How would we recognize it when and if homo sapiens evolves into a distinct species?

[ChrisC]

Let's say an isolated population on an island started to evolve separately from the rest of mankind. At what point and how would we tell when this had become a separate species from the rest of us? Could it be said this has happened already but this issue is too politically charged to allow us to say it has happened already. For instance if the only two populations of homo sapiens were the short pygmies in Africa and the large Eskimos in the Arctic. Might someone be tempted to argue they came from different species? If not why not?

 

[truthseeker]

There's still no 'irrefutable' proof for evolution, Chris. But that apart, two species are said to be different if they can't 'properly' interbreed. So, if the tiny African pygmies can reach up and 'mate' with the gigantic Eskimos, assuming that the coldness of the Arctic didn't affect them too adversely, they'd be considered the same species.

 

[andymanec]

They'd be a distinct species when the sub-population became unable to inter-breed with the main population. To my knowledge, that hasn't happened yet, but there's no reason that it couldn't happen, given enough time and enough isolation. All humans came from the same species, though. We may diverge into different species eventually (but probably not, unless we nuke ourselves back to the stone age or something), but we definitely did not converge from multiple different ancestral species.

"Species" is always a tricky definition, though. We're taught in school that it's a hard-and-fast rule, and different animals neatly fall into separate species. In reality, the lines between one species and another can get blurry. Sometimes two different (but very closely related) species can reproduce, and have fertile offspring. Life is nothing, if not flexible, and seems to love keeping us from neatly categorizing it.

 

[UKGuy1]

Flip that round and think of a Chiuaua ot a Pikanese, then think of a Great Dane or a German Shephers or a St Bernard. They are all dogs. Horses have been mated with zebra's and donkeys which are considered different species but have more similarities on the surface than some dogs.

For a species to be isolated I believe there has to be some defining feature though i dont believe skin colour or fur colour is legitamate.

To an extent from where I'm sitting it all seems a bit arbetrary.