Why Homo sapiens sapiens lost its tail

Question:

What is the difference between great apes and other monkeys?

Answer:

Monkeys - we usually know them from the zoo: baboons, gorillas, monkeys, chimpanzees, spider monkeys, a total of around 350 species. They are summarized in the mammalian order of primates and are often referred to as our cousins. Some of them are even called "great apes". Why? And what makes them different from the other monkeys?

First of all, we should clarify the question of who is one of the great apes living today. The great apes in the broader sense comprise two families: the small and the great great apes. Small apes are the family of gibbons that live in Southeast Asia. The great apes include the chimpanzees and gorillas from Africa, the orangutans from Southeast Asia and we, homo sapiens, the human being.

Why are humans, chimpanzees, gorillas and orangutans all grouped together in a family? Initially, such a classification was made on the basis of physical characteristics that distinguish this group from others. The most striking feature: great apes do not have a tail. They are usually larger and heavier than other monkeys and hold more erect. The chest is wider and the shoulder joint set further back allows the upper arms to move freely. In contrast to the other monkeys, the great apes' arms are longer than their legs. Humans are an exception in this case. An essential feature is that the brain of the great apes is significantly larger in relation to the body than that of the other apes. In order to develop such a complex brain, pregnancy and adolescence are significantly extended to adulthood.

In addition to these external characteristics of kinship, the development of molecular biological methods has recently made it possible to analyze kinship on the basis of genetic similarities between species. In addition, due to the relatively constant mutation rates of certain genes, a “molecular clock” can be set up. With the help of this “clock”, the approximate point in time at which the last common ancestor of two species lived can be determined.

The original form of all primates probably lived around 80 to 90 million years ago, i.e. at the time of the dinosaurs. In the course of evolution, more and more primate species emerged. Many became extinct, while others split up into new species. About 25 million years ago, the great apes split off from the other apes. The kinship relationships within the great apes living today are as follows: The orangutan split off from the other great apes around 15 million years ago and is consequently the ape least related to humans. The gorillas split off about 9 million years ago. Our direct and closest relatives are the chimpanzees, with whom we share 98.4% of our genes according to molecular biological studies. The last common ancestor of humans and chimpanzees lived about 6 million years ago.

Incidentally, humans are the only great apes that are not threatened with extinction.