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Giraffes in Lake Nakuru National Park in Kenya
Photo: WLDavies/Getty Images/iStockphoto
Why are giraffes' necks so long?
If you are looking for answers, you will end up with the names of two famous researchers: Jean-Baptiste Lamarck and Charles Darwin.
Lamarck assumed that a giraffe's neck would stretch over the course of its life because it was always reaching for the tall leaves.
According to Lamarck, the newly acquired property was passed on to the offspring.
This theory has since been disproved because individual adaptations do not affect genes in this way.
Probably the most common opinion today about giraffe necks goes back to Darwin.
In accordance with his theory of evolution, he assumed that individuals with a particularly long neck would arise by chance again and again.
Since they can reach more food than conspecifics with a shorter neck, they have better chances of survival and more offspring.
This advantageous feature gradually prevailed.
But the biology books may soon need to be supplemented.
According to a new study, the giraffe's extremely long neck may be due to the animal's violent fighting behavior.
An international team of researchers concludes this from examining the fossil remains of an ancient giraffe.
These animals probably hit their heads against each other during fights and subsequently developed a protective hood on their heads and extremely robust cervical vertebrae, as the scientists report in the journal Science.
The extremely long necks of today's giraffes could have developed in a similar way.
They don't bang their heads against each other, but their impressively long and muscular necks do.
"The common notion that the long necks only developed in the course of evolution because the animals used them to reach leaves in the upper part of the trees may not go far enough," explains co-author Manuela Aiglstorfer from the Natural History Museum in Mainz and the State Collection for Natural History Rhineland-Palatinate.
"Perhaps this is just a side effect and combat strategy is the primary reason for the development of the long neck."
As a ruminant specialist, Aiglstorfer is part of Shi-Qi Wang's team at the Chinese Academy of Sciences in Beijing.
The researchers had examined the fossil remains of an animal that lived around 17 million years ago in what is now northern China: Discokeryx xiezhi, named after the Asian unicorn mythical creature Xiezhi.
Analysis of the bones showed that it was a member of the giraffe family, says Aiglstorfer.
“This group was much more diverse then than it is today.
For example, the animals had different skull appendages and also showed a variety of fighting behavior.«
No exceptionally long neck in primordial giraffe
The investigations showed that Discokeryx had extremely thick and robust cervical vertebrae.
This allowed the animals to absorb strong vibrations.
On their heads they wore a thick, disc-shaped structure, which in turn was probably provided with some kind of horn.
Her neck wasn't exceptionally long.
The researchers suspect that the animals rammed their heads against each other in a similar way to today's ibex or musk oxen.
Such fights could have occurred, for example, when courting a female.
In fact, the vertebral structure of the primordial giraffe was more effectively adapted to the great force than is the case in modern animals that fight in this way, the researchers write.
Today's giraffes live in Africa, their numbers have declined sharply in recent decades.
Despite the extremely long neck, around two meters long, their 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 in the course of evolution has occupied scientists for centuries.
Some researchers assume that sexual selection drove the development: Males with a strong, long neck therefore won fights more often for the females and passed their genes on to the next generation.
"Our investigation did not show that there is no connection between neck length and diet," says Aiglstorfer.
"But we show that in ruminants there can also be other significant influences that affect the structure of the cervical spine."
joe/dpa