THE mating habits of a small lizard are challenging a central tenet of evolutionary theory. One of the best explanations for why animals cooperate is that they help each other because they are closely related, a concept known as kin selection. It now appears that this isn’t always the case. Male side-blotched lizards cooperate with other males who are genetically similar, but are not related.
It’s a subtle but extraordinarily significant difference. Because the behaviour can’t be explained by kin selection, biologists may have to radically redefine the theory, or invoke a new form of evolutionary selection to explain why the lizards act this way. It…
