Maths used to explain benefits of co-operation

Computer simulations and mathematical models have been used by a university zoologist to explain an important characteristic of human behaviour which appears to have been vital in our evolution.

Professor Martin Nowak (pictured left), Professor of Mathematical Biology in the University Zoology Department, and Professor Karl Sigmund, Professor of Mathematics at the University of Vienna, have developed a mathematical theory to explain co-operation between individuals.

Professor Nowak said: `The Darwinian theory of evolution is based on survival of the fittest and severe competition between individuals. Co-operation, or altruistic behaviour, therefore requires a special explanation.'

It is argued that co-operation between people who are not related is based on the principle `I help you, but I expect that we will meet again and then you will help me.' But this is only part of the story, Professor Nowak said, because in order to work, this requires repeated encounters between the same two individuals or `direct reciprocity'.

Professor Nowak and Professor Sigmund built a computer model of a community to examine the human interactions which are not based in the expectation of further meetings and direct repayment, but on `indirect reciprocity'—the instinct to help someone one may never meet again.

Individuals lost points when they offered help and gained points when they received it. While `givers' initially lost, what they gained in goodwill from the community as a whole benefited them far more in the long run.

Writing in the journal Nayiute, they also argued that it pays to talk about your good deed because the cost of the seemingly `altruistic act' is offset by increasing the chance of becoming the recipient of such an act later.

Professor Nowak said: `It turns out that helping those that have helped others in the past increases the chance that someone may help you in the future because you are seen as a valuable community member. In other words, co-operation emerges according to the principle "give and you shall be given".'

He argues that solving the problem of co-operation among non-relatives was a decisive step in the evolution of the human species, and that the evolutionary success of humans is based, to a large extent, on their ability to help each other.

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