“Scientists say an African-American male’s odd genetic signature suggests that the human Y chromosome’s lineage goes back further in time than they thought — perhaps due to interbreeding with other populations such as Neanderthals.”
It probably isn’t Neanderthal, since most Neanderthal DNA seems to be in Europeans and North Asians, nor Denisovan, since their legacy seems primarily to lie with Melanesians and Australian Aborigines. It’s possibly another unknown hominin in Africa, which might be associated with in some way what Gregory Cochran has joked that we should call Mangani. (Peter Frost here speculates on African admixture with various archaic hominins.)
The NBC article continues:
That goes further back than the fossil record goes for anatomically modern humans, Hammer said. “The fossil record speaks to 195,000 years or 200,000 years,” he said. It also goes further back than the previous date for the most recent common ancestor based on Y-chromosome analysis, which is in the range of 142,000 years….
Melissa Wilson Sayres, a geneticist at the University of California at Berkeley who played no role in Hammer’s study, said the new findings were “exciting” because they pointed to a Y-chromosome lineage more ancient than any others. “They just happened to come across this one Y chromosome that was hidden for so long, and it’s very likely that there are more hidden Y chromosomes around the world,” she told NBC News.
She said one of the biggest debates in the study of human genetics has to do with how to match mutation rates with time scales — and she expects this latest study to add to the debate. For example, some might continue to argue that the most recent common ancestor lived more recently than 338,000 years ago. “It will still be the oldest Y-chromosome heritage that we have, but I can foresee that some people might disagree with that specific age,” she said.
In the long term, this might refine our understanding of genetic distances (and genetic lineages) among the races – in that the various races are not even completely the same species. As Cavalli-Sforza’s team found:
“Cavalli-Sforza’s team compiled extraordinary tables depicting the “genetic distances” separating 2,000 different racial groups from each other. For example, assume the genetic distance between the English and the Danes is equal to 1.0. Then, Cavalli-Sforza has found, the separation between the English and the Italians would be about 2.5 times as large as the English-Danish difference. On this scale, the Iranians would be 9 times more distant genetically from the English than the Danish, and the Japanese 59 times greater. Finally, the gap between the English and the Bantus (the main group of sub-Saharan blacks) is 109 times as large as the distance between the English and the Danish.”
Will these distances even widen in a conceptual sense as we find out about new lineages?