Question

Lactase deficiency is more common in Asian, Native American, Mediterranean and some African populations than it is among people with northern or western European ancestry. How would you explain why this is so? a. Asian, Native American, Mediterranean, and some African populations suffer from lactase deficiency because they have low levels of lactose in their diet. b. Although most mammals, including humans, are able to digest the milk sugar, lactose, after infancy, Asian, Native American, Mediterranean, and some African populations lost this ability through mutations about 7000 years ago. c. Asian, Native American, Mediterranean, and some African populations suffer from lactase deficiency because they have high levels of lactose in their diet. d. Although most mammals, including humans, are not able to digest the milk sugar, lactose, after infancy, the ancestors of northern and western Europeans relied on dairy products as an important part of their food supply. e. When other food sources were in low supply, mutations that allowed the expression of the enzyme lactase to persist past childhood conveyed an advantage to adults who were able to include dairy products in their diet.

Answer 1

The correct answers are:

d. Although most mammals, including humans, are not able to digest the milk sugar, lactose, after infancy, the ancestors of northern and western Europeans relied on dairy products as an important part of their food supply;

e. When other food sources were in low supply, mutations that allowed the expression of the enzyme lactase to persist past childhood conveyed an advantage to adults who were able to include dairy products in their diet.;

The humans from Northern and Western Europe, unlike the other people, lived in conditions where very often the food sources were scarce. With the domestication of the animals, especially the cows, goats, and sheep, the humans in this regions started to use the milk from these animals in times of crises. Over time their organisms started to become more prone to digesting the milk, thus having less and less problems with the lactose. Also, the people who were able to tolerate the dairy diet were seen as having advantageous traits, thus became more favorable for mating, which gradually increased and made dominant the population that is able to have dairy diet.