Ever wondered how to pick the fittest mate? If you\'re a rhino beetle, choose the male with the biggest horns. Douglas Emlen from the University of Montana in Missoula and colleagues have shown that the size of the animals\' antler-like ornamentation reflects their nutrition and physical health. By conducting gene-silencing experiments, they found that insulin levels, which depend on factors such as diet, stress and infection, affect the growth of a male\'s horns. Whereas the size of other structures, like genitals and wings, are relatively constant across male beetles, the size of their horns varies greatly. Some males have tiny bumps whereas others have sprawling ornamentation, which can be an advantage when competing for females, as shown in the video above. Males are seen using their horns to get closer to a potential mate by flicking their rivals off a tree. They\'re also used as a weapon when males battle for a prized female. From : New Scientist