Giraffes have an unmistakable, awkward charm about them. But these megaherbivores can also be quite brutal. In intense bouts, male giraffes compete for dominance by steadying their legs and swinging their necks to deliver sledgehammer blows to each other with the stout ossicones atop their heads.

For a time, it seemed that this violent behavior might be the secret to why giraffes are so oddly proportioned. Sexual selection, rather than the quest to reach ever-higher foliage, was picked out as a possible explanation for the strange anatomy.

In a 1996 study, zoologists Robert Simmons and Lue Scheepers proposed that the “necking” competitions between males favored the evolution of ever-longer necks. Imagine an archaic population of short-necked giraffes that competed like their modern