Slow human molecular clock
2006/04/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria
In the human species, the distance between one generation and the next is large, about 20 years old. Other primates reach sexual maturity before humans and therefore have less room between generations. For example, the chimpanzee has a 15-year difference between one generation and the next.
The great intergenerational distance is a characteristic feature of the human species. Well, according to an article published in the scientific journal PNAS, this feature is relatively new in human evolution.
The authors of the article compared much of the human genome with that of the chimpanzee and with other primates such as baboon, gorilla and orangutan. Specifically, they have looked at the molecular clock. The molecular clock indicates the rhythm at which mutations occur in the genome. Since most mutations occur in the formation of eggs and sperm, the greater the intergenerational distance, the slower the molecular clock.
Scientists have seen that the human molecular clock is 11% slower than that of the gorilla. But chimpanzee is also 8% slower than gorilla. That is, although the intergenerational interval is quite uneven between man and chimpanzee, the difference is not so evident as to the speed of the molecular clock.
Hence it follows that the existence of such a large generational gap has recently manifested itself in evolution. Researchers estimate that it appeared about a million years ago.
The calculation coincides with the theories of paleoanthropologists. In fact, the remains of a 1.5 million year old Homo erectus were discovered in Kenya and, after analyzing their tooth, they concluded that the species reached sexual maturity before the current human being, in a period similar to the chimpanzee. However, in Spain the same study was carried out with a Homo sapiens of 800,000 years ago and they have seen that it needed the same time as the current one.
