What is one effect of natural selection in human populations today?

Natural selection in human populations today plays a crucial role in the survival and propagation of traits that enhance adaptability to changing environments and varying challenges. This process favors individuals with advantageous traits that improve their chances of survival and reproduction in their specific environments.

For example, traits related to resistance to certain diseases or the ability to thrive in diverse climates can be selected for in populations that encounter these challenges. As environments continue to change — whether due to climate shifts, urbanization, or exposure to new pathogens — the traits that confer an advantage can become more prevalent in successive generations. This ongoing process illustrates how human populations are still subject to natural selection, shaping their evolution in response to contemporary conditions.

In contrast, other choices do not accurately reflect the positive and adaptive nature of natural selection. Reduction in genetic diversity is a potential outcome of other factors, such as habitat loss or bottlenecks, rather than a direct effect of natural selection. Increased vulnerability to disease does not specifically result from natural selection but can be influenced by numerous factors including changes in lifestyle and environment. Stagnation in evolutionary progress overlooks the dynamic nature of evolution, which is continually shaped by various selective pressures impacting human populations.