Science Quote by Peter R. Grant

In a single, tidy sentence, Peter R. Grant smuggles an entire worldview about evolution: nature changes, but it does so under the constant pressure of connection. “Exchange of breeding individuals” is clinical phrasing that makes migration sound like bookkeeping, yet the implication is volatile. Movement is not just travel; it is genetic influence. The line’s specific intent is to name gene flow as evolution’s great blender, the force that pulls populations back toward similarity even as selection, drift, and isolation try to pry them apart.

The subtext is almost political. Two populations can start to look like separate “communities,” but if enough individuals cross the boundary and reproduce, the boundary stops mattering at the genetic level. “Tends to” is the scientist’s humility and the scientist’s knife: it acknowledges exceptions (strong local selection, limited mating, hybrid infertility) while still asserting a directional truth. Homogenization is framed as a tendency, not a destiny, which is precisely how population genetics thinks: in probabilities, not parables.

Context matters here because Grant is inseparable from real-world examples of evolution in motion, especially the Galapagos finches he and Rosemary Grant studied. On islands, a little migration can either rescue genetic diversity or erase emerging differences. The sentence functions like a warning label against simplistic stories of speciation: divergence requires not just different pressures, but the throttling of contact. It’s a reminder that evolution isn’t only about who survives; it’s about who meets, who mates, and how porous the map really is.