A female may choose a male from several because he is attractive ... Looks are certainly important for the peacock, with his absurdly bright, burdensome train that he shows off to attract a ...

That is why, evolutionary biologists say, males are most often the ornamented sex. It is why the male peacock unfurls his dazzling train, why male guppies are adorned with bright orange and blue ...

This process explains the evolution of features such as peacock tails ... skeleton—common targets in male fights. The study authors hypothesized that human upper limbs may have evolved to ...