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Instinction

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This is a prime candidate for an MFD on the basis that it's not an invention but is a naming. It may also be considered MFDable on the grounds of bleedin' obviousness, but time will tell.

On the plus side, it's not a recipe.

In another discussion here, the topic of extinction came up in the context of mankind's possible future demise. The point made was that, of all the species that have ever lived, the overwhelming majority have become extinct at some point.

Well, no they haven't. At least not the overwhelming majority.

Consider the thylacine (Tasmanian tiger or marsupial wolf) and Australopithecus. The thylacine is certainly extinct (as far as we know), and there was a precise moment when the last member of the species died, in a zoo. Game over.

On the other hand, if our understanding of human evolution is correct, there was never a last Australopithecus. The species (actually Australopithecus is a genus, but I'm thinking of whichever species is our distant ancestor) evolved, and eventually became so different that we recognise it as a different species, Homo habilis (there is a lot of argument about the details, but you get the idea). Homo habilis then evolved into Homo heidelbergensis, which then evolved into Homo sapiens.

The point is, there is no time in pre-history when an Australopithecus, Homo habilis or Homo heidelbergensis could look around and say "I'm the last of my species". All of those species are extinct, but none of them went through a process of extinction.

Similarly, the ten million or so species alive today are not the only species that have not yet become extinct. Each of those species can trace its ancestry back through a chain of previous species. Any species which lies on a path from the first life to a living species cannot be said to have undergone extinction in the same sense as the thylacine.

Of course, many species, like the thylacine, failed to leave any descendent species; and all of today's species share common ancestors. But, nevertheless, it is a misconception to say that today's surviving species are the only "non-extinct" ones.

This is particularly true when catastrophists argue that, since most species have become extinct, humans are likely to become extinct too. To say that is to say that Australopithecus became extinct, which in turn is to say that our distant ancestors became extinct.

Get to the point [Buchanan].

OK. My point is this. It would be useful, in discussions of evolution, to distinguish clearly between species which simply stop, such as the thylacine, without leaving any descendant species; and those which become 'extinct' only in the sense of giving rise to a new species.

If there is any invention in all of this rambling (which I doubt gravely), it is the proposal of a new term which distinguishes these two types of 'extinction'.

MaxwellBuchanan, Nov 08 2011

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       // those which become 'extinct' only in the sense of giving rise to a new species //   

       Such as, say, *homo erectus*.
Alterother, Nov 08 2011
  

       It's a question of speciation. If the original line split, evolved into another species, and then the original went extinct, that's still a true extinction, as there was a speciation event.   

       If instead, the species, in its entirety evolved, then it is questionable whether the two variations can truly be considered separate species, as no speciation event occured (to whit, there was never a point where living memebers of the "different species" couldn't interbreed).
MechE, Nov 08 2011
  

       //If the original line split, evolved into another species, and then the original went extinct, that's still a true extinction, as there was a speciation event.//   

       Well, I disagree. Take humans and Neanderthals (ignore any of the speculation about inter- breeding, let's keep it simple). They could both trace their ancestry back through Homo habilis (say). After the split which led to Neanderthals and Homo sapiens, Neanderthal's went extinct, in an absolute sense. Clearly Homo sapiens is not extinct. Is it true to say that their common ancestor (habilis) went extinct in the same sense that the Neanderthals went extinct? It's possible to imagine the last Neanderthal dying with no children; but it's not possible to imagine the last Homo habilis dying with no children, or we would not be here.   

       Technically, if a species "as a whole" evolves, then technically there wouldn't be an extinction; but we would look back at the fossil record and call two or more species, even if we had difficulty partitioning them; we'd still say the original species was extinct. (And I am not suggesting that evolution is a smooth, continuous process; therefore we often see distinct species, and only rarely find the intermediates, even if the species evolved 'as a whole').   

       The point I was making is that there are huge numbers of species which we call 'extinct' but which, as ancestors of extant species, cannot be cited as evidence for the idea that all species (including humans) to have gone through a process of extinction, even though they become extinct.   

       To come back to the debate that prompted this, if your great^n granddaughter has diverged to the extent that neither she nor her fellow people are called "Homo sapiens", you wouldn't really look back and say that Homo sapiens went the way of the thylacine.   

       In the end it's all semantics and hot air, but it becomes important when someone says "99.99% of all species to have lived are extinct, so that's the way humans will go".
MaxwellBuchanan, Nov 08 2011
  

       Species 'rebounding' (or 're-evolving' by convergent evolution) is sort of a seperate issue.   

       What I'm arguing is that evolution should be viewed as the same way as we view the ancestry of individual people. My great^5 grandfather Merrydick and his brother Orsten are both extinct. But Orsten is more extinct than Merrydick because, in a triumph of heredity, he's my great^5 grandfather, whereas Orsten (wisely) died without bearing fruit.   

       So, Merrydick and Orsten are both extinct, but Orsten is the extincter of the two.
MaxwellBuchanan, Nov 08 2011
  

       To put it another way, if you managed to bring an Australopithecus and a Neanderthal back from the dead, the Australopithecus would say "Wow, we've really made that bipedalism thing work, haven't we?" whereas the Neanderthal would say "Oh bugger, and we thought it was all going so well."
MaxwellBuchanan, Nov 08 2011
  

       Yes (although I did say 'ignore the speculation about interbreeding'). All sorts of scenarios are possible, and will have occurred.   

