The evolution of even-toed ungulates: How the giraffe got its long neck – Wikipedia

The giraffe’s extremely long neck is likely an adaptation for its fighting behavior with other members of the same species. An international research team deduced this from examining the fossil remains of an ancient giraffe. These animals banged their heads together during battles and later developed a protective covering and extremely strong cervical vertebrae, scientists reported in Science.

The long necks of today’s giraffes could have evolved in a similar way. They don’t bang their heads against each other as their ancestors did, but bulls use their muscular necks to fight for their mating privileges.

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Animals exhibit a variety of combative behaviors

Co-author Manuela Eaglestorfer of the Museum of Natural History in Mainz explains the popular notion that long necks only evolved in the course of evolution because animals used them to reach leaves at the top of trees that might not go far enough. The State Natural History Collection Rhineland-Palatinate. “Maybe this is just a side effect, and combat strategy is the main reason for the evolution of the Long Neck.”

As a ruminant specialist, Aiglstorfer was part of the Shi-Qi Wang team at the Chinese Academy of Sciences in Beijing. Researchers examined the fossil remains of an animal that lived in what is now northern China about 17 million years ago: Discokeryx xiezhi, named after the mythical creature of the Asian rhinoceros “Xiezhi”. Eaglestorfer explained that analysis of the bones showed that they belonged to the group of giraffes. “This group was more diverse than it is today.” For example, the animals had different cranial limbs and also showed diverse fighting behavior.

Illustration: In the course of evolution, giraffe-like animals have also evolved new forms of ritual battles between bulls…Photo: Wang Yu, Guo Xiaokong

Investigations proved that Discokeryx The cervical vertebrae are very thick and strong. This allowed the animals to absorb the strong vibrations, as shown in the models. On their heads they wore a thick disk-shaped structure, which, in turn, was probably endowed with a kind of horn. Her neck was not exceptionally long.

Researchers suspect that the animals bang their heads together in a similar way to caribou or musk oxen today. Such fights can also occur when courting females. Indeed, the primitive giraffe’s vertebral structure was better adapted to superpowers than in today’s animals fighting in this way, the researchers wrote.

Giraffes today live on the African continent. Despite the very long neck, which is about two meters in length, the cervical spine consists of only seven vertebrae, as in most mammals. “The cervical vertebrae of modern giraffes have a completely different structure than those of Discokeryx, they are aligned for length,” says Aiglstorfer. Why animals developed such long necks during evolution has preoccupied scientists for centuries.

Advantages of fitness evolving

Some researchers hypothesize that sexual selection led to evolution: males with a strong, long neck win battles for females more often and pass their genes on to the next generation more often.

The theory that the advantages of obtaining food are more important is more well-known: evolutionary biologist Jean-Baptiste Lamarck suspected that the neck of a giraffe had stretched over its lifetime because it had always stretched leaves that grew so high. According to Lamarck, the newly acquired property was passed on to the sons. This theory has since been disproved because acquired adaptations do not affect the genes that underlie the inheritance of physical traits in this way.

The most common hypothesis today dates back to Charles Darwin’s theory of evolution. According to this, individuals with a particularly long neck are born again and again by chance. Because they have access to more food than their short-necked counterparts, they have a better chance of survival and more offspring, which they pass on on the genetic basis of the long neck. This is how the trait is expressed and the hereditary disposition predominates in the set of genes.

“Giraffes today and Discokeryx xiezhi “It belongs to the group of giraffes,” says Shi Zhi Wang. “Although the shapes of the skull and neck are very different, they are both related to male courtship fighting, and both have evolved in an extreme direction.”

Eaglestorfer says the findings do not refute a link to the diet. “But we are showing that in ruminants there can also be other important influences that affect the structure of the cervical spine.”

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