<p>“This would be the logical implication of a multi-origin theory, though – since it would be very unlikely for three groups of an ancestral species to independently evolve to become exactly the same new species, the logical conclusion is that, given a multi-origin model, human races would in fact be different species.”</p>
<p>I don’t see why. We see more isolated populations die out for lack of genetic variability than we do from a surfeit of it. The same ancestral species evolving independently in different environments and later interbreeding would produce hybrid vigor and in a species capable of communication and memory would the benefits would be even greater.</p>
<p>Whether “A single-origin theory is far more parsimonious, not to mention better supported by the available data.” is debatable. Parsimony is a little over-rated anyway. Whenever anyone mentions Occam’s Razor to me I am always remined of what the ignorant man I ever met used as an explanation whenever he encountered something he didn’t understand. He used to say, “It is a magical thing!” You cannot get any more parsim onious than that.</p>