
language?

Dietrich Stout and colleagues at University College London took
brain scans as three archaeologists skilled in making Stone Age
tools practised their craft. They found that parts of the brain that
became active coincided with areas vital for language. "Putting
together a complicated sentence and making a tool are similar
challenges, and so the underlying process is similar," says Stout.
"It's calling on overlapping parts of the brain."

Likewise, Scott Frey of the University of Oregon found after
studying patients with brain injuries, and scanning healthy
individuals, that areas of the left hemisphere are crucial for
planning the use of familiar tools. These areas also appear to
underlie our ability to perform symbolic gestures, which some
suggest may pre-date the evolution of speech. "The specific areas
showing increased activity in healthy patients are those most likely
to be damaged in patients with apraxia, a deficit in performance of
manual skills," says Frey.

We're streets ahead in the memory game

Compare our genes with a chimp's, and there's not much difference.
Yet it's a different story when you look at "working memory".

Located in the prefrontal and parietal cortices, the "thinking"
parts of the human brain, working memory enables us to link the past
and present, and allows us to conceive of a future. No other species
has developed this capacity so completely as humans, and early on it
may well have allowed us to steal a march on our most recent
ancestors.

Dwight Read, an anthropologist at the University of California, Los
Angeles, and colleagues reckon our working memory underwent a
gradual expansion till it reached a critical point about 60,000
years ago, when cognitive abilities such as systematic learning took
off.

He and co-author Sander van der Leeuw of Arizona State University in
Temple, Arizona, base their assertions on comparisons of working
memory in chimpanzees and modern-day humans. They estimated working
memory capacity in chimpanzees from measurements of their
performance in tasks such as cracking nuts with stones. For modern
humans, they estimated memory capacity from published accounts of
how babies' capabilities expand until they reach puberty. On a
nominal scale of 1 to 7, humans reach a memory capacity of about 7
by the age of 12, whereas chimps seldom get beyond 2 or 3 on the
scale.

The upshot is that in terms of tool use and manufacture, chimps
simply can't compete with the accomplishments of modern humans or,
by implication, our ancestors of 60,000 years ago, who had
comparable brains to ours biologically. They can't learn as
efficiently, for instance. So whereas our ancestors could have
easily learned to crack open nuts, a quarter of chimpanzees can't
learn to do this, however many times they see the task performed.

Related Articles

* Religion: a figment of human imagination?
* http://www.newscientist.com/article.ns?id=dn13782
* 28 April 2008
* Menopause sets humans apart from chimps
* http://www.newscientist.com/article.ns?id=mg19626354.700
* 22 December 2007
* Source of human empathy found in brain
* http://www.newscientist.com/article.ns?id=mg19626294.600
* 12 November 2007
* The big questions: what is consciousness?
* http://www.newscientist.com/article.ns?id=mg19225780.073
* 18 November 2006

Weblinks

* "Sapient mind" papers
* http://publishing.royalsociety.org/index.cfm?page=1423
* Dwight Read
* http://www.sscnet.ucla.edu/anthro/faculty/read/
* Dietrich Stout
* http://www.ucl.ac.uk/archaeology/staff/profiles/stout.htm
* Scott Frey
* http://www.ucl.ac.uk/archaeology/staff/profiles/stout.htm
* Fiona Coward
* http://www.ucl.ac.uk/archaeology/staff/profiles/stout.htm
* Scott Frey
* http://www.ucl.ac.uk/archaeology/staff/profiles/stout.htm

Instant Expert: Human Evolution
http://www.newscientist.com/article.ns?id=dn9990&print=true

* 12:16 04 September 2006
* John Pickrell

The incredible story of our evolution from ape ancestors spans 6
million years or more, and features the acquirement of traits from
bipedal walking, large brains, hairlessness, tool-making, hunting
and harnessing fire, to the more recent development of language,
art, culture and civilisation.

Darwin's The Origin of Species, published in 1859, suggested that
humans were descended from African apes. However, no fossils of our
ancestors were discovered in Africa until 1924, when Raymond Dart
dug up the "Taung child" - a 3-million to 4 million-year-old
Australopithecine.

Over the last century, many spectacular discoveries have shed light
on the history of the human family. Somewhere between 12 and 19
different species of early humans are recognised, though
palaeoanthropologists bitterly dispute how they are related. Famous
fossils include the remarkably complete "Lucy", dug up in Ethiopia
in 1974, and the astonishing "hobbit" species, Homo floresiensis,
found on an Indonesian island in 2004.

