Definition of species under attack?

  1. I learned that two sexual organisms are considered different species when no two organisms having their respective DNA structures could interbreed to produce viable offspring. Put another way, when looking it up, I find the definition:
    But then I read that:
    (a) Neanderthal interbred with homo sapiens to give part of today's modern man
    (b) Neanderthals is a different species from homo sapiens.
    Hence, the above definitions don't seem to hold. Can someone correct these definitions in light of this?
  2. jcsd
  3. atyy

    atyy 11,119
    Science Advisor

  4. Thank you for your reply and the links, atyy.
    If I understand correctly (no guarantee of that), all the links you sent all roughly say that it is a fuzzy area:
    (1) leans towards "Biological Species Concept", similar to my rough definitions but nuanced due to unusual cases,
    (2) leans more towards a phylogenetic interpretation of species whereby physical features are the primary criteria which are of course influenced by genetic isolation
    (3) says that whichever concept you take, it is still not clear whether the Neanderthals were indeed a separate species.
  5. atyy

    atyy 11,119
    Science Advisor

  6. Perhaps you have heard of ring species

  7. Thanks, atyy. Very interesting article.
    thorium 1010: very interesting about ring species; no, I hadn't known.
    As far as the other Wiki article you cited, the one you quoted, read a bit further down, where it says
    That cleared the way for the more recent articles (such as the article that atyy just cited) which continue to test the assumption that interbreeding may have occurred.
  8. Sure, but would you call something 99.5% similar to us, a different species ? Thats the important question, where would draw the line for species ?

    Species in biology is somewhat of a grey area, it is not black and white as we think it is.
  9. Indeed, that was my original question, and the answers showed me that it is indeed a fuzzy concept.
  10. I think the fact that there is small amounts of Neanderthal DNA in modern Europeans proves that Neanderthal were not a different species in the classic sense of "species".

    I think what happened was that there was a minor amount of inner breading but mostly the Neanderthal were out competed. In those days, 30K yeas ago, I think the Neanderthal population would have been equilibrium with the food supply. Then come these other guys who like to eat the same food. We modern humans eat their food so they remained in equilibrium with a shrink food supply. And I'm sure there was a very rare hybrid born now and then.
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