An extinct human ancestor that cross-bred with us might have left its mark on our mental health, a new study reveals.
The Denisovans had a gene mutation that allowed them to adapt to the cold and when they bred with humans their genetic code was passed on and exists in some of us today.
The genetic variant, which affects zinc regulation, makes carriers more susceptible to conditions such as anorexia, obsessive-compulsive disorder, schizophrenia and depression.
Modern humans came ‘Out of Africa’ about 60,000 years ago and met populations of Denisovans in Asia. To this day, some people retain genetic variants of Denisovan origin in our genome.
A team led by the Institute of Evolutionary Biology (IBE) in Spain first noticed that the genetic mutation helped the transport of zinc in the cell.
So they worked with the Pompeu Fabra University (UPF), and by the UPF Department of Medicine and Life Sciences (MELIS) to get to the bottom of what it meant for people today.
Dr. Ana Roca-Umbert, first author of the study said they had ruled out the mutation coming from Neanderthals.
She said: “Through genomic analysis, we noted that the genetic variant observed came from our interbreeding with archaic humans in the past, possibly the Denisovans.”
Co-first author doctoral student Jorge Garcia-Calleja added: “Apparently, the change was beneficial and proved a selective advantage for humans.
“As a consequence, this variation in the SLC30A9 gene was selected and has reached current populations.”
Associate Professor Dr. Rubén Vicente, MELIS-UPF principal investigator, discovered that this genetic adaptation helped ancestral populations of sapiens to adapt to the cold.
He said: “We were contacted because the team had observed a change in an amino acid in a zinc transporter, which was very different between the populations of Africa and Asia today.
“From there, we started asking ourselves questions and looking for answers. The observed phenotype leads us to think of a possible adaptation to the cold.”
But zinc transport is also involved in nervous system excitability, and plays a role in people’s mental equilibrium and health.
The essential trace element for human health is an important messenger that transfers both information from the outside to the inside of cells and between different cellular compartments.
A lack of zinc causes growth, neurological and immune disorders.
The variant found in this zinc transporter, expressed in all tissues of the body, is associated with a greater predisposition to suffering from some psychiatric diseases.
These include anorexia nervosa, hyperactivity disorder, autism spectrum disorder, bipolar disorder, depression, obsessive-compulsive disorder, and schizophrenia.
Although the variant was established in Asia as a result of interbreeding between Denisovans and sapiens, it also spread to European and native American populations.
In fact, it is found in populations all over the planet, although, in the case of African populations, it is much less frequent.
Assistant Professor Dr. Elena Bosch, IBE principal investigator and co-leader of the study, published in the journal PLoS Genetics, said that it is probably the Denisovan genetic adaptation to have the greatest geographical scope discovered to date.
She added: “For example, a variant in the EPAS1 gene inherited from the Denisovans allows adapting to life at altitude, but is found only in Tibetans.
“However, in our case, the impact extends to all populations outside Africa.”
Dr. Vicente added: “In the future, expanding this study to animal models could shed light on this predisposition to suffering from mental illnesses.”
Produced in association with SWNS Talker