Walking tall

Humans are really just a peculiar African ape - we share about 98%
of our DNA with chimpanzees, our closest living relatives. Genetics
and fossil evidence hint that we last shared a common ancestor 7 to
10 million years ago - even if we continued hybridising long after.

At around 6 million years ago, the first apes to walk on two legs
appear in the fossil records. Despite the fact that many of these
Australopithecines and other early humans were no bigger than chimps
and had similar-sized brains, the shift to bipedalism was highly
significant. Aside from our large brain, bipedalism is perhaps the
most important difference between humans and apes, as it freed our
hands to use tools.

Bipedalism may have evolved when drier conditions shrank dense
African forests. It must have allowed our ancestors to spot
predators from further away, reach hanging fruit from the ground,
and reduce exposure to sunlight. Evidence that Australopithecines
walked upright includes analysis of the shape of their bones and
fossilised footprints.

One famous member of the species Australopithecus afarensis is the
remarkably complete fossil found by palaeaoanthropologist Donald
Johanson in Hadar, Ethiopia in 1974. The 3.2-million-year-old fossil
was named Lucy, after the Beatles' song Lucy in the Sky with
Diamonds.

She stood around 1.1 metres (3.5 feet) tall and although she walked
on two legs, she probably had a less graceful gait than us, since
she walked with them bent.

Scientist's have modelled her gait using computers. Their
characteristic long arms and curved fingers suggest that at least
some Australopithecines were still good climbers.

Hundreds of other fossils of Australopithecus afarensis have now
also been discovered. Other related early human species include
Australopithecus africanus - such as the Taung child -
3.5-million-year-old Kenyanthropus platyops, 5.8-million to
4.4-million-year-old Ardipithecus, 5.8-million-year-old Orrorin
tugenensis and 6 million year old Sahelanthropus tchadensis.

Tooled up

Australopithecines are thought to be the ancestors of Homo, the
group to which our own species, Homo sapiens, belongs.

However, Australopithecines may also have given rise to another
branch of hominid evolution - the vegetarian Paranthropus species.
Around 2.7 million years ago, species such as Paranthropus bosei in
east Africa evolved to take advantage of the dry grasslands. This
included the development of enormous jaws and chewing muscles for
grinding up tough roots and tubers.

By 2.4 million years ago, Homo habilis had appeared - the first
recognisably human-like hominid to appear in the fossil record which
lived alongside P. bosei. Their bodies were around two-thirds the
size of ours, but their brains were significantly larger than
Australopithecines with a volume of about 600 cubic centimetres.

H. habilis had much smaller teeth and jaws than Paranthropus and was
probably the first human to eat large quantities of meat. This meaty
diet, acquired through scavenging, may have provided energy required
to kick-start an increasing brain size. A mutation that weakened jaw
muscles and gave our brains more space to grow may also lie behind
the big brains we have today.

H. habilis - which means "handy man" - was also the first early
human to habitually create tools and use them to break bones and
extract marrow. This tool-making tradition, known as Oldowan, lasted
virtually unchanged for a million years. Oldowan tools were made by
breaking an angular rock with a "hammerstone" to give simple,
sharp-edged stone flakes for chopping and slicing.

Despite their own increases in brain size, the Paranthropus group of
species had become extinct by 1.2 million years ago. Some experts
speculate that it was learning to work as a team against predators
that gave Homo the edge.

Modern lookers

At around 1.65 million years ago, another early human, Homo
ergaster, started to create tools in a slightly different fashion.
This so-called Acheulean tradition was the tool-making technology
used for nearly the entire Stone Age, and practiced until 100,000
years ago. Acheulean tools, such as hand axes and cleavers, were
larger and more sophisticated than their predecessors. They may have
been status symbols as well as tools.

Homo ergaster first appeared in Africa around 2 million years ago,
and in many ways resembled us. Though they had brow ridges, they had
lost the stoop and long arms of their ancestors. They may have been
even more slender than us and were probably well-adapted to running
long distances. Some experts believe that they were the first to
sport largely hairless bodies, and to sweat, though another theory
puts our hairlessness down to an aquatic phase.

One famous example of a more modern looking early human is the
Turkana boy, a teenager when he died, 1.6 million years ago in
Kenya. The shape of this fossil showed that the human pelvis had
reached today's narrow proportions. Combined with the growing size
of the human head and brain, this had far-reaching implications:
human women now need help for a successful birth; and human babies
are born earlier, and need a longer period of childhood care, than
those of apes.

