Question

Lactase persistence in European and east African human populations evolved ____________________________________________ in the two lineages.

a. independently

b. a single time

c. due to genetic drift

d. at the same time as bipedalism

Answer 1

Answer: a. Independently

Explanation: The above is an example of convergent evolution. In this type of evolution the occurs independent evolution of similar features in different species at different times. Lactose cannot be broken down, hence it can't be used as the source of energy. But instead lactose broken down to glucose and galactose can be easily utilized as an energy source.

- Lactase persistence is the activity/process of humans to produce lactase even in adulthood. Lactase persistence is rare in Africa and highest in northern Europe. Even though it is present in both groups they don't have the same genetic basis. Hence it can be said that they have arisen independently.

- It is based on the introduction of cattle domestication in both groups. It occured some 5000 years ago in Africa and some 8500 years ago in Europe. So, the timing and the gene expression level make the evolution independent.

Incorrect answers:

- single time: According to a research the European mutation originated some 8,000-10,000 years ago and African mutation some 3000-7000 years ago.

- Due to genetic drift: Genetic drift is a change in the allelic frequency of the population. The above example is of convergent evolution.

- at the same time as bidedalsim: It has nothing to do with bipedalism and locomotion.