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American molecular biologists have discovered that the common ancestors of humans and apes lost their tails due to the joining of a fragment of self-replicating DNA to one of the regions of the gene TBX Which controls tail growth within the mammalian embryo.
It was stated in a study published by researchers in the journal Nature American: “We have discovered evidence that insertion of a self-replicating DNA section into the regulatory part of a gene TXBT It caused human ancestors to lose their tails, but implanting this part of the gene in the DNA of mice led to them losing their tails and also made them vulnerable.”
This conclusion was reached by a group of American biologists led by Professor Itai Yanai at New York University while studying the extent to which the structure of 140 genes supposedly related to tail formation in mammals differs in the genomes of humans and apes.
In total, scientists were able to identify nine mutations in these genes, which are unique to primates and humans, and greatly affect their functions. Only one of them affected the tail growth system and did not cause disturbances in the development of other parts of the body.
The researchers compared the genomes of six hominin species, including humans, and 15 species of tailed monkeys to identify key differences between the groups. Once they identified an important mutation, they tested their theory by using a gene-editing tool to change the same spot in mouse embryos. Those mice were born without… “tails”.
Did the lack of tails help hominin ancestors – and eventually humans – survive, or was it just a chance mutation in a population that thrived for other reasons, the researchers wondered?
“This may be a random coincidence, but it brought a significant evolutionary advantage,” said Miriam Kunkel, an evolutionary geneticist at Clemson University.
Rick Potts, who directs the Smithsonian Institution’s Human Origins Project, noted that the lack of a tail may have been a first step towards some hominins adopting an upright body posture, even before they left the bush.
“Losing our tails was clearly a major shift,” said Itai Yanai, a biologist at New York University and co-author of the study.
He added that the only way to know for sure the reason may be to invent a time machine.
Source: Agencies