A new study of the fossil remains of an early giraffe ancestor lends support to the intriguing idea that the extraordinarily long necks of modern giraffes evolved to aid fighting as well as feeding.
Long necks enable giraffes to feed on leaves beyond the reach of competitors. But they are also deployed during tussles for dominance, when males swing their armoured heads at each others’ bodies, with the neck serving as the long handle of a club, increasing the force of the blow.
Researchers at the Chinese Academy of Sciences have now shown that a 17-million-year-old giraffe ancestor, Discokeryx xiezhi, possessed helmet-like head armour and robust neck vertebrae, suggesting that head-to-head combat set scene for subsequent neck elongation.
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Robert Simmons of the University of Cape Town, who proposed the ‘necks for sex’ hypothesis in the 1990s, but was not involved in the latest research, says that the study presents “unequivocal evidence that the Discokeryx fossil is beautifully adapted to intense head clashes.
“It is not easy to distinguish the ‘feeding competition’ hypothesis from the ‘necks for sex’ idea and it is very likely that both have played a role in the evolution of the magnificent animals we see today.”
Andrew Kitchener, Principal Curator of Vertebrates at the National Museums Scotland, who was not involved in the study, says it’s not clear from the fossil whether the head armour was used aggressively or defensively, like a rhino’s horn. “I think we have to say the jury is still out.”
Read the full paper in Science.
Main image: male southern giraffes (Giraffa giraffa giraffa) fighting in Kruger National Park, South Africa. © Christian Vorhofer/Getty