I am tempted to say, "as you should know"...
But I wo...too late. :-)
In any case the issue is that trials do not equal success. When we look at the fossil record we see skeletons with clearly distinct features. The question is whether those skeletons are different species (can't interbreed), or different races/sub-species (can and occasionally do). (Of course it is less clear-cut than that, the boundary between what are and aren't considered different species is sometimes a little nebulous. A basic concept that seems to continually confuse Creationists...)
So while there is little question that our ancestors would have tried to mate, did those attempts produce viable offspring that got into our evolutionary line? The existence of individuals with a mixture of traits does not actually answer that. Those individuals could have been like mules, perfectly capable of existing, but irrelevant to anyone's future genetics.
Cheers,
Ben
