Actually, Jim Shields, I have no doubt that most of what you said is true. In fact, anyone who knows well the history of science knows that this happens all the time. But let's not assume that when we lose sight of concepts we replace them with better ones; isn't it usually more a matter of replacing them with ones more suitable to the times? We live in a technology driven world: new technology will be used, for better or worse. In my view science is little different than music composition: it changes from generation to generation, and each generation tends to champion its own. But in the end, who is really to say that one sort is really better than another? That we will be defining a species by its DNA is to be expected. But fifty years ago the same thing could have been said about defining a species by its chromosome count. Fifty years before that it would have been gross morphology. In retrospect, we can say with confidence that chromosome counts and gross morphology simply didn't do the job well enough. And I'm confident that the time will come when scientists will admit that DNA studies couldn't do it either. That a new species concept will emerge from these DNA studies is to be expected, just as species concepts based on other sorts of morphology had their day. But just because the consensus in the community of scientists favors a particular view at a given time is no guarantee that another tool will not emerge allowing the next generation of young Turks to reshape things yet again. I agree mostly with your prediction for the future, "We will one day very soon be defining a species by its DNA, and the old definitions of "species" -- all of them, and several were really never very good anyway and all of them had problems -- will be lost sight of as science focuses on the molecular." But I think that when the modern species concept emerged in the last century, an intriguing cross fertilization of science and philosophy took place. DNA studies do the scientific part of the equation well, but my sense is that so far they ignore the philosophical part. No doubt an avalanche of new data will temporarily obscure this lack, but it's a shortcoming which won't go away. Thinkers will continue to ask "what does species mean?". Those who want to force an answer will have bulk data with which to bludgeon their way to an "answer". Taxonomy has always been beholden to various utilitarian considerations, and DNA studies will simply encourage that side of things to flourish. Science might abandon the concept of species, but if that happens I don't think it will be because DNA studies provide a better alternative. It will be because DNA studies make possible a more rigorous pursuit of the purely utilitarian considerations which traditionally have influenced taxonomic decisions. I made a musical analogy above. Earlier today I was listening to a Mozart composition about which the announcer had given a bit of background information. It seems that when Mozart took the piece to his publisher (who was a friend), the publisher told Mozart that he would not publish the piece because no one would be able to play it. Yet we know that people capable of playing it did eventually emerge, and now over two hundred year later it still makes musical sense. That's the way I think about the modern species concept: the time will come when there are people capable of playing it, and long afterward there will be those to whom it still makes sense. Jim Mc Kenney