Answer: Lactase persistence is more prevalent in indigenous populations of humans in northern Europe and parts of Africa than in other regions of the world due to natural selection. In these regions, where dairy farming was a significant part of the local economy and diet, individuals who could digest lactose throughout their lives had a survival advantage over those who couldn't. Over time, the frequency of lactase persistence alleles increased in these populations. This demonstrates how the environment and the pressures it imposes can drive the evolution of traits in a population over time.
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