Neanderthal DNA In Our Populations: Yea Or Nay?
The Neanderthals might have left our planet 40, 000 years ago, but they have not completely faded. They’re still a part of us, existing through our genes.
The Neanderthals appeared in Eurasia circa 400, 000 years ago after their ancestors left Africa. DNA analyses have shown that the genomes of most European and Asian populations comprise 1-2% Neanderthal DNA. Genomes of Melanesians and Africans show traces of other hominins such as Denisovans and Homo heidelbergensis, though we will not go into detail on that as there is still limited understanding on those. One thing is clear, though – the modern humans of today did not all arise from one founder species; depending on where we draw our roots, different hominins form part of our ancestry.
So, does having Neanderthal DNA influence us today in any special way? There are studies show that possessing this archaic DNA contributes to height, hair texture, tolerance to alpine altitudes and an enhanced sense of smell. A study conducted at Stanford University in 2011 suggested that carrying Neanderthal DNA means we have a number of ancient gene variants associated with improved immune function against certain pathogens.
Janet Kelso, a computational biologist from the Max Planck Institute for Evolutionary Anthropology, conducted a detailed study using information from the UK Biobank – a database of genetic and health parameters from at least 500, 000 volunteers from the UK. Sufficient analysis could be done with this wealth of information with regard to measuring the influences of Neanderthal DNA on modern populations. This study also corroborated that having Neanderthal DNA is a bonus when it comes to immune function. However, other fascinating, almost peculiar, observations were seen – people with Neanderthal gene variants were more likely to smoke, suffer from sunburns and mental illness and were more evening than morning people. Overall, Kelso believes that while several genes could have been of selective advantage to the Neanderthals who lived a hunter-gatherer life in harsh environments outdoors, they might not be entirely useful for humans of today who largely live sedentary lives indoors.
Along the same lines, computational biologist Tony Capra from Vanderbilt University in Nashville (Tennessee, USA) who studied the genetic database of 28, 000 Americans stated that Neanderthal DNA variants in individuals with Eurasian ancestry increased the likelihood of depression, blood clots and skin lesions, among other disorders.
Reading about the slew of less-favourable traits the Neanderthals have left in their wake sounds rather dispiriting, doesn’t it? However, recall that Neanderthal DNA makes up only a fraction of our genome. In the larger scheme of things, these gene variants probably do not influence us or alter our lifestyles significantly. The amount of DNA an individual shares with Neanderthals or any other hominin means little with regard to possessing selectively advantageous traits like strength or intelligence, considering thousands of years of human evolution have passed, with factors like natural selection is slowly weeding out less-desirable traits from our gene pool. The abovementioned studies are more or less preliminary; in-depth research still needs to be carried out to come to conclusive findings.
By Mallika Venkatramani – Science Writer