Since the theory of evolution was first formed in the 19th century, scientists have believed that humans descended from primates and now a new study has revealed why both humans and apes don’t have tails, unlike primate cousins such as monkeys.
It is thought that ancestors of both apes and humans had tails until around 25 million years ago when one ancestor genetically diverged from monkeys and lost its tail. The exact DNA mutation that led to this dramatic evolution had remained unknown until the arrival of a new scientific study that was published in the journal Nature on February 28.
The DNA mutation that may have caused humanity’s ancestors to lose their tails
The length of an animal’s tail is related to a gene within DNA called TBTX according to Live Science.
In the aforementioned study, scientists found that two so-called Alu elements that are found in the TBXT gene in great apes were not found in monkeys, their primate relatives.
Alu elements are DNA sequences that have the ability to produce pieces of RNA, a cousin of DNA, that is able to ‘jump’ generations and can cause changes in a species’ genome by modifying the structure of the protein created by a strand of DNA.
The study hypothesized that these Alu elements could have led to hominoids such as humans and apes evolving to lose their tails.
In order to prove their theory, researchers conducted an experiment by inserting these ‘jumping genes’ into a group of mice and found that those with the Alu elements in their DNA lost their tails or had shorter tails than those without these Alu elements.
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Losing tails is thought to have led to humans walking on two legs
A review carried out in 2015 hypothesized that the loss of tails in hominoid evolution led to humans becoming bipedal.
Humans are the only mammals to walk exclusively on two legs and this new study is supposedly “the only paper that has ever put together a plausible scenario for how it [humans becoming bipedal] happened,” according to Itai Yanai, scientific director of the Applied Bioinformatics Laboratories at NYU Langone Health and a senior author of the study who spoke with Live Science.
“We’re now walking on two feet. And we evolved a big brain and wield technology,” Yanai said. “All from just a selfish element jumping into the intron [part of DNA structure] of a gene. It’s astounding to me.”
Fellow researcher Jef Boeke, director of the Institute for Systems Genetics at NYU Langone Health and a senior author of the study, believed that other mutations in our traits caused by Alu elements could exist, telling Live Science, “I think there’s going to be more of them out there.”
