Why do giraffes have long necks?

Charles Darwin, famous naturalist whose theory of evolution is now constitutive of modern biology, already took the giraffes in the XIXe century as an example of natural selection. According to him, individuals of this species with the longest necks foraged more easily by grabbing food from high branches. This advantage would have led them to reproduce more until the long neck became part of the species.

Only today, reports Smithsonian Magazine, has a complementary explanation to this emerged. A team of paleontologists and paleobiologists has just published a new study in the magazine Science, which suggests that the elongated neck of giraffes could also be due to the result of intense competition between individuals fighting over sexual partners.

In 1996, unusual skulls and remains of cervical vertebrae were discovered in China, which would have belonged to an indirect ancestor or cousin of giraffes. For a long time, scientists called this strange animal “guài shòu” (“strange beast”). They just gave it an official name: “Discokeryx xiezhi” and reconstructed what it might have looked like around 16.9 million years ago.

A brawling cousin

Discokeryx xiezhi lived in what is now northern China, and fed on leafy plants. You can get an idea of ​​its appearance on the Smithsonian Magazine website: the size of a large sheep, it had a very robust skull and thick vertebrae. Scholars speculate that he used them to fight; and maybe were its head and neck joints the strongest and most complex of all mammals.

Comparing it to musk oxen and types of sheep that all use their heads to fight, scientists deduced that this giraffe could have probably beaten them all.

This discovery makes it possible to rethink the hypotheses on the reason for such an elongated neck in modern giraffes. The males of this species do not really use their skull today to fight but their neck, in the same perspective of sexual competition as their cousins. This type of confrontation could therefore be a factor in the evolution of their necks.

This does not explain, however, if we consider the hypothesis of the struggle for sexual partners between males, why females also have such long necks. This is the reason why scientists believe that there are a multitude of explanatory factors for this evolution. According to Rob Simmons in any case, biologist and ecologist at the University of Cape Town, “If Darwin were alive, he would be overthrown by advances in evolutionary research.”

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