The legacy of Denisovans still lives on in modern humans. Scientists have found that some people currently living in Papua New Guinea have an immune system that's partly coded by DNA inherited from Denisovans, a mysterious extinct species of archaic hominins that humans once widely interbred with.
Reported in the journal Cell, researchers from the Wellcome Sanger Institute looked for structural variations in the genomes of 911 people from 54 diverse populations across the globe, including many groups of people that have previously been understudied by scientists.
Large-scale genetic studies typically focus on single base pairs of DNA, but this study looked for what’s known as structural variations, a region of DNA that can encompass anything from a small number of base pairs of DNA to millions. Within the research, some 126,018 new structural variations were discovered, many of which could shed light on the history of humankind and even inform modern medicine.
"Structural variants are complicated yet very important functionally, evolutionarily and medically,” Dr Yali Xue, recently retired from the Wellcome Sanger Institute, said in a statement. “The discovery of these new structural variations provides one of the richest resources of this kind of variation so far, which not only offers unique insights into population histories and improves the currently used human reference genome, but will also substantially benefit future medical studies."
Among genomes sequenced from people living in Oceania, such as Papua New Guinea and some surrounding locations, the team managed to find a number of genetic variations that appear to have been inherited from Denisovan ancestry. The variation in question affects the AQR gene, which plays a role in immune response and the detection of viruses.
The idea of having the DNA of an ancient extinct human species might seem strange, but it’s surprisingly common. After all, humans are known to have widely kanoodled with Neandtherhals and Denisovans before they went extinct. Denisovans and Neadntherals are also known to have interbred with each other, just to make this love triangle even more complicated.
Almost every human population on the planet contains some hint of Neanderthal DNA, although it's most common in people of European descent. It’s been speculated that some relics of Neanderthal DNA may even influence the risk of depression and heart attacks in modern-day humans. Research from 2014 found that people living in the mountainous region of Tibet have inherited a gene variant from Denisovans that affects their blood oxygen and allows them to thrive in high-altitude regions.