Change in gene code may explain how human ancestors lost tails. Mechanism behind change may reveal new role for parts of the genetic code.

Hey there! Ever wondered why humans don’t have tails like monkeys? Well, researchers at NYU Grossman School of Medicine may have figured it out! They found that a genetic change in our ancient ancestors might be the reason behind it. This discovery, published as the cover story in the journal Nature, compared the DNA of tail-less apes and humans with that of tailed monkeys. They discovered a DNA insertion shared by apes and humans but missing in monkeys.

To dive deeper into this, the research team engineered mice to see how this insertion, found in a gene called TBXT, affected their tails. Surprisingly, they found a variety of tail effects, even some mice born without tails! Dr. Bo Xia, one of the study authors, expressed excitement about unraveling this evolutionary mystery that has intrigued him since childhood.

Previous research had linked over 100 genes to tail development in various vertebrates, leading the authors to hypothesize that changes in these genes’ DNA code played a role in tail loss. However, they were astonished to find that the differences in tails didn’t stem from mutations in TBXT, but rather from the insertion of a DNA snippet called AluY into the gene’s regulatory code in the ancestors of apes and humans.

This discovery sheds light on how genetic instructions are converted into proteins and how alternative splicing can influence traits like tail length. Despite not directly altering the protein-coding sequence, this insertion influenced alternative splicing, resulting in various tail lengths.

The researchers speculate that this genetic change, which occurred about 25 million years ago, might have provided an advantage for life on the ground compared to trees. However, it’s also associated with a small increase in neural tube defects in mice, hinting at a possible evolutionary trade-off.

In addition to providing insights into our evolutionary history, this study showcases the intricate complexity of the human genome and the role of “jumping genes” in shaping our traits. It’s a fascinating glimpse into how tiny genetic changes can have profound effects on species over millions of years.

The study, led by Drs. Bo Xia, Jef D. Boeke, and Itai Yanai, involved a collaborative effort from several researchers at NYU Langone Health and was supported by various grants and funding sources.

Journal Reference:

Bo Xia, Weimin Zhang, Guisheng Zhao, Xinru Zhang, Jiangshan Bai, Ran Brosh, Aleksandra Wudzinska, Emily Huang, Hannah Ashe, Gwen Ellis, Maayan Pour, Yu Zhao, Camila Coelho, Yinan Zhu, Alexander Miller, Jeremy S. Dasen, Matthew T. Maurano, Sang Y. Kim, Jef D. Boeke, Itai Yanai. On the genetic basis of tail-loss evolution in humans and apes. Nature, 2024; 626 (8001): 1042 DOI: 10.1038/s41586-024-07095-8

Reference Site:

Science daily News Article.

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