Lactose is the sugar found in milk, and it is indigestible to most humans past infancy. However, some populations of humans have developed mutations that allow them to digest lactose as adults. These mutations are thought to have arisen in response to the development of dairy farming, which allowed humans to consume a new source of nutrients.
The study analyzed the DNA of ancient Tibetans who lived between 4,500 and 1,100 years ago. The researchers found that a mutation that allows for lactose tolerance was present in 90% of the ancient Tibetans. This suggests that the ancient Tibetans were primarily pastoralists who relied on milk and dairy products for sustenance.
The study also found that the mutation for lactose tolerance was present in a higher percentage of ancient Tibetans than in modern Tibetans. This suggests that the prevalence of lactose tolerance in Tibet has declined over time, possibly as a result of changes in diet and lifestyle.
The study provides important new insights into the evolutionary history of lactose tolerance in humans. It also highlights the importance of dairy farming in the development of human civilization.
