If natural selection can be summarised as “survival of the fittest”, how is it that some animals have evolved features that seem to be rather unhelpful to their survival? Deer antlers, peacock tails and babirusa tusks do not help an animal to stay alive. Darwin asked a similar question in The Origin of Species, and also came up with an answer – sexual selection.
Sexual selection is a sub-set of natural selection, where the driving force is not on the animal to survive, but instead to have the most descendants. It is the mechanism by which species evolve weapons that help them fight off rivals; ornaments that make them more attractive to the opposite sex; or behaviours that ensure sexual encounters result in more or fitter babies. One of the best examples of absurdly ornamented animals are male birds-of-paradise. (more…)