How the giraffe got its neck is a question people have asked for centuries, both in science labs and ancient myths. Now, thanks to a study of fossils from giraffe ancestors, researchers have finally discovered just how giraffe necks grew so long.
Scientists have long puzzled over why giraffes would grow such an ungainly extremity. After all, the only other living member of the giraffe family, the okapi, has a stubby neck and munches on leaves that grow close to the ground. So researchers from the New York Institute of Technology set out to solve the mystery, Laura Geggel writes for Live Science.
By examining vertebrae from the necks of 71 different animals belonging to 11 different species (including current-day giraffes), lead author Melinda Danowitz and her colleagues discovered that the giraffe’s ancestors already had slightly longer necks than expected, Brian Switek reports for National Geographic. That means that the lengthening started over 16 million years ago, before the subgrouping for giraffes—giraffidae—broke from other two-toed beasts.
At about 16 million years ago, the giraffe lineage split: On one side the vertebrae shrunk overtime while on the other they lengthened. This is why the modern giraffe and okapi have such different statures, Geggel writes.
The first “truly long-necked giraffe” only appeared about 7.5 million years ago, Switek writes, and it wasn't a short process. Generation after generation, the neck bones of most giraffe ancestors lengthened from either the top or the bottom. But the modern long-necked giraffe was the only one whose vertebrae stretched in both directions to produce the lengthy physique that zoo-goers today know and love.
Even more interesting, the giraffe's necks didn't elongated smoothly, but in fits and spurts over millions of years. As Switek writes:
If you could assemble all these fossil bits and pieces into a short film replaying giraffe evolution, you wouldn’t end up with the smooth transformation of a small-statured herbivore into a towering, checkered browser. There’d be starts and stops and side stories, the ending not being a goal but a happenstance.
From a lengthy history of evolutionary flukes emerges the giraffe.