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1 year ago
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Humans having sex with a now-extinct subspecies they met in Asia some 60,000 years ago could be the reason you have depression, a new study has claimed.
Researchers discovered a gene variant linked to the crossbreeding of humans and Denisovans which they believe affects our mood.
Those with the variant have lower levels of zinc in the body - a nutrient which studies increasingly show is associated with mood and happiness.
Scientists said SLC30A9 is the most widespread Denisovan gene discovered to date - starting in Asia and has spread to European and Native American populations.
Only recently with the advances in genomic sequencing has it been possible for scientists to trace modern human's DNA back to our ancient ancestors.
Researchers led by Barcelona's Pompeu Fabra University discovered a gene variant dwindling from the intermingling with an archaic human, Denisovans, involved in zinc regulation that releases lower amounts
The the mutation helped Denisovans cope with the cold, hostile climate that once ravaged Asia
The different branches of the human family tree have interbred and swapped genes — a processes known as 'introgression' — on numerous occasions.
Elena Bosch, IBE principal investigator and co-leader of the study, and her team identified an adaptive variant among current human populations in a region of our genome that bears remarkable similarity to the genome of an extinct ancestral population: the Denisovans.
'We discovered that this mutation surely had implications for the transport of zinc within the cell,' said Bosch.
Researchers did look into Neanderthal heritage but found the population was absent of the mutation.
Rubén Vicente, MELIS-UPF principal investigator, then joined the team to analyze intracellular zinc's movement.
'Elena contacted me because her 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, Vicente said.
'From there, we started asking ourselves questions and looking for answers.'
His laboratory identified that the observed variant causes a new zinc balance within the cell, promoting a change in metabolism.
This led them to find that the mutation helped Denisovans cope with the cold, hostile climate that once ravaged Asia.
Zinc transport is also involved in nervous system excitability and plays a role in people’s mental equilibrium and health.
The team points out that the variant found in this zinc transporter, which is 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.
The Denisovans are thought to have been a sister species of the Neanderthals, who lived in western Asia and Europe at around the same time.
The two species appear to have separated from a common ancestor around 200,000 years ago, while they split from the modern human Homo sapien lineage around 600,000 years ago.
Bone and ivory beads found in the Denisova Cave were discovered in the same sediment layers as the Denisovan fossils, leading to suggestions they had sophisticated tools and jewellery.
WHO WERE THE DENISOVANS?
The Denisovans are an extinct species of human that appear to have lived in Siberia and even down as far as southeast Asia.
Although remains of these mysterious early humans have only been discovered at one site - the Denisova Cave in the Altai Mountains in Siberia, DNA analysis has shown they were widespread.
DNA from these early humans has been found in the genomes of modern humans over a wide area of Asia, suggesting they once covered a vast range.
DNA analysis of a fragment of pinky finger bone in 2010, (pictured) which belonged to a young girl, revealed the Denisovans were a species related to, but different from, Neanderthals.
They are thought to have been a sister species of the Neanderthals, who lived in western Asia and Europe at around the same time.
The two species appear to have separated from a common ancestor around 200,000 years ago, while they split from the modern human Homo sapien lineage around 600,000 years ago.
Bone and ivory beads found in the Denisova Cave were discovered in the same sediment layers as the Denisovan fossils, leading to suggestions they had sophisticated tools and jewellery.
DNA analysis of a fragment of a fifth digit finger bone in 2010, which belonged to a young girl, revealed they were a species related to, but different from, Neanderthals.
Later genetic studies suggested that the ancient human species split away from the Neanderthals sometime between 470,000 and 190,000 years ago.
Anthropologists have since puzzled over whether the cave had been a temporary shelter for a group of these Denisovans or it had formed a more permanent settlement.
DNA from molar teeth belonging to two other individuals, one adult male and one young female, showed they died in the cave at least 65,000 years earlier.
Other tests have suggested the tooth of the young female could be as old as 170,000 years.
A third molar is thought to have belonged to an adult male who died around 7,500 years before the girl whose pinky was discovered.
