How many new species have come along in the last, say, 10,000 years? Versus the number of species that have gone extinct in the same time period?
I mean, I think it’s sort of somewhat common knowledge that lots of things have gone extinct in the last few millenia – we’ve all heard of wooly mammoths, mastadons, dodo birds, sabre-toothed tigers, elephant birds, and so on and so on.
But how many new species have sprung up in the same timeframe? I don’t mean the genetically modified man-made ones, I mean like in nature?
One of the quirky things is how you define the word Species, of course. My understanding is that for a critter to be a distinct and separate species, it is capable of breeding with its own kind and producing viable (fertile) offspring. So you can tell two critters are not of the same species if either a) they can’t interbreed or b) they can breed but their offspring are themselves incapable of doing the same. (A good example would be Mules – a cross between a horse and a donkey. Aside from a few very rare exceptions, mules are not able to reproduce.)
This poses an interesting dillema though. How does a new species occur, if by (our) definition it cannot successfully mate with any other species? Like, if one animal were to mutate/evolve into something new, that would only work if there were other critters mutating/evolving in exactly the same way and exactly the same time, so that there was a breeding population that was always in sync and able to carry on. And this is actually probably what happens – there’s got to be some time of crossover where the ‘new’ species is still able to interbreed with the ‘old’ version, and during that time we might call them a sub-species or a variant, but not say it’s a truly new and separate species. At least, not till the variant had gotten so far from its original version that the two were no longer compatible.
And I’m babbling again, when really the question is simple. In the last 10,000 years, how many new species have come into being, verus how many species have gone extinct in the same time?
Is the world in a net-gain or net-loss of diversity at the moment?