99.84% of our genes are the same as Neanderthals. But thanks to variations, this “cousin” would never have developed diseases like autism or Alzheimer’s.
Could Alzheimer’s disease be explained more by evolution than by way of life? This is one of the many questions raised by a study published on April 21 in Science. An international team (Max-Planck Institute, Hebrew University of Jerusalem, University of Oviedo) compared genetic variations between modern man and several now extinct hominid species (including Neanderthals and hominids). by Denisova). The results suggest that some genes associated with the nervous and cardiovascular systems vary dramatically.
A genome that is 99.84% similar
This epigenetic study could explain the recent occurrence of certain diseases. This field is interested in slight variations in genes which, without altering their structure, modulate their activity. Thanks to this, the researchers were able to suggest that, had Neanderthals lived until today, he may never have developed Alzheimer’s disease. To achieve this, they put the complete genome of our extinct “cousin” in parallel with that of modern man. They are 99.84% genetically similar. For comparison, the genome of chimpanzees – our closest living “cousins” – is 98.8% similar to ours. Studies have already made it possible to determine that Neanderthals would have “bequeathed” to Europeans a good part of their fat.
Variations on the nervous system
What causes the real differences between species is epigenetics. With almost the same basic genome, the Neanderthals and modern humans would not have developed the same anatomy. Certain variations “affect genes associated with bone development, and may explain the variations between the skeleton of ancient species and modern humans,” explains Dr Mario Fernandez-Fraga of the University of Oviedo (Spain). Others relate to genes associated with the nervous and cardiovascular systems or brain function.
These variations are crucial for research. In some cases, genes that were inactive in Neanderthals were indeed active in modern humans. This is the case with those linked to autism, schizophrenia or Alzheimer’s disease. This raises the question of evolution in the face of genetic predispositions. “One can wonder if these diseases, so frequent in the current society, reflect a predisposition inherent in our species or if, on the contrary, it is a consequence of our way of life and of the environment in which we evolve”, analysis Jose Riancho, from the University of Oviedo. The proximity to Neanderthals is not all good: last January, a study in Science pointed out that this ancestry would be at the origin of autoimmune diseases (Crohn’s disease, lupus, liver diseases) or even type 2 diabetes … even smoking!
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