By Roger Highfield, Science Editor
09 Jul 2008
New hope that people around the world can work together to combat global warming has come from a new theoretical study.
A team has been using "game theory" - where mathematics is used to capture how people deal with each other - to show that a classic problem that undermines the ability of individuals to cooperate can be overcome, if people are diverse enough, as is the case when it comes to the 6.5 billion citizens of planet Earth.
Working together for the common good is crucial for progress in any society - not least for effectively addressing big issues such as recycling and tackling climate change. But there is a basic problem with how to make the public share responsibility for common problems, such as climate change.
This was most vividly illustrated by Prof Garrett Hardin, of the University of California, Santa Barbara, in his highly influential 1968 paper 'The tragedy of the commons'.
He used the example of a public pasture. Each herdsman will keep adding cows to a common field, because the benefit of an additional cow goes exclusively to the herdsman. Because the cost of overgrazing is shared by all, the pasture will end up ruined.
Mathematical models have confirmed that this is a profound problem, whether for coming together to fight climate change or pay taxes, but today, in the journal Nature, hope for cooperation is raised by Prof Jorge Pacheco of the University of Lisbon, who did the work there with Ms Marta Santos and Dr Francisco Santos from the Free University of Brussels.
Existing mathematical models treat individuals as equivalent, ignoring real-life diversity and population structure. So the team made the mathematics more realistic in this respect.
The team shows that, contrary to expectations, the temptation to cheat ("Why shouldn't I let others pay more for being green?") declines as society becomes more diverse.
Another discovery is that diversity also plays an important role in wealth distribution.
"Cooperation blooms whenever the act of giving is more important than the amount given," said Prof Pacheco.
The most important factor, he said, seems to be that people actually contribute to the public good.
"In particular, the fact that the wealthy minority contributes stimulates the contribution from the rest, who take them as role models," he said.
Prof Pacheco recalled the words of Anna Dreber and Prof Martin Nowak from Harvard University, leading game theorists, who stated that “preserving the global climate is the biggest public good dilemma ever, the one we cannot afford to lose."