A new study on DNA has revealed that people living today are only between 1.5% and 7% modern humans. No, this doesn’t mean that we’re over 90% alien (or are we...?), but it does indicate that we have very old DNA belonging to our ancient ancestors.
According to the study, only a very small percentage of our genome is uniquely human. Researchers extracted DNA belonging to skeletal remains of Neanderthals and Denisovans as well as from 279 people living in different parts of the world today. Then the experts took that information regarding sequenced genomes and developed a family tree for Homo sapiens, Neanderthals and Denisovans.
They found two important factors that really stood out: the first bombshell was that between 1.5 and 7% of our genome is unique to our species which means that at least 93% of our genome is a result of a mixture between Homo sapiens, Neanderthals, and Denisovans. The second discovery was that in the past 600,000 years, there were numerous bursts of genetic adaptations regarding brain development and function of humans.
By creating the evolutionary trees, the team of researchers were able to find very important times in history when Homo sapiens adapted and separated from our ancient ancestors. In order to find out how closely related we actually are to Neanderthals and Denisovans, experts had to study both the genes as well as when the genes were turned into proteins.
In an interview with Inverse, Nathan Schaefer, who is a bioinformatician at the University of California, San Francisco, explained this in further detail, “When you ask that question, we are very similar to Neanderthals.” “We have, you know, around 20,000 genes, and somewhere around 40 of them have these actual coding differences that all humans have one version, and the Neanderthals have the other version.” “That’s already like, ‘Wow, we’re really, really close to them.”
Fernando Villanea, who is a population geneticist at the University of Colorado, Boulder, but wasn’t involved with the study, told Inverse, “Their results support the most exciting new views on the interactions between humans, Neanderthals, and Denisovans.” He went on to talk about the human brain development over the past several hundred thousand years, “These adaptation events which define our species possibly happened around [600,000] and [200,000] years ago in Africa.”
In other words, this new study seems to indicate that the most genetically unique difference between modern humans and Neanderthals and Denisovans is our cognitive development over the past several hundred thousand years as explained by University of California, Santa Cruz computational biologist Richard Green, “We can tell those regions of the genome are highly enriched for genes that have to do with neural development and brain function.”
As for the researchers’ next steps regarding their studies, Schaefer stated, “What I’m interested in doing now is trying to learn more about how genes work and what these genes do.” The study was published in the journal Science Advances.