The experiment was quirky but profound. If two groups of the same insect ignore each other and only mate within their social circles, they should eventually split into distinct species. These splits occur all the time in nature, and the forces that cause them can take many forms. They could be physical obstacles like mountains or rivers. They could be differences in timing, in the hours or seasons in which animals are active. They could be incompatible genes that prevent two animals from interbreeding. Anything that stops animals from mating, or that kills or weakens the offspring of those
...more
