Why Giraffes Have Such Long Necks
Is it "necks for sex" or just for food?
Among the strangest proportions in the animal kingdom is the elongated neck of the giraffe. Scientists have long debated what led to the strange feature. Darwin figured it was to help giraffes snag food from high up in trees. A more recent idea suggested it was due to competition among males, who spar by swinging their powerful necks.
The “necks for sex” hypothesis seems a bit of a stretch based on new research published in the journal Mammalian Biology.
By analyzing the heights and proportions of giraffes, researchers found adult females have proportionally longer necks and longer primary body sections. And these dimensions come into play at a critical time in the lifecycle of a female giraffe.
“Giraffes are picky eaters — they eat the leaves of only a few tree species, and longer necks allow them to reach deeper into the trees to get the leaves no one else can,” said the study’s lead author, Doug Cavener, PhD, an evolutionary genetics researcher and professor of biology at Penn State. “Once females reach four or five years of age, they are almost always pregnant and lactating, so we think the increased nutritional demands of females drove the evolution of giraffes’ long necks.”
Male giraffes have thicker necks, the study revealed, which might have come about to offer advantages in tussles with other males. Also, being up to 40% larger than females, males have proportionally longer forelegs. This might help them in mating, which Cavener and colleagues describe as a “brief and challenging affair” for giraffes.
