First, it is consistent with what we know about the timeline of lactose tolerance evolution in Europe.

The genetic variant that confers adult lactase persistence — known as LP — spread through European populations during the Bronze Age, roughly 3,000 to 4,000 years ago, well after Cheddar Man’s time.

Its current high frequency in northern European populations is the result of strong natural selection during that period, in communities that depended heavily on domesticated cattle for their food supply and whose survival and reproductive success was substantially enhanced by the ability to digest milk throughout life.

In the Mesolithic, when dairy farming did not exist, there was no selection pressure for lactase persistence.