What is it about?
This paper presents a comprehensive study on the evolutionary origins of lactase persistence (LP) in East Asian populations, challenging conventional understanding. Key findings include: (1) Neanderthal Introgression: The East Asian-specific lactase gene (LCT) enhancer haplotype originated from Neanderthal DNA, with 75–96% allele matches to Neanderthal genomes. This archaic introgression occurred ~25,000–28,000 years ago, predating dairy domestication. (2) Immune Adaptation Over Lactase Persistence: Unlike Europeans, where LP evolved alongside dairy consumption, the East Asian haplotype shows no LP-associated alleles. Instead, it regulates immune-related genes (UBXN4, DARS1, DARS1-AS1), influencing neutrophil counts and stress responses. Selection likely responded to Last Glacial Maximum environmental stresses rather than dietary shifts. (3) Multifunctional Genomic Effects: The 2q21.3 locus exhibits pleiotropy, affecting both lactase expression in immune cells and immune adaptation. Tissue-specific regulation diverges from European LP patterns, emphasizing distinct evolutionary drivers. (4) Methodological Insights: The study integrates ancient DNA analysis, haplotype networks, and selection detection tools such as ArchaicSeeker 2.0, PBS, to trace archaic origins and adaptive benefits. Results highlight the role of Neanderthal admixture in providing pre-adapted genetic variants. (5) Evolutionary Implications: The findings redefine LP as a secondary effect in East Asians, illustrating how population-specific pressures (pathogens, climate) and archaic introgression shape adaptation. This challenges gene-culture coevolution narratives centered on dairy use. The work suggests East Asian lactase gene evolution was driven by immune resilience during climatic upheaval, offering a paradigm shift in understanding human evolutionary trajectories.
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Why is it important?
This study reshapes our understanding of human adaptation by revealing how East Asian lactase persistence—a Neanderthal DNA gift from Ice Age survival—evolved not for dairy, but as a genomic multitool. We show this 40,000-year-old haplotype, carried by 60% of East Asians today, was repurposed to boost immune defenses against ancient pathogens and famine. Unlike Europeans’ diet-driven evolution, we decode a "genetic Swiss Army knife" effect where the same DNA region controls both lactase and immune cells like neutrophils. By blending Ice Age genomes, AI-driven introgression mapping, and single-cell genomics, we bridge ancient hybridization events to modern health disparities, offering an evolutionary lens for East Asian-specific immune disorders. This work revolutionizes the textbook gene-culture narrative, proving that some human adaptations are accidental time travelers—Neanderthal DNA fragments that solved Pleistocene crises now echo in our milk tolerance and disease risks. It’s not just about lactase; it’s a DNA palimpsest where survival, archaic love affairs, and immune battles converge, rewriting how we view human-Neanderthal legacies while inviting broader audiences to see evolution as a layered, unpredictable drama.
Perspectives
I hope this exploration transforms how we perceive lactase persistence—from a narrow "textbook" trait to a riveting saga of human survival. This Neanderthal DNA fragment in East Asians isn’t just about digesting milk; it’s a time capsule revealing how immune battles and ice age extremes shaped our bodies in ways we’re only beginning to decode. When you sip a latte or face an infection, you’re interacting with evolutionary echoes of ice age clans and archaic hominins. More than genes and data tables, this story connects us all to humanity’s shared improvisation against starvation, pathogens, and a changing planet. If nothing else, let it spark wonder at how deeply our past lives within us—and how much we still don’t know.
Shuhua Xu
Fudan University
Read the Original
This page is a summary of: Neanderthal adaptive introgression shaped
LCT
enhancer region diversity without linking to lactase persistence in East Asian populations, Proceedings of the National Academy of Sciences, March 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2404393122.
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Resources
Lactase and the Neandertals
New research shows that a common gene variant that may explain some lactase persistence in East Asia is introgressed from Neandertals.
East Asian human gene that allows adult humans to digest sugars in milk likely came from Neanderthals
A small team of computational and evolutionary biologists from the University of Chinese Academy of Sciences, Zhongshan Hospital and the Max Planck Institute for Evolutionary Anthropology, reports that unique lactase genes carried by about 25% of East Asian people may have been inherited from Neanderthals.
Milk genes Neanderthals? New study reveals a surprising ancestral twist
About 25% of East Asians carry unique lactase ... Far from being useless, these ancient lactase genes may have offered survival benefits, showing Neanderthal DNA is more than a relic.
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