Gene-culture coevolution

Gene-culture coevolution is the study of how genetic and cultural processes interact across evolutionary time — not as separate streams that occasionally intersect, but as a single coupled system in which each channel modifies the selective pressures acting on the other. Humans do not merely evolve biologically and then invent culture on top; they evolve biologically \u003cbecause\u003e they have culture, and their culture evolves \u003cbecause\u003e of the biological capacities that make it possible.

The canonical example is lactase persistence: the genetic capacity to digest milk into adulthood evolved in populations with a history of dairy farming, and dairy farming spread most rapidly in populations where the mutation was already present. Neither the gene nor the practice drove the other alone; they co-constructed each other. This is not simply an instance of \u003cb\u003enatural selection\u003c/b\u003e acting on a culturally modified environment. It is a feedback loop in which the cultural practice changes the genetic landscape and the genetic landscape changes which cultural practices are viable.

The field draws on theoretical frameworks from population genetics, archaeology, and \u003cb\u003ecultural evolution\u003c/b\u003e, but its most distinctive feature is the insistence on formal modeling. Gene-culture coevolutionary models typically track two inheritance systems — genetic and cultural — and compute how their coupled dynamics produce outcomes that neither system could produce alone. The mathematics is borrowed from epidemiology and \u003cb\u003epopulation genetics\u003c/b\u003e, but the interpretation requires taking culture seriously as an evolutionary system in its own right.

Critics argue that the models are too simple to capture real cultural dynamics, which involve horizontal transmission, prestige bias, and conformist learning in ways that resist population-genetic formalization. Proponents reply that simplicity is the point: the models are existence proofs, not predictions, demonstrating that gene-culture interaction is not merely plausible but mathematically inevitable under plausible assumptions.

The deepest question gene-culture coevolution raises is whether culture is even the right unit of analysis. If genes and culture are inseparable, then treating them as two systems in interaction may itself be a residue of the dualism that the field is trying to overcome. Perhaps what evolves is not a genome plus a meme pool but a single \u003cb\u003eniche-constructing\u003c/b\u003e lineage in which informational and chemical inheritance are merely two aspects of one process.