Lactase persistence varies dramatically even among neighboring African ethnic groups.

Evidence

In Africa, the patterns are strikingly patchy. Some groups have high frequencies of lactase persistence whereas neighboring groups do not. In the Sudan alone, rates range from around 20% up to 90%, depending on the ethnic group. In East Asia, lactase persistence is rare and often nonexistent. — Joseph Henrich, The Secret of Our Success, 294

Categorization

• XREF: connects to: Milking created selection pressure that extended lactose processing past infancy. — Joseph Henrich, The Secret of Our Success: How Culture…, 295; Culture-fueled lactose persistence spread to a third of humanity in ten millennia — Joseph Henrich, The Secret of Our Success: How Culture…, 299; Natural selection independently produced five distinct lactase-persistence mutations across herding populations — Joseph Henrich, The Secret of Our Success: How Culture…, 299 (+2 more)

Broader Connections

• Cultural economic packages drive genetic differences even between nearby populations #expands (0.85) — Joseph Henrich, The Secret of Our Success, 311
• Natural selection independently produced five distinct lactase-persistence mutations across herding populations #corroborates (0.80) — Joseph Henrich, The Secret of Our Success, 299
• Culture-fueled lactose persistence spread to a third of humanity in ten millennia #expands (0.78) — Joseph Henrich, The Secret of Our Success, 299
• Civilizations divide into sweet-milk, sour-milk, and no-milk zones #qualifies (0.72) — Bernard Lewis, From Babel to Dragomans, 239