Scientists have studied the oldest living brain discovered to date. They then discovered “a common signature” to the manufacture of brains in evolution.
What does a 525 million year old brain look like? With such antiquity, it is not a question of a human brain, but rather of another animal existing at that remote time. For works published in Science, November 24, 2022, four paleontologists looked at the remains of a lobopodian. This animal, totally extinct today, was an inverterbred living more than 500 million years ago in the seabed.
A recently rediscovered fossil has well-preserved parts of what was… his brain. Oldest listed to date. “ Until very recently, it was commonly believed that brains did not fossilize and therefore one would not expect to find a fossil with a preserved brain. “, details Frank Hirth, one of the authors of the study. ” This animal is so small that one would not even dare to look at it in the hope of finding a brain in it. »
The size of the specimen is only 1.5 centimeters. In fact, the study was perilous: the use of radiography was impossible. The paleontologists therefore mobilized several high-resolution shots, which they superimposed to filter all the wavelengths. Thus, the scientists produced a map of this 525 million year old brain… not without surprises.
“A common genetic base plan”
The scientists made a comparison between this specimen and the terrestrial arthropods of our time (spiders, centipedes, etc.). The result took them by surprise: it seems that the brain-nervous system structure has remained more or less the same for 525 million years. The same pattern repeated itself between the Lower Cambrian and the present day. Hypotheses assumed that the first species of this genus were structurally different over time.
” We have identified a signature common to all brains and their mode of formation », rejoiced Frank Hirth. ” We realized that each domain of the brain, and its corresponding characteristics, are specified by the same combination of genes, regardless of the species studied. This helps identify a common genetic blueprint for building a brain. »
It remains to be seen whether this same continuity would be applicable to other animal genera. In any case, this offers a more complete look at certain mechanics of evolution, the workings of which are played out on the scale of hundreds of millions of years.
For Frank Hirth, moreover, this discovery is to be put into perspective with the current human disturbances of ecosystems: “ At a time when major geological and climatic events were reshaping the planet, simple marine animals like Cardiodictyon gave rise to the world’s most diverse group of organisms — euarthropods — which eventually spread to every emergent habitat on Earth. , but which are now threatened by our own ephemeral species. »