[tt] Primate behavior explained by computer 'agents'

[Michael LaTorra]

Primate behavior explained by computer 'agents'

The complex behaviour of primates can be understood using
artificially-intelligent computer `agents' that mimic their
actions, shows new research published in a special edition of
Philosophical Transactions of the Royal Society B and presented at the
BA Festival of Science in York.
Scientists using agents programmed with simple instructions to work out
why some primate groups are `despotic' whilst others are
`egalitarian' - overturning previous theories developed by
primatologists.

They have also found support for an existing theory of how dominant
macaques make it to the safer positions at the middle of their troop
without seeming to be pre-occupied with getting there.

Using agents programmed with two rules – stay in a group for safety
and pester subordinates until they move away – scientists found that
their more dominant agents would make their way to the centre of the
group.

This desire to stay in a group and pick on subordinates could be an
evolutionary mechanism that helps protect the more dominant and
successful individuals in a group, they suggest.

"This kind of agent-based modelling is really a new way of doing
science," said Dr Joanna Bryson from the University of Bath who led
the study and is one of the editors of the Philosophical Transactions
special edition.

"Previously scientists have been limited to trying to understand
animal behaviour by making observations and then developing theories
that fit.

"Now we can test these theories using agents to give us a better
understanding of complex behaviours.

"This work shows that agent models are an ordinary part of
scientific theory building. We confirmed and extended previous work on
spatial location of dominant animals, while showing where some theories
got it wrong – in this case a theory put forward for why macaques
form either despotic or egalitarian troops."

Whilst there is no hierarchical structure in egalitarian groups there
tends to be more fighting, although it is less violent, than in despotic
groups.

Primatologists noticed that egalitarian groups tend to spend more time
preening and hugging each other after fighting, leading them to
speculate that the two different types of society evolved following the
development of some groups' ability to `reconcile'.

"Agent-based modelling techniques let us invent and remove
behaviours to test the explanations of what we see in nature," said
Dr Bryson, from the University's Department of Computer Science.

"Using modelling you can vary the external environmental factors to
see if they have any effect on behaviour. You can do this for many
generations in a few hours and see whether new behaviour is
adaptive."

More recent work by Dr Bryson and graduate student Hagen Lehmann has
shown a new explanation for the theory they had previously overturned.

"By changing the amount of space between troop members, you can
create models of despotic and egalitarian groups of agents," said Dr
Bryson.

"Then you can show that the despotic agents do better in the
conditions we find despotic macaques in the wild. The same holds for
egalitarian macaques

"The violence and lack of reconciliation in despotic groups comes
down to the fact that they don't like living on top of each other.

"This creates more space for the troop so they can find more food.

"But by hugging and making up after fights, the egalitarians spend
more time close to each other. This makes them safer in environments
where there are predators.

"This is a simple explanation for what we see in the wild, and it
explains why some groups have a different range of behaviours than
another."

Source: University of Bath http://www.physorg.com/news108713129.html
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