Kicking the legs out from under a too old dogma
UNdiscovery, variation is not just across species! Turns out we did not get lucky and on the first go find skulls that fully and accurately described the complete course of speciation events in human beings!
As excavations at Dmanisi continue, researchers expect to find more fossils — and perhaps more conclusive proof that normal variation within a single Homo species has been misinterpreted as species diversity. It might be time to rewrite the evolutionary history books.
ᔥ from http://bit.ly/UNdiscovery
Given the sparsity of the samples, this is in no way surprising to me. I could never believe that we were basing so much on so little data anyway, especially given the likely theoretical concerns.
At any point in time, if evolution is to occur there will need to be some amount of variation in the population, if the fossil record is completely randomly sampled (ignore the ambiguity there...) we would expect not just to have individual specimens from massively different species, but we would see a good amount of within generation variation.
This is more generally related to the problem of treating animal species as if they are individual prototypes (or even more ambiguously, archetypes) as opposed to a distribution that has natural variation between individuals of the species.
And all these critiques don't even address the issues having to do with the platonic assumptions that go into the notion of a 'species' such that it could have an 'archetype' anyway.
Here's a secret...species don't evolve, indeed, they don't even exist. individuals evolve and species are useful conceptual boxes that we put around populations of those individuals in saying that they're effectively the same. However if we are going to have a picture of evolution that reflects the processes that we can actually expect to observe then we need to move away from this 'ideal instance of a species' idea. Identifying species is hard and mistake prone, so lets let our categories rest and use them as needed rather than declaring once and for all we know that this is a representative of one species or that is a representative of another species.
Variety is not just the spice of life, it is life.
Evolution is a gradient process, and, yes, sometimes a saltatory one, and both types of change need variation and that variation will need to be smooth enough that we can even recognize it as variation. But this is just a more rigorous example of us having missed the forest for the trees...or more so the tree...or more so maybe a branch or two. If you look hard enough at anything sufficiently complex your ability to find dimensions you could use to say that they were different kinds of things...but why be more precise than your data warrant unless you need to...and it doesn't seem like we needed to here.
Acknowledgements
A good friend me the idea of "humanish". pure brilliance.