Can animals work for the common good?

Harsh environments force animals to act nice

Posted Jan 14, 2011

Nature is not as red in tooth and claw as we used to think. Primates are nice to each other nine times as often as they are nasty.

Now animal behaviorists are confronting more and more evidence that unrelated animals help each other out in critical ways, whether by sharing heat on a cold day (emperor penguins) or sharing food (vampire bats).

Animals can work together for the common good. Mule deer females look out for each other's fawns when the mother is absent grazing and predators happen by, for instance.

Creating public goods
Darwinian cynics view life as a constant struggle to obtain resources that are scarce, yet essential for successful reproduction. This gladiatorial view of life is seriously incomplete. Social animals sometimes get together to tackle problems of survival that they cannot master alone by creating a shared advantage (or public goods).

Emperor penguins huddle together on cold days thereby greatly reducing the amount of food energy required to stay warm. Without such joint protection of body heat, they could not breed on the Antarctic ice (see movie, March of the Penguins).

Animals cooperate when they face very difficult problems. Apart from extreme climates, another common dilemma is the attempts of predators to feast on defenseless young. Many small birds team up to attack their prospective predators in a gutsy maneuver known as a mobbing attack.

When mule deer females go out to graze, they leave their fawns behind. To a Darwinian cynic, this poses an irresistible opportunity. When a predator visits, all a female has to do to protect her own young is to draw the predator's attention to the resting fawn of her absent companion.

Yet the female mule deer do the opposite. They protect all of the fawns in the vicinity (even those of another species, white-tailed deer, that never return the favor) by attacking the predator. When this joint defense of the young by mule deer females was first published a few years ago (1), it garnered a lot of press attention. Yet it remains unexplained.

How could such selfless behavior possibly evolve? We can rule out kin selection given that the females are mostly unrelated. Reciprocal altruism (you scratch my back, I'll scratch yours) is unlikely for several good reasons. The absent female does not know which individuals helped her so as to repay them. The system persists despite cheating by white-tailed deer that drop their young off to be protected in the mule deer "creche." Moreover, young adult females that have no fawn yet also protect unrelated fawns.

To the extent that protecting all of the fawns is an effective anti-predator strategy, this cooperative behavior could have evolved via individual selection. By defending the young of other females, a mule deer weakens the threat of local predators. A coyote that is denied a meal today is less likely to return tomorrow for her own offspring.

Attacking the predator yields a public good, namely, security against future attacks. Mule deer females that drive away predators are thus more likely to raise their offspring to maturity than those that stand idly by. (White-tailed deer do not do this because they hide their young in dense underbrush rather than sticking it to the predator).

Sharing body heat on a cold day is not the only situation in which the interests of the individual and those of the group line up exactly. Contrary to the views of Darwinian cynics, animals are capable of working together for the common good. Natural selection compels them to do so.

1.Lingle, S., et al. (2007). Altruism and recognition in the antipredator defense of deer:Why mule deer help nonoffspring fawns. Animal Behavior, 73, 907-916.