New research suggests that fighting between males, the result of reproductive pressure, contributed to the evolution of the species in its current form.
Giraffe’s long neck (giraffe camelopardalis) is an evolutionary achievement as well as a biomechanical mystery. It consists of seven vertebrae, the same number as humans, although greatly expanded and the joints that allow it to move are more complex. Furthermore, in order for blood to reach the brain, the heart must pump it to a height of two meters, a task that is only possible for an abnormal heart structure, a blood pressure that doubles as blood vessels with humans and blood vessels. gives. Very thick walls.
Since the French naturalist Jean-Baptiste Lamarck (1744–1829), scientists have proposed various hypotheses about the evolutionary process that caused giraffes to lengthen their necks. Many believe that the engine of evolution was the need to reach vegetation in the upper reaches of trees, which was the result of competition with other ruminants. But other researchers put forward alternative explanations, such as a better distribution of heat that would allow giraffes to cope with the extreme climate of their habitat. fossils of the present A distant relative of the giraffe, which lived about 17 million years agoReveal new keys to the evolution of this species.
According to a study led by researchers from the Chinese Academy of Sciences, competition between males during courtship will be one of the main forces that drove the development of their long necks. The results are published this Thursday in the journal science, Specifically, this a. has a complete skull and four cervical vertebrae discocryx xiezhiThe remains of which date back to the early Miocene and were found north of the Junggar Basin in the Chinese province of Xinjiang.
,D. Zhizi Exhibited many characteristics unique among mammals, such as the development of an ossicle [protuberancia sea] disc-shaped in the center of the head,” explains Professor Deng Tao, one of the paper’s authors. “Like modern giraffes, it belonged to the superfamily Giraffoidea and, Although their skull and neck morphology are different, in both species they are associated with male courtship fights and both have evolved in an extreme direction.” That small horn represented a creature from Chinese mythology, the authors of the Zizi. who have worked to baptize it. Species.
The study combines elements of behavioral observation of giraffes with physical comparisons of different ruminant species, including Discrocks. The authors point out that the length of a giraffe’s neck is directly related to social hierarchy, in addition to being a weapon in courtship fights. And he believes these dynamics may be the key to the giraffe’s evolutionary mystery. Males use their necks, which are two to three meters long, to launch their heavy skulls – themselves armed with ossicles and osteomas – against their rivals; The longer the neck, the more damage the opponent inflicts.
The authors found that the diversity of bony protuberances in giraffes and their closest evolutionary relatives is much greater than in other groups, with a tendency for large differences in their morphology, indicating that courtship fights in giraffes are more intense and diverse. giraffe ruminants other than giraffes, on the other hand, cervical vertebrae discocryx xiezhi They are particularly strong and have the most complex joints between the head and neck and between the cervical vertebrae in mammals. The team concluded that these joints were specially adapted for high-velocity head-to-head impacts, a structure far more efficient than that of any living animal, such as a musk ox, a species-specific Well adapted to impact on the head.
The research team further analyzed the ecological environment D. Zhizi, In the Miocene, the Xinjiang region was drier than other regions of the planet during the same period, as the Tibetan Plateau to the south rose rapidly, thus blocking the transfer of water vapor. “Stable isotopes of tooth enamel indicate that Discrockery lived in open grasslands and migrated seasonally,” explains Meng Jin, one of the authors.
Similarly, about seven million years ago the East African region also changed from a forest environment to a savanna landscape, and the giraffe’s direct ancestors had to adapt to the new changes in the same way as their evolutionary relative. , It is possible that during this period among the ancestors of giraffes, males developed a way of attacking their competitors more forcefully by twisting their necks and heads.
These violent conflicts, driven by the pressure of sexual selection, rapidly elongated the giraffe’s neck to its present form over a period of two million years. In addition, this evolutionary advantage allowed them to better adapt to feed on the highest branches of trees, ensuring their ecological status as compared to bovids and cervids.
according to the norms of