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The most obvious worry about the "new" science of defining species by DNA analysis, is that we will eventually "prove" humans are no longer one species. The of

The most obvious worry about the "new" science of defining species by DNA analysis, is that we will eventually "prove" humans are no longer one species. The official scientific definition of species is old and very well known and very well defined. A species breeds successfully with itself. If you can't produce fertile offspring then you are two species. Horses and Donkeys are two species because mules can not reproduce. Even if A + B = C, and C + C = D, if D + D = nothing, then A and B are separate species. So no matter who or what we interbred with, or how large our genetic differences are, we are obviously one species. And or "large" genetic differences are actually tiny compared to what you can find in say chimpanzees.

lifeisstillgood 14y ago
Edit: Trying to be clearer The official definition of species seems to be shifting. The article claims that humans interbred with Denisovans, implying that the offspring were viable and lead to us, and that they could distinguish between ancient humans and Denisovians via DNA testing. That implies to me, that Denisovians and Humans are distinct species, and can be told apart by some DNA testing. I am interested in the process of defining of species via DNA - the implications for that seem reasonable to infer given our unpleasant history. What did they measure - which part of the genome did they say is human and which Denisovans. Are those sequences ever found in modern humans? Could they be? What would that human who had more Denisovian DNA than typical be called? Why? There are two things here - the scientific metrics used, and the political decision to turn metrics into loaded words like species. I can argue all day over the second but I have no infomration on the first.
- fghh45sdfhr3 14y ago
  That implies to me, that Denisovians and Humans are distinct species, and can be told apart by some DNA testing. You can tell apart almost any two groups of modern humans with DNA testing. You can tell apart paternal twins with DNA testing, that doesn't make them two different species. Are those sequences ever found in modern humans? Yes. Could they be? Yes. What would that human who had more Denisovian DNA than typical be called? Well today Neanderthal DNA in humans can range from almost nothing to as much as if your great grand father was pure Neanderthal. What do we call either extreme? Human.

lifeisstillgood 14y ago

Edit: Trying to be clearer The official definition of species seems to be shifting. The article claims that humans interbred with Denisovans, implying that the offspring were viable and lead to us, and that they could distinguish between ancient humans and Denisovians via DNA testing. That implies to me, that Denisovians and Humans are distinct species, and can be told apart by some DNA testing. I am interested in the process of defining of species via DNA - the implications for that seem reasonable to infer given our unpleasant history. What did they measure - which part of the genome did they say is human and which Denisovans. Are those sequences ever found in modern humans? Could they be? What would that human who had more Denisovian DNA than typical be called? Why? There are two things here - the scientific metrics used, and the political decision to turn metrics into loaded words like species. I can argue all day over the second but I have no infomration on the first.

fghh45sdfhr3 14y ago
That implies to me, that Denisovians and Humans are distinct species, and can be told apart by some DNA testing. You can tell apart almost any two groups of modern humans with DNA testing. You can tell apart paternal twins with DNA testing, that doesn't make them two different species. Are those sequences ever found in modern humans? Yes. Could they be? Yes. What would that human who had more Denisovian DNA than typical be called? Well today Neanderthal DNA in humans can range from almost nothing to as much as if your great grand father was pure Neanderthal. What do we call either extreme? Human.