Scientists have puzzled over the distinctive form of giraffes at least since Charles Darwin and Jean-Baptiste Lamarck (figuratively) butted heads over how the towering ungulates got their long necks.
The Darwinian theory still prevails, but which of the two processes —natural selection or sexual selection—plays a more important role still divides evolutionary biologists. A new study led by scientists at the Chinese Academy of Sciences published in the journal Science adds weight to the sexual selection hypothesis.
The discovery of the fossil of Discokeryx xiezhi, an ancient cousin of present-day giraffes (Giraffa camelopardalis) that roamed the earth around 17 million years ago, suggests long necks win giraffe mating wars.
“Their simple message is that sexual selection played a big role in one of the ancestors of the present-day giraffe, and thus it opens the door for other members of this diverse lineage to show sexually selected necks and heads,” said Rob Simmons, a behavioral ecologist at the University of Cape Town in South Africa. Giraffes are found only in east and southern Africa.
Simmons, along with Lue Scheepers, put forward the sexual selection hypothesis back in 1996.
Lead Image: A rendition of D. xiezhi head-to-head butting. Image courtesy of Xiao Cong Guo and Yu Wang.
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