New York University researchers have a theory on how humans lost their tails

NYU researchers have a theory on how humans lost their tails. (Representational)

Researchers from New York University Langone Health have peeled back the layers of time, uncovering the pivotal moment in human evolution when our ancestors bid farewell to tails. The study, led by the Dr. Bo Xia, unravels the intricate genetic dance that occurred 25 million years ago, reshaping the course of human evolution.

Delving into DNA samples from humans, tailless apes, and monkeys, the scientists unearthed a genetic code "snippet" named AluY, rewriting the narrative of our evolutionary journey.

The research, chronicled in the journal "Nature," marks a significant leap in understanding the disappearance of tails among early humans and non-tailed apes. Dr. Xia, the lead study author, expressed the personal intrigue that fuelled this scientific quest, stating to New York Post, "Our study begins to explain how evolution removed our tails, a question that has intrigued me since I was young."

The genetic investigation revealed a commonality in DNA between tailless apes and humans, distinguishing them from monkeys. Contrary to the conventional understanding of genetic mutation, this transformation wasn't driven by mutations but rather by the insertion of the AluY genetic code snippet.

Dr. Jef Boeke, the Sol and Judith Bergstein Director of the Institute for Systems Genetics, emphasized the exceptional nature of this discovery, stating, "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 determining tail length."

The newfound gene, when combined with another named TBXT, gave rise to two distinct types of ribonucleic acid critical to cellular structure. This development elucidates how tail loss in humans and apes was orchestrated at a genetic level.

The study also posits that the evolutionary schism leading to tail loss may have played a role in the development of the coccyx, or tailbone, in humans, gorillas, and chimpanzees.

However, the lingering mystery lies in understanding why the ancient evolutionary forces dictated that tail loss was the optimal path for survival. Dr. Itai Yanai, a study author, hinted at future experiments to explore the hypothesis that the loss of tails in humans might have been an ancient evolutionary trade-off, potentially contributing to neural tube birth defects.

Experiments with mice even suggested a correlation between tail loss and an increased incidence of neural tube defects, mirroring conditions like spina bifida in humans.