From Bruce Bower at Science:
Even more surprising, H. sapiens’ Stone Age dalliances outside their own kind weren’t limited to Neandertals. Ancient DNA shows signs of interbreeding between now-extinct Neandertal relatives known as Denisovans and ancient humans. Denisovans’ DNA legacy still runs through native populations in Asia and the Oceanic islands. Between 1.9 and 3.4 percent of present-day Melanesians’ genes can be traced to Denisovans (SN Online: 3/17/16). Other DNA studies finger unknown, distant relatives of Denisovans as having interbred with ancestors of native Australians and Papuans (see “Single exodus from Africa gave rise to today’s non-Africans”). Genetic clues also suggest that Denisovans mated with European Neanderthals.
These findings have renewed decades-old debates about the evolutionary relationship between humans and extinct members of our evolutionary family, collectively known as hominids. Conventional wisdom that ancient hominid species living at the same time never interbred or, if they did, produced infertile offspring no longer holds up.
But there is only so much that can be inferred from the handful of genomes that have been retrieved from Stone Age individuals so far. DNA from eons ago offers little insight into how well the offspring of cross-species flings survived and reproduced or what the children of, say, a Neandertal mother and a human father looked like.
But wait. We’re still here. And I went to school with girls who looked like that. So …?
Interbreeding is no rare event. Genome comparisons have uncovered unexpectedly high levels of hybridization among related species of fungi, plants, rodents, birds, bears and baboons, to name a few. Species often don’t fit the traditional concept of populations that exist in a reproductive vacuum, where mating happens only between card-carrying species members. More.
No, it isn’t a rare event. Hybrids are comparatively common in nature, it turns out, and lots of lazy ink gets wasted on that fact. Mainly because Darwinism prevents an honest discussion of the implications: What exactly does species, speciation mean anyway? What are the rules? Do they matter?
The implications of taking on “speciation” as a clearly demarcated concept in science are too serious, probably, even for the Royal Society, holding its big rethinking evolution meet next month.
See also: Neanderthal Man: The long-lost relative turns up again, this time with documents
Speciation: Red wolf not “endangered”; a hybrid?
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