New research suggests that sadness could result from mating with an extinct Asian subspecies that encountered humans around 60,000 years ago.
Scientists believe a DNA mutation associated with human and Denisovan hybrid ancestry influences human emotional states.
Only now, with the advent of genomic sequencing, can scientists use current humans’ DNA to reconstruct our distant genetic ancestry.
Numerous gene-swapping instances (“introgression”) have occurred between distinct branches of the human family tree.
Principal investigator and co-leader of the study, Elena Bosch of the Institute for Biological Evolution (IBE), and her colleagues found an adaptive variant in modern human populations in a region of our genome that shows striking similarities to the genome of an extinct ancestral community, the Denisovans.
They found that this mutation unquestionably affected zinc transport within the cell.
There was an investigation for Neanderthal ancestry, but no evidence of the mutation was identified in the sample population.
The primary investigator of MELIS-UPF, Rubén Vicente, later joined the group to study the mobility of zinc throughout the cell. The discovered mutation, as determined by his lab, promotes a new zinc equilibrium within the cell, resulting in a metabolic shift.
This led them to find that the mutation allowed Denisovans to deal with the cold, unfriendly climate that formerly destroyed Asia.
People’s sense of well-being and mental steadiness can be attributed, in part, to the role that zinc transport plays in regulating the excitability of the nervous system.
The researchers note that this zinc transporter is present in all human tissues and that the mutation detected in it is linked to an increased risk of developing specific psychiatric disorders.
Among these include anorexia, attention deficit hyperactivity disorder, autism spectrum disorder, bipolar disorder, depression, OCD, and schizophrenia.
It is believed that the Denisovans, who also inhabited western Asia and Europe during the same period as the Neanderthals, were a sister species to the Neanderthals.
Approximately 200,000 years ago, the two species appear to have diverged from a common ancestor, and about 600,000 years ago, they separated from the present human Homo sapien lineage.
Denisovan fossils were recovered in the same sediment layers as bone and ivory beads, suggesting that the Denisovans had access to sophisticated tools and jewelry.