Reply #16: Evolution tends to occur in small, isolated groups [View All]

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That's the only way new traits can take hold and be combined into a genuinely new adaptive pattern. Anything else is just minor tweaking and optimization.

The last major evolutionary change was the one which produced Homo sapiens sapiens about 170,000 years ago. There was a more superficial burst of change about 20,000 years ago which produced the present-day "races" -- a lot of evidence suggests that until then people everywhere looked pretty much like Polynesians or Australian Aborigines, and that the distinctions in skin and eyes and hair which we see around us today were the result of sexual selection as people became less driven by raw survival needs and had the leisure to consider prettiness instead.

That sort of sexual selection could certainly continue, even on a global basis. Perhaps 20,000 years from now, we will all have blue eyes, high Oriental cheekbones, and medium-brown skin. But any development of a genuinely new human species seems extremely unlikely.