At first glance, “species” is a basic vocabulary word schoolchildren can ace on a test by reciting something close to: a group of living things that create fertile offspring when mating with each other but not when mating with outsiders. Ask scientists who devote careers to designating those species, however, and there’s no typical answer. Scientists do not agree.
Philosophy Chair Matt Haber addressed this tricky question in the latest cover story of Science News. He agreed there is a lot of confusion and messiness in picking out the limits of species, but as a philosopher, he is comfortable in that space. Haber organized three conferences at the U this year on the complications of determining what’s a species when fire hoses of genetic information spew signs of unexpected gene mixing and tell different stories depending on the genes tracked.
“Just because boundaries are fuzzy,” Haber says, “doesn’t mean they aren’t actually boundaries.” We may not be used to thinking about species distinctions this way, but other familiar distinctions have similar “gradient boundaries,” as he calls them. “Cold and hot weather,” he says. We recognize winter weather as different from summer even though fall and spring have neither a sharp switch point nor a smooth slide. Species, too, could have zones of erratic mixing but still overall be defined as species.
Read the full story here.