       But I still contend: there's an difference between a species which is a dead-end, and one which wasn't.
MaxwellBuchanan, Nov 08 2011
  

       //Is it true to say that their common ancestor (habilis) went extinct in the same sense that the Neanderthals went extinct?//   

       I didn't say it was. In that case you have a speciation event leading to two species (Neandertal and Sapiens) but in both cases it was probably a gradual evolution of isolated populations, so neither experienced true extinction, although one of the lines later did.   

       //but we would look back at the fossil record and call two or more species, even if we had difficulty partitioning them; we'd still say the original species was extinct//   

       I would suggest that this indicates a problem with our definition of species.   

       //And I am not suggesting that evolution is a smooth, continuous process; therefore we often see distinct species, and only rarely find the intermediates//   

       I would suggest that our definition of a species is heavily influenced by what we find, leading to observer bias. It's not so much that we don't find intermediates as that we define a given species by the fossils most likely to be recovered, and consider gaps to be the intermediates.   

       This may result from various things, including the possibility that the intermediate species is just less likely to leave fossils owing to a change in environment.
MechE, Nov 08 2011
  

       // so neither experienced true extinction, although one of the lines later did.// OK, we agree on that. I was focussing on the common ancestor (habilis), which (by my 'definition') didn't become extinct in the strict sense.   

       //I would suggest that this indicates a problem with our definition of species// Yes, certainly, but again that's a horse of a different feather.   

       //our definition of a species is heavily influenced by what we find// Yes, that too, of course.
MaxwellBuchanan, Nov 08 2011
  

       hmm... what's that buzzword used to mean "fucked over" ? That would fit.   

       deprecated.
FlyingToaster, Nov 08 2011
  

       //"Oh bugger, and we thought it was all going so well."// [marked-for-tagline]
po, Nov 09 2011
  

       It would be useful to have a different term, but the trouble is, when would you have a firm basis for supposing that one thing has happened and not the other? I also think there are many examples of genuine extinction, for instance creodonts and Australopithecus robustus, as opposed to other Australopithecines which did leave descendants.   

       Also, well yes, we might evolve, but why would we evolve into anything that matters to us, i.e. anything which is intelligent? Isn't it possible, for example, that we might survive as a transmissible pathogen on other species or tubular brainless things at the bottom of the ocean?
nineteenthly, Nov 09 2011
  

       //transmissible pathogen on other species// An *intelligent* transmissible pathogen on other species? Might not differ all that much from our present phenotype.   

       (Just quibbling. Another case where it's hard to tell if one thing has happened and not the other. Your point is sound.)
mouseposture, Nov 09 2011
  

       //the trouble is, when would you have a firm basis//   

       Well, nothing much is ever for sure in evolution. However, we have fairly good palaeophylogenetic trees, in which "extinct" species are placed in relation to others. They're very far from complete or correct, of course, but they're the best we can do. Thus if, on the current interpretation of human evolution, Australopithecus afarensis lies on the path to humans, its not "extinct" in the same way that, say, Homo neanderthalis (which, crudely speaking, is the terminal point on a branch) is "extinct".   

       Even though there will be lots of uncertainties, and the status of species will change as we learn more about their relationships, these details are almost secondary to my broader point. This broader point was that it's wrong not to distinguish between a "dead end" species and one which went on to give rise to a successor species.   

       There was a last thylacine who died without offspring; there was never a last Australopithecus who died without offspring. That's the crystallization of the idea.   

       //would we evolve into anything that matters to us, i.e. anything which is intelligent?// In a sense, that doesn't matter, because if we evolve into something non-intelligent we won't really be in a position to care.
MaxwellBuchanan, Nov 09 2011
  

       But [19thly]'s point was that that eventuality ought to count as extinction. Or might be held to ought to.
mouseposture, Nov 09 2011
  

       Well, many (if not most) extant parasites have descended from free-living organisms. I guess you'd call it an evolutionary demotion.
MaxwellBuchanan, Nov 09 2011
  

       //In a sense, that doesn't matter, because if we evolve into something non-intelligent we won't really be in a position to care.//   

       Wow, maybe that explains why I just can't be arsed about many things...   

       We're all just multi-celled extensions of bacteria, placed here to host them.
RayfordSteele, Nov 09 2011
  

       //demotion// Odd, that. In societies, evolution into a parasite can be associated with either a fall *or* a rise in status.
mouseposture, Nov 09 2011
  

       // We're all just multi-celled extensions of bacteria, placed here to host them. //   

       Now that's a theory I can get behind.
Alterother, Nov 09 2011
  

       Lactobacillus Bulgaris. You're only multicultural if you eat yoghurt.   

       // Homo habilis then evolved into Homo heidelbergensis, which then evolved into Homo sapiens //   

       {MB], we have something to tell you in private about Black Monoliths, which you may find a trifle upsetting to your view of your world and its "history". Please sit down in a comfortable chair, grasp the flagon of Single Malt Whisky being proffered by the flunkey, and take an number of very deep breaths. It won't help, but you go a very amusing colour when you hyperventilate.
8th of 7, Nov 09 2011
  

       By fortuitate coincidence, I am already seated in a very comfortable chair. A flagon seems a trifle excessive, but I do have a generous glass of Highland Park '58 (I don't normally bother with the cooking whisky, but I didn't have the heart to send old Meniscus back down to the cellar again).   

       Oddly enough, the intercalary twin was recently troubled by what I believe you call a 'hive mind'. It was only when he started falling over more than usual that he realized that the little blighters had chewed off the middle six inches of his wooden leg. Permethrin, apparently, was the most convenient solution.
MaxwellBuchanan, Nov 09 2011
  
      
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