One of those mysterious groups, you know, who start to appear more often in the fossil record as we dig more…
The now-extinct people that we call Denisovans actually consisted of three distinct groups of humans spread throughout Eurasia, the researchers say. And one of those groups might well even be considered its own species. Ancient humans would have interbred with all three of these lineages on multiple occasions, as Neanderthals, Denisovans and Homo sapiens swapped genetic material in a process that has left Denisovan DNA still residing in our cells today… Perhaps the most significant way that the new genetic evidence alters our conception of the Denisovans is that it reveals them to be diverse. In some modern Indonesians, scientists found not one, but two distinct Denisovan genomic signatures. What’s more, these two groups also looked different from the Denisovans previously found in Siberia, which they researchers say was another group altogether. For those of you keeping count, that adds up to three different kinds of Denisovans spread from Siberia to across the disparate islands of Indonesia. Nathaniel Scharping, “The Denisovans May Have Been More Than a Single Species” at Discover Magazine
Just what the concept of “speciation” adds to the human picture is unclear. But it makes for news stories.
The paper in Cell is (open access):
Summary: Genome sequences are known for two archaic hominins—Neanderthals and Denisovans—which interbred with anatomically modern humans as they dispersed out of Africa. We identified high-confidence archaic haplotypes in 161 new genomes spanning 14 island groups in Island Southeast Asia and New Guinea and found large stretches of DNA that are inconsistent with a single introgressing Denisovan origin. Instead, modern Papuans carry hundreds of gene variants from two deeply divergent Denisovan lineages that separated over 350 thousand years ago. Spatial and temporal structure among these lineages suggest that introgression from one of these Denisovan groups predominantly took place east of the Wallace line and continued until near the end of the Pleistocene. A third Denisovan lineage occurs in modern East Asians. This regional mosaic suggests considerable complexity in archaic contact, with modern humans interbreeding with multiple Denisovan groups that were geographically isolated from each other over deep evolutionary time.Guy S. Jacobs, Georgi Hudjashov, Lauri Saag, Herawati Sudoyo, J. Stephen Lansing, Murray P. Cox , “Multiple Deeply Divergent Denisovan Ancestries in Papuans” at Cell April 11, 2019DOI:https://doi.org/10.1016/j.cell.2019.02.035
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See also: A physicist looks at biology’s problem of “speciation” in humans
Shakeup! New human find from over 50,000 years ago shows our ancestors were smarter than once thought A news roundup. J. R. Miller points out, however, that a lot of the “news” is face-saving hype