No subject

distinctive call that female baboons always make after mating. He
recognizes the voice as that of Jackalberry, the current consort of
Cassius, a male who outranks Royal in the strict hierarchy of male
baboons. No hope of sex today.

But then, surprisingly, he hears Cassiuss signature greeting grunt
to his left. His puzzlement is plain on the video made of his
reaction. You can almost see the wheels turn slowly in his head:

Jackalberry here, but Cassius over there. Hmm, Jackalberry must be
hooking up with some one else. But that means Cassius has left her
unguarded. Say what this is my big chance!

The video shows him loping off in the direction of Jackalberrys
whoop. But all that he will find is the loudspeaker from which
researchers have played Jackalberrys recorded call.

The purpose of the experiment is not to ruin Royals day but to
understand what goes on in a baboons mind, in this case how
carefully the animals keep track of transient relationships.

Dorothy Cheney and Robert Seyfarth, a husband-and-wife team of
biologists at the University of Pennsylvania, have spent 14 years
observing the Moremi baboons. Through ingenious playback
experiments performed by themselves and colleagues, the researchers
say they have worked out many aspects of what baboons use their
minds for, along with their limitations.

Reading a baboons mind affords an excellent grasp of the dynamics
of baboon society. But more than that, it bears on the evolution of
the human mind and the nature of human existence. As Darwin jotted
down in a notebook of 1838, He who understands baboon would do more
towards metaphysics than Locke.

Dr. Cheney and Dr. Seyfarth are well known for a 1990 book on
vervet monkeys, How Monkeys See the World, in which they showed how
much about the animals mental processes could be deduced from
careful experiments.

When a baby vervets call is played to three females, for instance,
the mother looks to the source of the sound. The two others look to
the mother, evidence that vervets know whose baby is whose.

An experiment like this recording the sounds, waiting until the
animals are in the right place and performing numerous controls can
take months to complete, but the results are widely admired by
other biologists. Any work of Dorothy and Roberts is going to be as
good as you get in the field, said Robert M. Sapolsky, a Stanford
biologist and an author who has studied baboons in the wild for
many years.

There is no one else in the area of animal behavior who does such
incredibly interesting experiments in the field, said Marc Hauser,
a biologist at Harvard who was their first student.

Dr. Cheney and Dr. Seyfarth have summed up their new cycle of
research in a book titled, after Darwins comment, Baboon
Metaphysics. Their conclusion, based on many painstaking
experiments, is that baboons minds are specialized for social
interaction, for understanding the structure of their complex
society and for navigating their way within it.

The shaper of a baboons mind is natural selection. Those with the
best social skills leave the most offspring.

Monkey society is governed by the same two general rules that
governed the behavior of women in so many 19th-century novels, Dr.
Cheney and Dr. Seyfarth write. Stay loyal to your relatives (though
perhaps at a distance, if they are an impediment), but also try to
ingratiate yourself with the members of high-ranking families.

Baboon society revolves around mother-daughter lines of descent.
Eight or nine matrilines are in a troop, each with a rank order.
This hierarchy can remain stable for generations.

By contrast, the male hierarchy, which consists mostly of baboons
born in other troops, is always changing as males fight among
themselves and with new arrivals.

Rank among female baboons is hereditary, with a daughter assuming
her mothers rank.

News of that fact gave great satisfaction to a member of the
British royal family, Princess Michael of Kent. She visited Dr.
Cheney and Dr. Seyfarth in Botswana, remarking to them, they
report: I always knew that when people who arent like us claim that
hereditary rank is not part of human nature, they must be wrong.
Now youve given me evolutionary proof!

Baboons live with danger on every side. Many fall prey to lions,
leopards, pythons and the crocodiles that in the wet season stalk
the fords where baboons cross from one island to another. Baboon
watchers are subject to the same hazards. Dr. Cheney and Dr.
Seyfarth say their rules are not to work alone or to wade into
water deeper than knee high. They often find themselves sitting in
a tree with baboons waiting out a lion below. But going into New
York is more petrifying, they contend, than dodging Botswanas
predators.

The baboons will bark to warn of lions and leopards, but pay no
attention to some other species dangerous to humans like buffalo
and elephant. On two occasions, baboons have attacked animals, a
leopard and a honey badger, that threatened their human companions.
We havent lost any post-docs, Dr. Seyfarth said.

