Altruism varies under different conditions

Washington, May 1: Altruism wears different hats under different circumstances, says a new math model that pinpoints the conditions favouring one form of altruism over another.

The model predicts that creatures will help each other in different ways depending on whether key resources such as food and habitat are scarce or abundant, say researchers.

Examples of creatures caring for others at the expense of themselves are well-known. Ants, bees, and some birds will help their relatives raise kids rather than raise kids of their own.

Even the simplest of social creatures, such as single-celled bacteria and slime moulds and other microbes, sometimes sacrifice their own well-being for the sake of their group.

Most math models of how cooperation comes to be assume that all forms of altruism provide similar perks. But the benefits of altruism are different for different behaviours, said study author Michael Wade, professor at Indiana University and visiting scholar at the National Evolutionary Synthesis Centre (NESC), Durham, North Carolina.

For example, some creatures cooperate for the sake of defence, others to find food, and yet others to care for young, he explained, according to an Indiana and NESC statement.

Wade and collaborator J. David Van Dyken of Indiana show that when key local resources such as food or habitat are scarce, altruistic behaviours that provide more of those resources, or that use them more efficiently, will be favoured.

Think of lions banding together to hunt and take down prey, or honey bees sharing their findings as they forage for food. Many animals guide other members of their group to newly discovered meals, or bring food back to share with their nest mates.

But when resources are abundant, altruistic behaviours that help other individuals live longer, or produce more offspring, will give organisms an edge. Animals such as songbirds, ungulates and chimpanzees, for example, make alarm calls to warn nearby group members of approaching predators, braving danger to protect others.

“But the bottom line is that the way creatures are likely to help each other when times are tight is different from how they’re likely to help each other in times of plenty,” Wade said.