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Regulation of the Lactase Gene

Lactose Intolerance and Gene Regulation

Do you know someone who is lactose intolerant? What causes lactose tolerance and intolerance?

It turns out that lactose tolerance is a fascinating example of how humans evolved a new trait to take advantage of a new food source. It resulted from a change in the way a gene is regulated.

A two-paneled illustration of a baby labeled lactose tolerant and a young man labeled lactose intolerant.
A two-paneled illustration: on the left is a baby and a container of milk labeled lactose tolerant can digest milk, on the right is a young man and a crossed-out milk container labeled lactose intolerant can't digest milk.