For female baboons, another constant worry besides predation is
infanticide. Their babies are put in peril at each of the frequent
upheavals in the male hierarchy. The reason is that new alpha males
enjoy brief reigns, seven to eight months on average, and find at
first that the droits de seigneur they had anticipated are
distinctly unpromising. Most of the females are not sexually
receptive because they are pregnant or nurturing unweaned children.

An unpleasant fact of baboon life is that the alpha male can make
mothers re-enter their reproductive cycles, and boost his prospects
of fatherhood, by killing their infants. The mothers can secure
some protection for their babies by forming close bonds with other
females and with male friends, particularly those who were alpha
when their children were conceived and who may be the father.
Still, more than half of all deaths among baby baboons are from
infanticide.

So important are these social skills that it is females with the
best social networks, not those most senior in the hierarchy, who
leave the most offspring.

Although the baboon and human lines of descent split apart some 30
million years ago, the species have much in common. Both are
primates whose ancestors came down from the trees and learned to
survive on the ground in large social groups. The baboon mind may
therefore shed considerable light on the early stages of the
evolution of the human mind.

In some of their playback experiments, Dr. Cheney and Dr. Seyfarth
have tested baboons knowledge of where everyone stands in the
hierarchy. In a typical interaction, a dominant baboon gives a
threat grunt, and its inferior screams. From their library of
recorded baboon sounds, the researchers can fabricate a sequence in
which an inferior baboons threat grunt is followed by a superiors
scream.

Baboons pay little attention when a normal interaction is played to
them but show surprise when they hear the fabricated sequence
implying their social world has been turned upside down.

This simple reaction says a lot about what is going in the baboons
mind. That the animal can construe A dominates B, and distinguish
it from B dominates A, means it must be able to break a stream of
sounds down into separate elements, recognize the meaning of each,
and combine the meanings into a sentence-like thought.

Thats what we do when we parse a sentence, Dr. Seyfarth said. Human
language seems unique because no other species is capable of
anything like speech. But when it comes to perceiving and
deconstructing sounds, as opposed to making them, baboons ability
seems much more language-like.

Assuming that early humans inherited the same ability from their
joint ancestor with baboons, then when humans first started to
combine sounds in the beginning of spoken language, their listeners
were all ready to perceive them, Dr. Seyfarth said.

Baboons may be good at perceiving and thinking in a combinative
way, but their vocal output consists of single sounds that are
never combined, like greeting grunts, the females sexual whoop and
the males competitive wahoo! cry. Why did language, expressed in
combinations of sounds, evolve in humans but not in baboons?

A possible key to the puzzle lies in what animal psychologists call
theory of mind, the ability to infer what another animal does or
does not know. Baboons seem to have a very feeble theory of mind.
When they cross from one island to another, ever fearful of
crocodiles, the adults will often go first, leaving the juveniles
fretting at the waters edge. However much the young baboons call,
their mothers never come back to help, as if unable to divine their
childrens predicament.

But people have a very strong ability to recognize the mental
states of others, and this could have prompted a desire to
communicate that drove the evolution of language. If I know you
dont know something, I am highly motivated to communicate it, Dr.
Seyfarth said.

It is far from clear why humans acquired a strong theory of mind
faculty and baboons did not. Another difference between the two
species is brain size. Some biologists have suggested that the
demands of social living were the evolutionary pressure that
enhanced the size of the brain. But the largest brains occur in
chimpanzees and humans, who live in smaller groups than baboons.

But both chimps and humans use tools. Possibly social life drove
the evolution of the primate brain to a certain point, and the
stimulus of tool use then took over. Use of tools would have
spurred communication, as the owner of a tool explained to others
how to use it. But that requires a theory of mind, and Dr. Cheney
and Dr. Seyfarth are skeptical of claims that chimpanzees have a
theory of mind, in part because the experiments supporting that
position have been conducted on captive chimps. Its bewildering to
us that none of the people who study ape cognition have been
motivated to study wild chimpanzees, Dr. Cheney said.

Baboons provide you with an example of what sort of social and
cognitive complexity is possible in the absence of language and a
theory of mind, she said. The selective forces that gave rise to
our large brains and our full-blown theory of mind remain
mysterious, at least to us.