(TMU) — The mystery of human evolution is one of the most vexing questions in science. A stunning physiological relic recently discovered by biologists may shed light on the transition from reptiles to mammals. Scientists believe they have identified a 250 million-year-old lizard-like muscle that very young pre-natal babies develop in their hands and then lose before birth.
The discovery was made after studying 3D medical scans of 15 embryos and fetuses ranging from seven to 13 weeks gestation. Biologists believe the extra dorsometacarpales may help explain humans’ thumb movement, which was an important part of our evolution in the distant past.
“We have a lot of muscles going to the thumb, very precise thumb movements, but we lost a lot of muscles that are going to the other digits.
In our evolution, we do not need them so much.
Why are they there? Probably, we cannot just say in evolution, ‘Look, I will delete from scratch, from day zero, the muscle going to digits two, three, four, five and I will just keep the one going to the thumb.’
Probably it is not so easy. Probably you have to form this layer of this muscle and then it disappears on the other digits but persists on the thumbs.”
The human body contains other anomalous developmental relics, such as redundant appendix (though there is currently a debate about the true function of this organ), wisdom teeth and coccyx, but Dr. Diogo believes the reptilian leftover is significantly more significant.
“These muscles were lost 250 million years ago,” he said.
“No adult mammal, no rat, no dog has those muscles. It’s impressive. It was really a long time ago.
It used to be that we had more understanding of the early development of fishes, frogs, chicken and mice than in our own species but these new techniques allow us to see human development in much greater detail.”
The finding raises questions though, such as why we lose such features, which Diogo says allow other mammals to climb with their feet and which could make us “super-humans.”
Anthropologist Dr Sergio Almécija says we must look for other missing parts.
“The important question for me now is, ‘What else are we missing? What will we find when all the human body is inspected at this detail during its development?
What is causing certain structure to disappear and then to appear again? We can now see how it happens but what about the why?”
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