In the end, only the largest, fittest, best-armed males prevail in the competition for reproduction. For the fallow deer in Phoenix Park, one male in ten managed to mate at all, and the vast majority of copulations (73 percent) went to just 3 percent of the bucks. Such extremes in reproductive success—90 percent failure rates and extraordinary success by just a very few individuals—lead to intense sexual selection, and much of this is directed toward bulk, stamina, and big weapons.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 323