In tomorrow's New York Times, I have an article about how new species evolve. It describes new research into how a population can split into two species. The idea that species can evolve when populations get geographically isolated is well-supported by evidence, but the idea that individuals living side by side can split apart (called sympatric speciation) has sparked more controversy. The late biologist Ernst Mayr was the lead champion of the geographic isolation mechanism, and he was always skeptical of claims of sympatric speciation. But, as he said in this 2001 interview, he was skeptical not so much of sympatric speciation itself, but of the particular cases that were made for it. That's continued to be the sticking point for a lot of evolutionary biologists. Two new cases--one concerning palm trees, the other fish--have impressed the critics I spoke to. I just wonder what Mayr would have said.