Want to keep your partner? Better be cooperative

Mathematicians have tackled the question of why cooperative behaviour is common in many species when natural selection often favours those who do best for themselves rather than those who help others at their own cost. 

Don't be lonesome - Cooperation could be key to a successful partnership

Professor John McNamara and his group from the University of Bristol say that the cooperation has stemmed from choosy individuals. They have demonstrated that when individuals in a population are choosy about their partners, cooperativeness is rewarded and tends to increase.

To explore this issue, they created a computational model, which considers pairs of individuals who engage in a ‘game’. Each ‘player’ is characterised by their level of cooperativeness - how much effort one assigns to helping its partner, and their level of choosiness - the minimum cooperativeness an individual will put up with.

Professor McNamara said: “If the current partner is not cooperative enough the individual stops interacting with this partner and seeks a better partner, even though finding a new partner incurs costs.” 

In nature, it would be worth leaving a current partner to search for an upgrade only when there are better partners available and enough time to make the new relationship worthwhile. This explains why long-lived cooperative animals, like humans, often change partners throughout their lifetimes.

The mathematicians found that when individuals have high standards for prospective partners then cooperativeness is rewarded and that cooperativeness can evolve from initially uncooperative species.

The research is published in Nature and was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Deutsche Forschungsgemeinschaft.

By Leila Sattary