East Asians started drinking milk before raising animals.

Lactose in Milk and Its Role in Nutrition

• Female mammals produce milk to nourish their young, which is primarily made from lactose.

• The breakdown of lactose into simpler sugars, glucose, and galactose is mediated by an enzyme called lactase.

• After weaning, babies lose the ability to produce lactase, leading to symptoms like bloating, flatulence, and diarrhea.

Lactose Persistence in Adults

• Despite the effects of lactose intolerance, millions of people worldwide continue to consume dairy products due to genetic mutations that allow them to continue producing lactase as adults.

• The mutations that confer lactase persistence emerged independently in different populations, particularly in North European and African populations.

Research Findings

• Researchers from Fudan University, the Max Planck Institute for Evolutionary Anthropology, and the Université de Lyon found a distinct evolutionary pathway for lactase persistence in East Asian populations.

• The East Asian lactase persistence gene had come from the Neanderthals, an archaic group of humans that went extinct about 30,000 years ago.

• Evidence of pre-agricultural selection pressures began more than 30,000 years ago, suggesting that the East Asian genomes began evolving towards lactase persistence several millennia before these populations began to domesticate livestock.

Neanderthals in Our Genome

• About 7 million years ago, the evolutionary line leading to the contemporary Homo sapiens diverged from the one leading to our closest living cousins, the chimpanzees and bonobos.

• About 800,000 years ago, our line split again: one population broke away and migrated to Eurasia, adapting to cold climes and eventually becoming the Neanderthals.

• Today, about 1-4% of the genome of individuals with Eurasian ancestry represents Neanderthal-derived DNA sequences.

DNA Sequences and Selection

• Neanderthal skeletal remains have yielded DNA, which scientists can distinguish from those of modern humans.

• There are about 9.6 million points of difference between Neanderthal and human DNA sequences, in terms of the bases the DNA is made of.

• The Allen Ancient DNA Resource (AADR) found one modern human who lived around 14,000 years ago in the Amur area of China who carried the Neanderthal-derived lactase gene.