India is one of the highest consumer of milk and milk products. India’s milk output is expected to expand at the fastest rate in the world. The OECD prejects it at 3.6% annually, between 2025 and 2034. Dairy is fundamental to everyday life, from temple gifts to morning chai. However, the majority of adult Indians are unable to effectively digest fresh milk. This discrepancy and its implications for India’s distinct evolutionary history are explained by new genomic studies. This is explained by a comprehensive genome-wide analysis conducted by the University of California, Berkeley. According to the study, lactose intolerance is common in India. It is widespread in biology.
Lactose Intolerance Is the Global Norm#
During infancy, humans create an enzyme known as lactase. The sugar in milk, lactose, is broken down by lactase. Lactase synthesis typically decreases with age.
Approximately 70% of people worldwide suffer from some form of lactase insufficiency. Because of this, the capacity to digest milk as an adult is a rare characteristic. Bangladesh, Pakistan, and India are all well within this majority. The majority of South Asian people do not produce enough lactase to safely digest fresh milk, even though they consume a lot of dairy products. After consuming milk, this causes bloating, stomach pain, and digestive distress.
The Milk-Digesting Gene Exists, But Rarely#
Researchers have connected a genetic variation close to the lactase gene to adult milk digestion. -13910*T is the name of this variation. Long into adulthood, people with this gene continue to produce lactase. According to research, this mutation first appeared in pastoralist communities in what is now western Russia around 5,000 years ago. This gene expanded widely throughout Europe. It didn’t in South Asia.
Under the direction of biologist Priya Moorjani, the Berkeley-based team examined genetic information from over 8,000 people. This comprised samples from 3300 BCE to 1650 CE, as well as contemporary DNA. The locations of the -13910*T allele throughout the Indian subcontinent were mapped by the researchers. To determine the gene’s origin, they also compared nearby DNA fragments. There was a distinct pattern in the results.
Two Communities Defy the Trend#
There are two groups that are distinct from the rest of South Asia. The Gujjar community in Pakistan and the Toda community in Tamil Nadu’s Nilgiri Hills exhibit exceptionally high lactose tolerance. As adults, almost 90% of members of these tribes are able to digest fresh milk. One important characteristic unites both societies. They have historically relied on the herding of buffalo. A significant portion of their daily diet consists of fresh milk. For them, nutrition and survival are strongly impacted by their capacity to digest milk.
In these populations, natural selection had a powerful effect. Researchers discovered that these groups have some of the strongest selection pressure for the milk-digesting gene in recent human evolution.
Migration Shaped the Genome#
The study identified pastoralists from the Eurasian Steppe as the source of the milk-digesting gene in South Asia. During the historical and medieval eras, these populations arrived to the subcontinent. Their genetic signature is quite similar to that of South Asian bearers of the mutation -13910*T. The gene did not proliferate despite this introduction. Its limited reach could hardly be explained by chance alone, according to genetic simulations. Cultural customs were more important.
India Solved Milk Digestion Without Genetics#
Indian food traditions reduced the need for genetic adaptation. Fermentation lowers lactose content. Curd, ghee, buttermilk, paneer, and lassi dominate Indian diets. These foods remain easier to digest even for people with low lactase levels. Boiling milk, diluting it, or consuming it with grains and spices also reduces digestive stress. These practices allowed dairy consumption without requiring widespread lactose tolerance. As a result, natural selection never pushed the milk-digesting gene into the broader population.
Rethinking Milk and Health in India#
The way Indians perceive milk intolerance has been reframed by this study. Digesting fresh milk is not a sign of weakness or a contemporary issue. It depicts typical human biology that has been influenced by culture and history. It also explains why many Indians choose lactose-free or fermented dairy products. The body reacts as it has been trained to by evolution. Anthropologists today contend that there is much more to learn about milk digestion worldwide. Rich dairy cultures can be developed by human populations without genetic modification, as demonstrated by South Asia.
A Mosaic of Genes and Culture#
The study concludes that lactase persistence does not follow a single global pattern. In some regions, genes adapted. In others, culture adapted instead. India represents the latter path. The genome reflects migration, diet, and daily practice. Together, they shaped how Indians consume milk today. India’s dairy story proves that evolution works in more than one way. Sometimes, culture leads. Genetics follows only when needed.
Clear Cut Health Desk
New Delhi, UPDATED: Jan 05, 2026 12:48 IST
Written By: Nidhi Chandrikapure
