in our ancient times homo sapiens Our ancestors first left Africa for Eurasia about 60,000 years ago, where they met and interbred with some of the other human species who lived in their new, cold homeland. These include the now extinct Denisovans, who may have given modern humans genes that helped them adapt to cold temperatures and increased susceptibility to schizophrenia and other mental illnesses. there is.
Our encounters with other archaic human species have left an indelible mark on the genomes of modern humans around the world, with a small portion of our DNA inherited directly from both Neanderthals and Denisovans. I am. By examining the genetic makeup of 26 current populations and cross-referencing them with the genomes of their extinct cousins, the authors of a new study found one of the most widespread traces of Denisovan DNA in modern humans. did.
According to researchers’ analysis, current populations in every region except Africa contain a particular variant of a gene called . SLC30A9, probably as a direct result of interbreeding with Denisovans in the distant past. The gene itself encodes a protein called ZnT9, which transports zinc across cell membranes.
This variant does not appear in the Neanderthal genome, thus excluding this species as the origin of the gene. At the same time, researchers found that modern African genomes typically contain older variants. SLC30A9 It predates the introduction of the Denisovan allele.
Geographic distribution of Denisova SLC30A9 gene variants.
Image credits: Jorge Garcia and Elena Bosch
“Through genome analysis, we found that the observed genetic variation originates from interbreeding with archaic humans in the past, most likely Denisovans,” study author Ana Roca-Umberto explained in the paper. statement. “Apparently, this variation has proven to be beneficial and a selective advantage for humans. SLC30A9 The genes were selected and arrived at the current population,” added co-author Jorge García Calleja.
To find out how the Denisova mutant affects physiology, the researchers introduced this DNA into human fetal kidney cells and changed the amount of zinc that enters key cell structures such as mitochondria and the endoplasmic reticulum. I focused on making it happen. This led to changes in mitochondrial metabolism, preventing ‘zinc overload’ and resulting in an overall ‘gain of function’.
Based on this observation, the study authors suspect that genetic variation inherited from Denisovans may have contributed to antiquity. homo sapiens Better adaptation to cold weather. But zinc imbalances can cause neurological disorders, so the DNA our ancestors acquired when interbreeding with other human species may also have left an imprint on our mental health. .
In support of this negative side effect, the study authors wrote that the widespread Denisova variant is “known to be associated with increased susceptibility to several neuropsychiatric disorders.” These include conditions such as schizophrenia, bipolar disorder, depression, and anorexia nervosa.
Incorporating their various findings into theories about Denisovan introductions SLC30A9 The researchers speculate that “adaptation to cold weather may have driven this selection event outside of Africa, while also influencing the predisposition to neuropsychiatric disorders in modern humans.” There is.
The research will be published in a journal PLOS Genetics.
