Natural selection independently produced five distinct lactase-persistence mutations across herding populations

Evidence

It appears that as herding animals became a centerpiece of economies around Eurasia and Africa, natural selection independently found five different genetic variants to suppress the shutdown of lactase production in different populations. In Europe, there was a flip on chromosome 2 just a short distance upstream from the gene that codes for the protein lactase (LCT ). The DNA base cytosine got swapped for thymine. This flip may simply have thrown a monkey wrench into the otherwise mammalian standard “off switch” for the making of lactase proteins after weaning. Elsewhere, in Africa and the Middle East, the DNA swaps are different, though they are all between 13,000 and 15,000 bases upstream from LCT . — Joseph Henrich, The Secret of Our Success, 299

Categorization

• XREF: Confirms a parallel evolutionary story to the cultural-fitness landscape idea: same adaptive pressure, distinct genetic solutions. Relevant context for how local adaptations (herding packages) drove selection. — connects to: Milking created selection pressure that extended lactose processing past infancy. — Joseph Henrich, The Secret of Our Success: How Culture…, 295; Lactase persistence varies dramatically even among neighboring African ethnic groups. — Joseph Henrich, The Secret of Our Success: How Culture…, 294; Adopting cheese technology can halt a population’s lactase gene evolution — Joseph Henrich, The Secret of Our Success: How Culture…, 295 (+1 more)

Broader Connections

• Adopting cheese technology can halt a population’s lactase gene evolution #expands (0.82) — Joseph Henrich, The Secret of Our Success, 295
• Replicated divergent selection populations rule out chance in evolution experiments #exemplifies (0.78) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 293