Meat-eating, however, may have allowed us to become early weaners.

H.ergaster may have been the first early human to leave Africa.
Bones dated to around 1.75 million years ago have been found in
Dmanisi in Georgia.

Shortly afterwards, Homo erectus appeared - the first early human
whose fossils have been seen in large numbers outside of Africa. The
first specimen discovered, a single cranium, was unearthed in
Indonesia in 1891. H.erectus was highly successful, spreading to
much of Asia between 1.8 and 1.5 million years ago, and surviving as
recently as 27,000 years ago.

This species, with a brain volume of around 1000 cm^3 would have
interacted with modern humans. They may have been the first people
to take to the seas and habitually hunt prey such as mammoths and
wild horses, although there is some debate about this. They may also
have harnessed the use of fire and built the first shelters.

In 2004, the remains of a tiny and mysterious human species, that
may have lived as recently as 13,000 years ago, was discovered on an
Indonesian island. More bones of the "hobbit", or Homo floresiensis,
were uncovered in 2005. Some studies suggest it had an advanced
brain and was unequivocally a separate species - but others argue
that these people were modern humans suffering from a genetic
disorder.

First Europeans

Early human fossil evidence from Spain, dating to around 780,000
years ago, points to the first known Europeans. Stone tools have
also been found in England from around 700,000 years ago, attributed
to Homo antecessor or Homo heidelbergensis.

More recently, 325,000-year-old H. heidelbergensis tracks were
discovered preserved on an Italian volcano. Some of the biggest
collections of hominid remains ever found are from Boxgrove in
England and Atapuerca in Spain. Experts believe that these humans
may have had ears equipped to detect nuances of human speech,
whether or not they had simple language.

Some palaeoanthropologists believe that H. heidelbergensis evolved
into our own species in Africa, whilst in Europe, the Neanderthals
emerged as a separate species.

The Neanderthals were found across Europe, between 200,000 and
28,000 years ago. Though they still possessed pronounced brow ridges
and were more thick-set, these people largely resembled us. They
were as nimble-fingered, and matured at a similar age to us. Their
brains were even slightly larger. It is not known if the
Neanderthals had developed simple language. But they did possess
some aspects of our culture, such as ritual burying of the dead;
creating art; using tools to attack each other; and complex hunting
methods - as evidenced by a remarkable butchery site in the UK.

Experts disagree about whether the Neanderthals hybridised with
humans or not, or if our arrival killed them. Plunging temperatures,
free trade and poor memory may all have contributed towards their
extinction.

Out of Africa

There are several competing theories about how all these early
humans are related to us today.

Most widely accepted is the "Out of Africa" hypothesis. This holds
that ancient humans evolved exclusively in Africa, then spread
across the world in two migration waves. The migration of H. erectus
across Eurasia made up the first wave. Later, our own species
evolved in Africa and fanned out in a second wave 200,000 years ago.
These new people totally replaced H. erectus in Asia and the
Neanderthals in Europe.

Advocates of the multiregional hypothesis instead believe that early
humans started to leave Africa around 2 million years ago, and were
never totally replaced by recent migrants. They believe these
far-flung hominids exchanged genes and interbred, slowly evolving
into modern humans - in many places, simultaneously. Through gene
flow, modern characteristics such as large brains gradually spread,
it is suggested. Some fossils seem to support the multiregional
hypothesis. H. erectus skulls in Asia, for example, have similarly
flat cheek and nasal regions as people there today do.

Most - but not all - genetic evidence appears to back the Out of
Africa hypothesis. There is surprisingly little variation in the
mitochondrial DNA (mDNA) of different people today, which suggest
that humans evolved recently from a small ancestral population. In
addition, the variation of mDNA in Africans is greater than
elsewhere, suggesting that people have been evolving there for
longer.

We may all be descended from a single African woman - dubbed
Mitochondrial Eve - within the last 200,000 years. Male Y-chromosome
DNA hints at a single male progenitor, too. Fewer than 50 people
could have given rise to the entire population of Europe, experts
believe.

Cultural revolution

The earliest anatomically modern humans are though to have arrived
around 200,000 years ago. These fossils show a rounded braincase and
flatter face. Their brains had reached modern proportions of about
1350 cm^3. Two skulls found in Ethiopia make up the oldest modern
human remains known, at 195,000 years old.

