Crossbreeding of Humans, Now-Extinct Species Denisovans Contributes to Mental Health Issues [Study]

DNA from now-extinct species Denisovans can be traced in modern humans. The crossbreeding between humans and Denisovans reportedly contributed to mental health issues like depression.

Humans, Denisovans Crossbreeding and Mental Health Issues

A recent study asserted that having sex with a now-extinct subspecies that humans met in Asia approximately 60,000 years ago could be the cause of depression. Scientists have found a DNA mutation associated with human-Denisovan intermarriage that they believe impacts human mood.

Individuals who carry the variation have reduced zinc levels in their bodies, a vitamin that is increasingly linked to happiness and mood, according to research.

SLC30A9, which originated in Asia and has now expanded to populations in Europe and North America, is the most widely distributed Denisovan gene found so far, according to scientists. It has only become possible for scientists to trace the DNA of modern humans back to our ancient ancestors recently, thanks to advancements in genome sequencing.

Numerous times, the various branches of the human family tree have interbred and exchanged genes, a process known as introgression.

Elena Bosch, evolutionary biologist and the study's co-leader and main investigator for IBE, and her colleagues discovered an adaptive variant in modern human populations in a section of our genome that remarkably resembles the genome of an extinct ancestor group known as the Denisovans.

According to Bosch, they found out that the mutation had implications for the transport of zinc within the cell. When Neanderthal ancestry was investigated, researchers discovered that the group lacked the mutation.

MELIS-UPF chief investigator Rubén Vicente then joined the team to examine the mobility of intracellular zinc. Bosh reached out to Vicente after her team noticed a shift in an amino acid in a zinc transporter that was significantly different between the populations of Asia and Africa at the time. Per Vicente, it sparked a question for themselves, and they decided to find the answer.

His lab discovered that the reported mutation induces a shift in the cell's zinc balance, which drives a modification in metabolism. As a result, the mutation enabled Denisovans to survive in the harsh, frigid climate that formerly decimated Asia.

Zinc transport contributes to nervous system excitability and maintains mental stability and human wellness. The group notes that a variation in this zinc transporter, which is expressed in every bodily tissue, is linked to a higher risk of developing certain mental illnesses.

These include obsessive-compulsive disorder, bipolar disorder, autistic spectrum disorder, anorexia nervosa, hyperactivity disorder, depression, and schizophrenia.

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Who Are the Denisovans?

According to gene analysis, Denisovans and Neanderthals are relatives, and the two diverged between 400,000 and 500,000 years ago. Studies on Denisovan DNA in contemporary Papua New Guineans indicate that approximately 46,000 years ago, the two populations interbred.

Furthermore, another interbreeding event is proposed to have occurred approximately 30,000 years ago and maybe as recently as 15,000 years ago. Although there is disagreement about the evidence supporting the later date, it appears likely that Denisovans survived at least 30,000 years ago.