Scientists have solved the mystery of humanity losing its tails 25 million years ago

It all comes down to one piece of DNA

Our ancestors lost their tails about 25 million years ago, but scientists have recently figured out what caused the mutation that changed the course of primate history. Researchers from New York University have determined that it all comes down to one piece of DNA that is common to great apes but absent from apes.

The discovery involved the TBXT gene, which in some animals is associated with tail length, and when a small part was inserted The DNA, called AluY, tails have been lost, writes the Daily Mail.

Although the reason for the loss of the tail is unclear, some experts suggest it may be better suited to life on land than in trees.

Study author Bo Xia says, «Our research begins to explain how evolution robbed us of our tails, a question that has interested me since childhood.» Past work has shown that more than 100 genes have been linked to tail development in different species. vertebrate species, and the study authors hypothesized that the loss of the tail occurred due to changes in the DNA code of one or more of them.

AluY fragments are also called «jumping genes» or «transposable elements» because they can be moved and inserted repeatedly and randomly into human code.

The elements are also responsible for the regulation of tissue-specific genes and can change the way a gene is expressed.

In a new study, researchers identified two jumping genes in TBXT that are found in great apes, leading to the hypothesis that AluY accidentally inserted itself into the code tens of millions of years ago.

To solve the mystery, researchers injected jumping genes into 63 mice, finding that the offspring had tails that were either shorter or completely absent.

According to the researchers, any benefit associated with tail loss was likely significant because it could occur despite the costs.

Specifically, the researcher found a small uptick in neural tube defects in mice with the study insertion in TBXT gene. Moreover, the AluY insertion remained at the same location in the TBXT gene in humans and monkeys, resulting in two forms of TBXT RNA. And one of the shapes likely contributed to the loss of the tail.

Professor Jeff Boeke from NYU Langone Health comments: «This discovery is remarkable because most human introns carry copies of repetitive, jumping DNA without any effect on gene expression, but this particular AluY insertion did something as obvious as determining tail length.» .

Gorillas, chimpanzees and humans are believed to have lost their tails when they split from Old World monkeys, researchers say. After this evolutionary split, the group of great apes that includes modern humans evolved to have fewer tail vertebrae, resulting in the coccyx, or coccyx bone.

Famous naturalist Charles Darwin discovered changes in the anatomy of humans and our ancestors in in his 19th-century book The Descent of Man, but could not be sure that the coccyx was an ancient tail.

“I believe that the coccyx provides attachment to certain muscles, but I have no doubt that it is a vestigial tail.” , wrote Darwin.