Our ancestors were victims of a genetic mutation that suddenly and unexpectedly took something away from them: the tail.

Our ancestors were victims of a genetic mutation that suddenly and unexpectedly took something away from them: the tail.

The human body is full of defects, it is far from perfect, it is not even harmonious, because it is the product of a random and blind evolution, in the words of Richard Dawkins . Evolution is not about perfection, but about what Nobel Herb Simon called "satisficing" (satisfying enough), getting a result and settling for it.

Therefore, there are anatomical features of the human body that are useless or for almost nothing. Some of us have lost, others are still there. They are the so-called vestigial organs . Organs whose original function has been lost during evolution. Among those we have lost, one quite surprising is the tail.

The loss of the tail

Our ancestors had a tail, and this appendix lasted for millions of years. This in itself is surprising, as it is that we have lost it. Was it not effective at all? The point is that its loss was not gradual, but was lost unexpectedly due to a genetic mutation , as suggested by a new study carried out by a team of geneticists from New York University. This happened about 25 million years ago.

Primate genome sequencing projects have made it possible to identify causal links between genotypic and phenotypic changes, and allow the search for hominoid-specific genetic elements that control tail development .

The mutation is in a gene called TBXT, which encodes a transcription factor involved in embryonic development . TBXT was one of the first genes scientists discovered more than a century ago. Back then, many researchers searched for genes by bombarding animals, plants and microbes with X-rays, hoping that the mutations would create a visible change.

But while this discovery sheds light on how apes lost their tails, why they did is another matter entirely. "That is the next pending question: what would be the advantage?" "We must have had a clear benefit from losing our tail, either because of better locomotion or something else."

There must be some, considering that this mutation also carries a downside: increased development of spinal abnormalities similar to spina bifida (in fact, it is speculated that the relatively high rate of spina bifida among humans is a persistent relic of the loss of our tail).

All of which, underlines the words that one day the Nobel Prize winner François Jacob wrote, evolution looks like a handyman "who … often without knowing what he is going to produce … uses everything he finds around him, old cardboard, scraps of string, pieces of wood or metal, to create some kind of viable object… it’s a set of disparate pieces put together when and where the opportunity arose. "