Final answer:
The allele that allows humans to continue to produce lactase throughout their lives contributes to lactase persistence, an evolutionary adaptation in populations with dairy-rich diets. Carriers can pass on this mutant allele to their offspring, and it is understood to be a key factor influencing the ability to digest milk into adulthood.
Step-by-step explanation:
The allele responsible for allowing humans to continue producing lactase throughout their lives is associated with lactase persistence, an adaptation which has evolved in populations with a long history of dairy consumption. This genetic variation has been a significant factor in human evolution, as it influenced the ability to consume milk into adulthood. Carriers of this mutant allele can pass it on to their offspring, potentially providing a survival advantage in environments where dairy is a key nutritional resource.
In humans, the ability to process lactose beyond infancy is due to variations in the regulation of the lactase gene. This continued expression of lactase allows for the digestion of lactose, the sugar found in milk, preventing lactose intolerance. The gene that controls this trait is different from the lac operon in bacteria, which also deals with lactose metabolism, but does involve similar concepts such as the production of enzymes like beta-galactosidase that break down lactose into glucose and galactose.
Understanding the genetic basis of traits like lactase persistence is crucial in the field of genetics and can have implications in areas like nutrition and anthropology, where the origins and spread of dairy agriculture are studied.