What amount of genetic variance between two groups of humans would account for / trigger a classification of a different species?
That is, is there a quantifiable amount of variance between say, a fruit fly and a different kind of fly, beyond which it is apparent they are two different species? Something like "2% of genetic variance, therefore a new species"?
Any sort of search on Google only turns up racist sites - apparently "genetic distance" is a codeword for rather unfriendly attitudes towards blacks - obviously I don't know the right technical terms to look for.
Species are an attempt to label a continuous phenomenon with discontinuous labels. Sometimes the cutoff point is the ability to produce fertile offspring, but that doesn't work all the time. It's always going to be very subjective.
Well put. I kept thinking this as I read the article. The notion of species is useless in understanding the phenomena the article discusses.
I'd go so far as to say that the word "species" causes significant confusion even among scientists, since it so biases the way one thinks about collections of similar organisms.
My hunch is that the "species bias" comes from the heavy influence of religious views of "creation" rather than "emergence" in Western culture.
My, layperson, understanding is that if they can interbreed and produce fertile offspring, then they are the same species. So two types of fly that can't inter-breed would be classified differently.
I don't think that's quite accurate (for example, ligers are capable of reproduction, though they would never be born 'naturally' due to the vast geographical separation of lions and tigers in the wild) but it might point you in the right direction.
For a long time, that was also my impression. But it's wrong. Mostly.
It turns out that there isn't a single definition for the word species—there are multiple definitions that lead to different results. Reading through the Wikipedia article about species will give you a sense of the different definitions. http://en.wikipedia.org/wiki/Species
If you use the Biological/Isolation species definition, I think you could argue that humans are or were multiple species. (Please, someone correct me if I'm wrong on this.)
That is, is there a quantifiable amount of variance between say, a fruit fly and a different kind of fly, beyond which it is apparent they are two different species? Something like "2% of genetic variance, therefore a new species"?
Any sort of search on Google only turns up racist sites - apparently "genetic distance" is a codeword for rather unfriendly attitudes towards blacks - obviously I don't know the right technical terms to look for.