Modern humans had made it to Asia by 90,000 years ago, Australia by
60,000 years ago, Europe and the Arctic by 40,000 years ago, and the
Americas by 12,000 years ago.

Throughout history, tool use appears to have progressed slowly -
once innovations were made, they lasted millions of years barely
altering. But around 50,000 years ago something changed, and culture
started to develop at a much more rapid rate.

Modern humans habitually began innovating new tools types, burying
their dead, creating jewellery, developing sophisticated hunting
techniques such as pitfall traps, using animal skins for clothing,
decorating their bodies, and creating art and cave paintings.
Although some of these traits appeared earlier, they seem to have
only have been used sporadically until this time.

These changes may have been linked to increasing brain size or the
way we thought - or could also be due to free trade, and the
evolution of language and communication. The dawn of human
civilisation has been dated to around 30,000 years ago. The earliest
agriculture and domestication of species is known only as recently
as 10,000 years ago. The first human cities appeared in Mesopotamia
around 4,000 years ago.

Are we still evolving today? If so, how will we evolve in the
future? Some argue that humans have evolved little in the last
50,000 years - but other studies suggests that thousands of genes
have changed since then.

We may even be on the verge of the next step of human evolution -
the human global "superorganism".

Out of Asia
http://www.newscientist.com/article.ns?id=mg18224485.300&print=true

* 22 May 2004
* Richard Hollingham

IT WAS in the dust of an industrial limestone quarry near Shanghai
in China that palaeontologist Chris Beard made the discovery of a
lifetime. It didn't look like much - just a few small teeth set in a
fragment of lower jaw - but it changed his view of human evolution
forever. By naming the fossilised remains Eosimias sinensis, or
"dawn monkey of China", he knew he was courting controversy. He got
it.

Beard, of the Carnegie Museum of Natural History in Pittsburgh,
Pennsylvania, had committed two scientific heresies. First, he was
implicitly claiming to have found the first simian, or higher
primate, and therefore the oldest known direct ancestor of humans.
Secondly, he was implying that our early ancestors came from Asia.

These claims could hardly be further from the orthodox view, which
is that the higher primates evolved in Africa about 35 million years
ago, diversified in Africa, and did not spread out into Asia until
10 million years later. In other words, the entire story of human
evolution was played out in Africa. But to Beard and his supporters,
the discovery of Eosimias suggested something different: the higher
primates evolved in Asia, diversified in Asia and only later spread
to Africa.

In appearance at least, Eosimias would seem to bear little relation
to a human. From jaw and other bone fragments, Beard has been able
to reconstruct its likely appearance and make some guesses about its
behaviour. "It would be small enough to hold in the palm of your
hand," he says. "It would have a fast metabolism, eating
high-calorie foods like insects and fruit and have nervous, almost
frenetic, behaviour." Like other primates Eosimias would have
forward-looking eyes and grasping limbs. Its closest living analogue
is probably the pygmy marmoset.

But although it might not look much like a modern higher primate,
particularly apes and humans, Beard believes Eosimias is a vital
link in the story of how humans came to be. "The evolution of higher
primates has immense scientific and philosophical implications for
human origins," he says. "There has been an intense focus on the
last little segment of human evolution, but imagine trying to
document the history of western civilisation if we knew nothing
about Plato, Aristotle or the rise and fall of the Roman empire."

Higher primates, also known as simians or anthropoids, include new
and old-world monkeys, apes and hominids. The rest of the primate
order, called lower primates or prosimians, comprise the lorises,
bushbabies, lemurs, tarsiers and two extinct groups (see Diagram).
There are around 240 living species of primate ranging from the
mouse lemur to the 160-kilogram mountain gorilla. All share
stereoscopic colour vision, grasping limbs and larger brains than
other mammals. What distinguishes higher primates from the
prosimians is a greater reliance on sight compared with the other
senses, flexibility of movement culminating in bipedalism and,
crucially, larger brains.

The higher primate suborder is diverse, ranging from squirrel
monkeys to baboons, chimpanzees to humans. But at some point in the
past we all shared a common ancestor. The general consensus is that
this ancestor split off from the Tarsiidae, a group of insect-eaters
that lives on in the form of the saucer-eyed tarsiers, about 30
million years ago.

Until recently there seemed little doubt that this split occurred in
Africa. Duri