It is human nature to want to know where you come from—who your family is, where they lived, what their lives were like. Breakthroughs in DNA technology have made it possible for the average person to take an at-home test to determine their family’s ethnic origins. Researchers with the Neanderthal genome project are taking that investigation once step further with their look into the connections between modern humans and Neanderthals, including the latest information about UV-light adaptations. These DNA mutations indicate that the two groups may have more in common than was originally believed.
Early human interbreeding
According to researchers at the University of California, Berkeley, there has been a long history of interbreeding among at least four different types of early humans who lived in Europe and Asia about 50,000 years ago. Robert Sanders posted on December 18, 2013, for UC Berkeley’s News Center, “Neanderthal genome shows evidence of early human interbreeding, inbreeding,” that one early group, the Denisovans, and the Neanderthals were very closely related genetically. The two groups’ common ancestor split from modern humans’ ancestor about 400,000 years ago; then the two groups split from each other about 300,000 years ago.
Sanders wrote, “Though Denisovans and Neanderthals eventually died out, they left behind bits of their genetic heritage because they occasionally interbred with modern humans. The research team estimates that between 1.5 and 2.1 percent of the genomes of modern non-Africans can be traced to Neanderthals.” Ultimately what the scientists have found is that there is a complicated history during that period with lots of interbreeding, some of which we have yet to uncover.
The discovery by scientists, that humans and Neanderthals once interbred, led the researchers to take a more in-depth look at what traits modern humans may have inherited from Neanderthals. This initial discovery of the Neanderthal genome revealed that humans shared 5 percent of their DNA with the group. Catherine Griffin reported on December 13, 2013, for Science World Report in “Sunlight Adaptation in Humans Inherited from Neanderthals,” about the researchers’ findings. She wrote, “The scientists found evidence of a Neanderthal DNA region found on chromosome 3 that contains 18 genes, with several related to UV-light adaptation.”
In addition, the researchers uncovered that “the geographic distribution of the Neanderthal genomic region suggests that UV-light mutations were lost during the exodus of modern humans from Africa.” According to Griffin, Neanderthals then reintroduced these mutations to Eurasians.
The Y Chromosome
Equally fascinating in terms of determining the origins of modern humans is a discovery by geneticists from the University of Arizona, Tucson. In “Human Y Chromosome Is One for the Ages,” which appeared in the June 2013 issue of the USA Today magazine, it shares that the researchers found the oldest known genetic branch of the human Y chromosome. What made this discovery helpful was that most Y chromosomes do not share genetic material with other chromosomes. That means that it is simpler to trace ancestral relationships among contemporary lineages.
For example, the article said, “If two Y chromosomes carry the same mutation, it is because they share a common paternal ancestor at some point in the past. The more mutations that differ between two Y chromosomes, the further back in time the common ancestor lived.” The new lineage that the researchers in Tucson found diverged from the Y chromosome tree “before the first appearance of anatomically modern humans in the fossil record,” the article stated.
All of this knowledge helps scientists learn about changes in human lineage and what made all of the expansion and development among the human populations possible over the last 100,000 years. But it is certainly an area that is ripe for further exploration and research as our current technology and understanding expands.
Are you fascinated by the connections between humans’ long-ago ancestors? Do you think there are more similarities that will be discovered? Share your thoughts in the comments below.