Final answer:
Differences among different human populations have emerged through natural and sexual selection, leading to specific traits and observable variations. Natural selection favors individuals with certain traits that enhance their survival and reproductive success, while sexual selection leads to distinct phenotypic differences between males and females. The spread of humankind across the globe has also contributed to genetic differences among populations.
Step-by-step explanation:
How differences among different human populations arose by natural and sexual selection:
Differences among different human populations have emerged through natural and sexual selection. Natural selection occurs when individuals with certain traits are more likely to survive and reproduce, passing on their genes to the next generation. This can lead to the spread of specific traits within a population. Sexual selection, on the other hand, occurs when one sex has more reproductive success than the other, resulting in distinct phenotypic differences between males and females. For example, male birds often have more colorful plumage than females. The spread of humankind across the globe has also contributed to the genetic differences among populations, resulting in observable variations in stature, facial features, and skin color.