Please enter search term

How Did Giraffes Get Their Long Necks?

January 12, 2016

Story at-a-glance

  • The giraffe’s oldest known ancestor, which lived about 25 million years ago, already showed signs of neck elongation
  • Fossil analysis revealed that giraffes’ vertebrae started out elongating in the front and later elongated in the back
  • Why giraffes developed such a long neck remains a mystery, but food availability and/or sexual selection may have played a role

By Dr. Becker

When you think of a giraffe, the first feature that probably comes to mind is the long neck. New research suggests, however, that giraffes are not the only species to have an elongated neck (though they do have the longest).

Researchers at the New York Institute of Technology College of Osteopathic Medicine analyzed neck vertebrae from 11 species (including 9 that are extinct, giraffes and okapi, which belong to the same family as giraffes).

Giraffes' oldest known ancestor, Prodremotherium, which lived about 25 million years ago, already showed signs of neck elongation, according to the study.1 "Neck length, the most distinguishing and popular attribute of Giraffa, is apparently not a defining feature of the family," researchers wrote.2

About 16 million years ago, Canthumeryx, another primitive giraffe relative roamed the earth. It, too, had signs of elongation in its neck. At this point, the family split into two branches.

One side, which led to the modern-day okapi, had necks that grew shorter over time. The other side, which led to modern giraffes, had necks that grew longer.

Another giraffe ancestor, Samotherian, which lived about seven million years ago, also had an elongated neck, although it was still much shorter than modern-day giraffe necks.

Interestingly, the fossil analysis revealed that the giraffes' vertebrae started out elongating in the front and later elongated in the back. As reported by Live Science:3

"Now that researchers know that the giraffe's neck is at least 16 million years in the making, they can continue trying to figure out what drove the evolution toward longer necks."

Why Did Giraffes Develop Such Long Necks?

Giraffes, the world's tallest mammals, may reach 14 to 19 feet in height and up to 2,800 pounds in weight. Their long necks give them a unique advantage in spotting predators at a great distance as well as allow them to feast on leaves from treetops that other animals can't reach.

The latter is one of the leading theories for why giraffes developed long necks; the feature allows them to reach food resources high in the treetops, which are unreachable to many other species.

Still, other animals are able to feed in treetops without a similarly long neck (such as certain species of goats, for instance). So this explanation doesn't entirely explain why giraffes have long necks.

Another theory has to do with sexual selection, since female giraffes seem to prefer male giraffes with the longest necks. A longer neck also gives male giraffes an advantage during battle.

Male giraffes fight with one another by butting necks and heads. These displays don't typically result in injury and end when one animal gives up and walks away.4 However, female giraffes tend to mate with the winners of such fights, which would have encouraged the evolution of longer necks.5

Adding to the mystery, the giraffe's long neck can also be an encumbrance, especially when taking a drink. In order to reach a watering hole, giraffes must spread their legs wide and bend down awkwardly, making them vulnerable to predators.

In this way, Craig Holdrege, Ph.D., director of The Nature Institute, asked why no one has considered that the giraffe's neck is actually short (at least in relation to the rest of its body):6

"I sometimes wonder why no one has maintained that the giraffe has, in reality, a short neck. If you observe a giraffe drinking or, as they occasionally do, grazing close to the ground, then you know what I mean …

Giraffes do not drink often, but when they do, they have to either splay their forelegs to the side or bend their forelegs strongly at the wrist joint. Both procedures take time and are awkward for the giraffe. But only in this way can it get the tip of its mouth down to the surface of the water.

So, looked at from the perspective of drinking, the giraffe has a very short neck. Antelopes and zebras reach the ground without bending their legs, and the long-legged elephant has its trunk to compensate for its short neck.

Only the giraffe (and its rain forest relative, the Okapi) have necks that are so short relative to their legs and chest that they must splay or bend their legs. So why hasn't the giraffe become famous for its manifestly short neck?

Why don't we have evolutionary hypotheses explaining how the giraffe got its short neck? … Whether the neck is long or short depends on our perspective and on the behavioral or anatomical context we are focusing on.

We only understand the giraffe when we view it from various perspectives and let the giraffe show different aspects of its being. The moment we focus solely on the 'long neck' — and on it solely in terms of a food-gathering or some other strategy — we've lost the reality of the giraffe."

Giraffe Population Drops 40 Percent

Giraffes are listed as a species of "least concern," according to the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species. However, the list may need to be updated after the Giraffe Conservation Foundation reported giraffe populations are seriously declining.

In the last 15 years, the giraffe population in Africa has dropped about 40 percent, from 140,000 to 80,000 animals. Dr. Julian Fennessy, director of the Giraffe Conservation Foundation, called it a "silent extinction." Discovery News reported:7

"Unfortunately for giraffes, their skin can be used to make several clothing items, and countries such as Tanzania have come to believe eating parts of the animal can cure HIV-AIDS. Hunters, for their part, can earn money from the animal's meat without a great deal of effort."

Giraffe habitat is also being threatened by agriculture, settlement expansions and the construction of roads. As acacia trees, giraffes' main food source, are destroyed, wild giraffe habitat and populations in the wild are shrinking.

Organizations like the African Wildlife Foundation are working with local communities to implement sustainable practices for agricultural and settlement growth. They're also working on reforestation projects in West Africa to plant more acacia trees and allow giraffes to expand their habitats.8

Previous ArticleExperts Peek Into the Private World of a Giant Panda, and Guess What They Found? Next ArticleBaby Sloths Learn to Climb Using Rocking Chairs

Sources and References

  • 1 Royal Society Open Science October 7, 2015
  • 2 Science News October 7, 2015
  • 3, 5 Live Science October 7, 2015
  • 4 National Geographic, Giraffes
  • 6 The Nature Institute Fall 2003, pp 14-19
  • 7 Discovery News December 3, 2014
  • 8 African Wildlife Foundation, Giraffes
  • Most Popular