Scientists have solved the mystery of tail loss in humans: the 1927 work of Ukrainian researcher and a cab injury helped

A genetic mutation that occurred 25 million years ago caused great apes to lose their tails. We are talking about changes in the TBXT gene.

The theory of tail loss was published by researchers led by geneticist Bo Xia in the journal Nature. Interestingly, Xia's research was prompted by an injury sustained during a cab ride, and the work of Ukrainian scientist Nadiia Dobrovolska-Zavadska helped solve the mystery.

Xia admits that since childhood he has been interested in the question of where and why his tail disappeared. However, he decided to seriously study this question a few years ago when he was recovering from an injury to his coccyx, the bone in the lower back from which monkeys grow their tails.

Now Xia and his colleagues have an answer. The researchers have identified a genetic change shared by humans and other apes that may have caused their ancestors to lose their tails about 25 million years ago.

Unlike most apes, humans do not have tails. However, they still have the coccyx, which is the remnant of the vertebrae that form the tail in other animals. After suffering an injury to his coccyx, Xia decided to solve the mystery of the disappearance of tails.

Luckily, he came across a 1927 study in which Ukrainian scientist Nadiia Dobrovolska-Zavadska described a species of short-tailed laboratory mouse. The scientist then suggested that the mouse had a mutation in a gene called T. This gene is the equivalent of the human gene TBXT.

Xia's further research revealed that humans and other great apes carry a DNA insertion in TBXT that is not present in other tailed primates, such as monkeys.

Further investigation revealed that the monkey "insertion" could lead to a shortened form of the protein that encodes TBXT. The shortening, according to the scientists, occurred after the gene was transcribed into messenger RNA, and when several segments of the gene transcript encoding the protein were joined together.

However, the problem was to prove this not only on paper. The first experiments with a genetic insert transplanted into the mouse genome did not yield the desired result, as the experimental mice had normal tails.

Then the researchers created mice with a different insertion in the T gene. By chance, this led to the gene being incorrectly spliced, just as it happens in humans. Mice with this insertion were born with short or completely absent tails.

In addition to this change in DNA, other variations in genetic changes that are unique to great apes have also been identified and may also play a role in tail loss.

In addition to great apes, there are other primates that do not have tails. According to Xia, this suggests that there are multiple evolutionary pathways for tail loss.

"There are probably several ways to lose a tail during development. Our ancestors chose this path," Xia said.

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