the-BA : Computer monkeys

Macaques. Image acknowledgement: Bernard Thierry, CNRS

By Wendy Barnaby

A juvenile macaque approaches a dominant male. The male is sitting next to a female holding a newborn infant.

The juvenile scares the infant, which tries to hide in its mother's stomach. The male hits the juvenile so that it lands several feet away. The juvenile turns around, approaches the male again and is reconciled with it. The two hug each other.

This is the sort of behaviour which can be understood by computer modelling as well as by traditional observation of macaques, Dr Joanna Bryson of the University of Bath told the BA Festival of Science in York on Tuesday.

By modelling the animals' behaviour, she and her colleagues have been able to correct theories about how macaques interact.

The models create "agents" programmed with rules. The researchers can compare the way they work with the behaviour observed.

"This kind of agent-based modelling is really a new way of doing science," said Dr Bryson.

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

"Agent-based modelling techniques let us invent and remove behaviours to test explanations of what we see in nature.

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

Macaques live in two different sorts of societies. Despotic groups have a clear hierarchy of rankings. The animal fight rarely but violently when they do. Egalitarian groups (such as the one illustrated above) have a less rigid hierarchy and more, but less serious, spats.

Dr Bryson and her colleagues used a model to correct a previous model about the differences between these groups.

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

"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.

"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 simply explanation for what we see in the wild, and it explains why some groups have a different range of behaviours than others," she said.

Dr Bryson describes her research in a special edition of Philosophical Transactions of the Royal Society B (September 2007), which deals with various aspects of modelling natural action selection.

Read more news coverage at the Telegraph and online at Science Daily and WebIndia123.

Image acknowledgement: Bernard Thierry, CNRS