Baboons, commonly found in East Africa, are highly adaptable and often approach humans. Image courtesy of Flickr.
Of the vast number of differences between humans and our closest primate relatives, perhaps the most obvious is our lack of a tail—the cause of which was a mystery until recently.
Having a tail separates monkeys from apes like us. Recently, a team of researchers led by Harvard research fellow Bo Xia set out to find the cause for this evolutionary split, which occurred between twenty and twenty-five million years ago. The team was able to pinpoint the specific gene in primates responsible for our lack of a fifth appendage: the TBXT gene, which dictates tail length. Using the CRISPR/Cas9 system, a technology that allows scientists to modify the genes of living organisms, the team replicated the mutation in mouse embryos in their lab. The result? Many mice had markedly smaller tails, with some lacking any tail structure at all.
The remaining question for the researchers is why this change came about. Losing our tails played a part in our eventual bipedalism as we stopped living in the trees. As we walked away from our primate cousins, we walked toward a new tailless era catalyzed by a fundamental change in the TBXT gene.