In a significant discovery, scientists have found why modern humans develop brain disorders like autism or schizophrenia but our ancestor Neanderthals did not.

They have discovered the cellular equivalent of “on/off” switches that determine whether DNA is activated or not.

Hundreds of Neanderthals’ genes were turned “off” while the identical genes in today’s humans are turned “on”.

Alternatively, hundreds of other genes were turned “on” in Neanderthals but are “off” in people living today.

“The genes related to autism, as well as to schizophrenia and Alzheimer’s disease, were more likely to be “off” in Neanderthals than in modern humans,” said lead author Liram Carmel from Hebrew University of Jerusalem.

When dozens of brain-related genes became more active in today’s humans, it produced the harmful side effect of neurological illnesses, the study noted. The study was published in the journal Science.

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