Modern humans carry a genetic legacy from the Denisovans, an archaic human species that interbred with our ancestors tens of thousands of years ago. This genetic inheritance has raised intriguing questions about its potential impact on our mental health, specifically in relation to conditions such as depression, according to a recent study conducted by researchers from Spain.
The study builds on previous research that pinpointed a variant of the SLC30A9 gene as having evolved through positive selection, particularly in East Asian populations. SLC30A9 is responsible for regulating and transporting zinc across cell membranes, a crucial function for healthy growth, as well as the proper operation of our neurological and immune systems.
This specific genetic adaptation alters the regulation of zinc, but its origin remained a mystery until now. A comparison with the Denisovan genome revealed a match for the same mutation in East Asian populations, while no such match was found in Neanderthal populations.
“Through genomic analysis, we noted that the genetic variant observed came from our interbreeding with archaic humans in the past, possibly the Denisovans,” explained evolutionary biologist Ana Roca-Umbert from UPF.
Laboratory experiments conducted by the research team demonstrated that this genetic variation influenced how certain cellular structures, including mitochondria, managed zinc. This alteration may potentially affect metabolism.
Scientists have long suspected that there must be some selective advantage to preserving the SLC30A9 gene, but the nature of these advantages remained elusive. It now appears that the Denisovan variant may have provided better protection against cold climates.
“Apparently, the change was beneficial and proved a selective advantage for humans,” noted evolutionary biologist Jorge Garcia-Calleja, also from UPF. “As a consequence, this variation in the SLC30A9 gene was selected and has reached current populations.”
This genetic link with the past is one of the most widespread and significant discoveries to date. However, researchers are eager to delve deeper into how these genetic legacies continue to evolve and influence our well-being.
The same SLC30A9 variation has previously been associated with an increased risk of depression and other mental disorders. The likely connection lies in the gene’s role in regulating zinc, which is essential in managing the excitability of the nervous system and has known implications for mental health. Researchers plan to further investigate this relationship.
“In the future, expanding this study to animal models could shed light on this predisposition to suffering from mental illnesses,” said molecular biologist Rubén Vicente from UPF. The potential implications of our ancient genetic heritage on our mental health provide a fascinating avenue for ongoing research.
