Did Farming Make Us Smarter? The Rice-and-Wheat Test

Farming was a revolution in time. Foragers also planned ahead, but agriculture tied survival to a longer and less forgiving calendar. Seed disappeared into the ground months before food came out. Storage, irrigation, inheritance and the coordination of labor turned patience and planning into material assets.

It also created crowded settlements, unfamiliar diets, new disease environments and much larger populations. In The 10,000 Year Explosion, Gregory Cochran and Henry Harpending argued that this upheaval accelerated human evolution. Culture had not replaced natural selection; it had built a new arena for it. Hawks and colleagues later reported genomic patterns consistent with unusually rapid adaptation during the Late Pleistocene and Holocene.

The cognitive version of that argument is straightforward. If farming societies rewarded learning, planning and sustained effort, variants associated today with educational attainment might have increased. If they rewarded a greater willingness to wait for future rewards, variants associated with delay discounting might have decreased.

This is the East Asian test. The genome collection used here is centered on East Asia, where rice and wheat can be matched to local archaeological adoption dates. Europe, Africa and the Americas each require their own agricultural clock, built from their own crops, archaeological sites and ancient genomes. They are the natural next tests.

This is the first direct test of the farming hypothesis with ancient DNA. Previous studies tracked genetic change over calendar time or compared broad archaeological groups. Here, the date of local crop adoption enters the model itself, making it possible to ask whether the genetic trajectory changes when farming arrives.

Ancient DNA had already revealed half the story

Piffer and Kirkegaard found rising educational-attainment and IQ polygenic scores across European genomes spanning roughly 12,000 years. Akbari and colleagues found evidence of directional selection across West Eurasia and higher mean scores among early European farmers than Western hunter-gatherers.

These studies make a Holocene rise plausible, but farming itself remains in the background: calendar time and broad archaeological labels stand in for the event. The innovation here is to synchronize every genome to its own local farming transition. Each person is placed on an agricultural clock—centuries before or after the first local evidence of domesticated crops—so the analysis can ask whether the genetic trajectory actually bends when farming arrives.