You have considered the human trait of the ability to digest milk after infancy in the PowerPoint slides, one of the required readings and the short film "Got Lactase?"
The ability to digest milk as an added food source for Neolithic humans was likely to be extremely beneficial in Neolithic human's reproductive success.
Given the potential benefit of lactase (enzyme) persistence in humans, what are your thoughts about the length of time needed for natural selection to act for spread the possession of the gene(s) for lactase persistence in the populations described in the assigned sources?
Does the amount of human variability in the ability to digest lactose after infancy surprise you? Why or why not?