The size of giraffe necks has become one of nature’s great mysteries. For this reason, these mammals have ended up being the protagonists of studies in all kinds of scientific disciplines. Many theories have tried to explain this rare feature. At first, the French naturalist Jean-Baptiste de Lamarck (1744-1829) proposed the solution that seemed the most logical. The necks were so long so that the giraffes could reach the food in the treetops and thus developed this evolutionary advantage over other animals.
But science has shown that the answer may not be so easy. The recent discovery of a fossil of a primitive species points to another possibility and that is that giraffes stretched out their necks for a much more basic reason: to gain the predilection of females to maintain their lineage.
This has been concluded by researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences in an article published in ‘Science’, after studying the characteristics of Discokeryx xiezhi, a strange primitive giraphoid found in the Asian country. After analyzing their bones, the scientists concluded that the neck of the giraffes would have evolved in this way to be able to compete against other males during courtship.
And it is that, for a male to become the most important within the hierarchy of the tower (as the packs are known) -and therefore be the most coveted to procreate with the females- he must prove to be stronger than the males. the rest. In this sense, this study concludes that Genetically having a longer neck allows them to cause greater damage to their opponents.
During the fierce courtship fights, male giraffes fight each other throwing their heavy heads (very robust and full of bumps) towards the weakest parts of their opponents, in order to knock them out of the reproductive game.
The fossils in this study were found in strata from the early Miocene—corresponding to about 17 million years old—in the northern Junggar Basin in China. A complete skull and four cervical vertebrae of this protogiraffe were found at the site, which they named Discokeryx xiezhi.
“The individual had many characteristics that make it unique among mammals,” highlights Tao Deng, a professor at the Institute. The feature that most surprised them about this animal is that it had a single protuberance instead of two (as current giraffes usually have). “It’s a big disc-shaped ossicon in the middle of his head,” says Deng. In fact, this unicorn It is what has given it that peculiar name, because in Chinese mythology the xiezhi is a creature with a single horn.
The Discokeryx xiezhi It also has very robust cervicals, as well as complex joints that join the head and neck. These characteristics have a close relationship, according to research, with head-to-head impacts at high speeds. In fact, andThis animal is probably the vertebrate best adapted to cranial collisions.
“Both live giraffes and Discokeryx xiezhi they belong to the Giraffoidea group”, explains the author of the article Shiqi Wang. For this reason, although the morphology of their skulls and necks differ quite a bit, “both are associated with male courtship fights and both evolved in an extreme direction”, assures the investigator.
Apart from dissecting the behavior of the Discokeryx xiezhi, The research team also compared the horns of various groups of ruminants, including giraffes, cattle, sheep, deer and pronghorn. They found that giraffes have a much greater variety of bumps than other animals, which, in the eyes of the researchers, indicates that courtship fights “are more intense and diverse” in other similar animals.
After studying the enamel of their teeth, scientists concluded that Discokeryx xiezhi it lived in open grasslands and may have migrated at a specific season. At the time, 17 million years ago, the grassland ecosystem was very arid and less comfortable than the forest. Hence the researchers believe that this violent struggle to mate may be related to the climatic stress they suffered.
Seven million years ago, when the ancestors of the giraffes appeared, the environment was very similar. The East African Plateau changed abruptly from a forested environment to an open grassland, thus The first giraffes also had to find a way to adapt to the changes and this was to attack competitors with their long necks in order to mate.
These extreme struggles, coupled with sexual selection, caused rapid elongation of the giraffe’s neck over a period of two million years to finally become the giraffes we know today.
Reference study: https://dx.doi.org/10.1126/science.abl8316
Environment section contact: firstname.lastname@example.org