Standing at 5.8 meters (19 feet), the giraffe is the tallest land animal thanks to its unusually long neck. But although the neck can be up to 1.8 meters long, giraffes are like most mammals, with only seven cervical vertebrae.
Nearly 17 million years ago, the ancestors of giraffes with short necks and thick skulls roamed Africa, Asia and even northern China.
This ancient species was named Samotherium. It was closely related to the modern giraffe, but was as small as a sheep, with a short neck similar to other land mammals of the same size.
Fossil analysis shows that the top of Samotherium’s skull was covered with horny substance, the same tissue found in the horns of butting ungulates like cows and sheep. The researchers speculate that male Samotheriums also use “head shields” to butt each other when competing for mates.
In short, in the olden days, the giraffe’s ancestors were a species with a relatively different character from that of today’s descendants. So what developments drove the unique long necks of modern giraffes?
According to Darwin’s theory of natural selection
To scientists, the neck of a giraffe is truly a magical creature. Although it has a length of nearly 2 meters, this neck also consists of only seven vertebrae like the human neck. The question of how such a structure could have developed has long puzzled the scientific community.
As with evolutionary problems, the conundrum of the giraffe’s neck has been found in the writings of Charles Darwin’s work.
In an ancient population of giraffes there were individuals who just happened to have necks that were slightly longer than their counterparts. This allows them to reach higher branches, and as a result these deer are more successful in reproduction as they are able to subsist on wild food sources while the shorter deer do not. due to competition from many other species.
In addition, male giraffes compete for females by hitting each other with their necks, also known as “strangulation”. Giraffes with longer necks tend to win these matches, which means they are more likely to inherit their long neck genes.
There is also another theory. Deer necks help them regulate body temperature in the hot climates of Africa by increasing their body surface area through which internal heat can easily escape.
Over time, the environment will have natural selection. Organisms with more favorable survival characteristics will survive and produce generations with the same genetics as their ancestors, but with more enhancements.
Darwin’s Rebuttal Theory
In 1871, naturalist George Jackson Mivart published a book refuting the evolution of natural selection titled On the Genesis of Species. Like many other late 19th-century naturalists, Mivart accepted evolution but rejected the theory of natural selection.
According to Mivart, the giraffe itself is a perfect example of the ineffectiveness of natural selection. Suppose the giraffe’s long neck is an adaptation to reach the tall foliage during the droughts of Africa.
What has not been explained here is that if the drought environment allows for a longer neck, it is surprising that no other herbivore has adapted itself in the same way.
Besides, increasing the height of the body also comes with other challenges. Increased height means increased weight, increased weight means that giraffes will also require increased food intake. In extreme drought conditions, this process of natural selection has not necessarily brought the giraffe to its full advantage.
In 1872, Darwin took Mivart’s objection seriously and made it a point of doubt that needed further clarification.
Over the years, archaeologists have found a complete fossil record of an ancient species of giraffe called Bohlnia. This can be considered an “intermediate” species between the short-necked Samotherium and the modern giraffe.
Through the Bohlini species, scientists have guessed that the evolution from short to long neck began about 14 million years ago during the Miocene period.
Even so, the question “how did the ancestors of giraffes make their necks longer?” Further research is still needed to provide the most accurate answer.
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