Most of us have marveled at the giraffe, taking the time to admire the reach of its neck, which marks it as one of the strangest and most unique looking animals in the modern world. And most of us, at one time or another, have wondered why they have those necks and how exactly they came about.
This question is often used to illustrate evolution by natural selection — longer necks means easier access to taller trees and more food. This answer, however, is probably too simplistic, as a new study may have discovered.
How their necks became so long has an obvious enough explanation: The neck bones lengthened over generations, for whatever reason. However, a new study illustrates that even the obvious answer can hide complexities.
The study, which is entitled “Fossil evidence and stages of elongation of the Giraffa camelopardalis neck” was published in the journal “Royal Society Open Science” and looks specifically at how and when the cervical vertebrae C3 elongated.
It turns out the C3 experienced greater than normal, or allometric, growth in the direction of the head for several generations, starting around seven million years ago. It then experienced similar growth toward the shoulders around one million years ago.
That secondary backward growth has only occurred in the giraffe and produced the species’ signature long necks.
By contrast, the giraffe’s only living sister species, the okapi, have reduced cervical bone material, which in turn causes their necks to become shorter than normal.
The question of why this happened remains in the air. As for the question of how it happened, the answer will likely be complex and intricate, as evolutionary development continues to defy simple answers.