A genetic mutation would be behind it. In a new study, researchers theorized that the change was mediated by the addition of a short segment of DNA
It is known that, millions of years ago, humans had tails. Scholars have always said that the loss of this part was due to evolution and loss of use of the limb. A new study by researchers in New York, however, has tried to go deeper into the issue and it has been theorized that at the base there would be a genetic mutation. The change would be mediated by the addition of a short segment of DNA, known as the Alu element, and would be the reason why humans and hominids such as chimpanzees, bonobos and Bornean orangutans do not have tails, while other apes do.
Research into why humans no longer have tails
The study was carried out by Bo Xia, a graduate student in stem cell biology at NYU Grossman School of Medicine. During the analysis, the development of the embryo was observed with a focus on which genes were turned on and which were turned off at different points during growth inside the uterus. At the same time, tail development in other animals was also analyzed, then comparing DNA from tailless monkeys to that of monkeys with tails.
Building on previous findings that identified more than 30 genes responsible for tail development in various animals, including Manx cats that are known to have no tail or only a small bump caused by a genetic mutation, Xia theorized that similar variation may have happened to our ancestors.
The discovery about the genetic mutation
From comparing DNA from monkeys, Xia identified a mutation in the TBXT gene evident in humans, but not in primates with tails. To test his theory, Xia and his team genetically modified mouse embryos to see what would happen and found that adding the TBXT gene resulted in some mice being born without tails while others developed short, stubby tails. The result led Xia and his colleagues to hypothesize that 20 million years ago, a random genetic mutation in an ape caused it to develop a shortened tail or no tail at all. The ancient ape born with the mutation then passed the trait on to its offspring and several genealogies up to humans.
Regarding theories of evolution, there is also a study that believes the evolution of Homo Sapiens is still ongoing, while research has looked at what effects climate has on human body size.
Stefania Bernardini