NYU Scientists Find That Humans Lost Their Tails 25 Million Years Ago

Researchers from New York University Langone Health may have finally learned how early humans took a major step away from predecessor primates in the evolutionary process by no longer growing tails starting 25 million years ago, as reported by Alex Mitchell for the New York Post.

Looking at DNA samples of people, apes without tails, and monkeys, the scientists discovered that the latter is missing a piece of genetic code shared by the former two.

“Our study begins to explain how evolution removed our tails, a question that has intrigued me since I was young,” lead study author Dr. Bo Xia said.

Looking at DNA samples of people, apes without tails, and monkeys, the scientists discovered that the latter is missing a piece of genetic code shared by the former two.

This occurred not by mutation — the scientific term for changes within DNA — but instead by another genetic code “snippet” known as AluY, which was randomly inserted into early humans and non-tailed apes during prehistoric times, according to the study published as a cover story for the journal Nature.

The new gene, in a first-time discovery, was shown to affect tail lengths. When paired with another gene called TBXT, it formed two types of ribonucleic acid — critical to cellular structure — that produced tail loss in people and apes.

“This finding is remarkable because most human introns carry copies of repetitive, jumping DNAs without any effect on gene expression, but this particular AluY insertion did something as obvious as determine tail length,” said Dr. Jef Boeke, the Sol and Judith Bergstein Director of the Institute for Systems Genetics.

It is also believed that the major evolutionary schism had given rise to the coccyx — aka tailbone — in humans, gorillas, and chimpanzees.

Reporting for the Associated Press (AP), Christina Larson said there are many tantalizing theories about the change, including some that link being tailless to humans eventually learning to walk upright.

Rick Potts, who directs the Smithsonian Institution’s Human Origins Project and was not involved in the research, suggests being tailless may have been a first step toward some apes adopting a vertical body posture, even before they left the trees.

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