Sexual selection

When males fight over females and not the other way around, it is due to the energy that the two sexes invest in their offspring. It is more demanding to produce an egg than a sperm cell, so it is very important for a female to be fertilized by the male with the best genes. She wants to mate with the strongest male, whereas males just want to mate with as many females as possible.

Over millions of years, the females’ choice of partner has led to the development of numerous qualities in males. The special qualities, such as the male peacock's tail, improve the individual’s likelihood of mating.

Over the ages, females have preferred males with long tails, and so, the males with the longest tails have been most successful fathering offspring. The result of the selection is the abnormal tail of modern peacocks. The plumage rivalry and other particular male characteristics ensure that only the genes of the biggest and strongest males are passed on to the next generation.