Final answer:
To understand why a particular trait is common in a population, we should study how that trait affects the genetic basis of population-wide traits.
Step-by-step explanation:
If we want to understand why a particular trait is common in a particular population, we should study how that trait: affects the genetic basis of the population-wide traits.
Studying how a trait affects the genetic basis of population-wide traits involves analyzing the genetic makeup of individuals in the population and tracking changes in allele frequencies over time. This can provide insights into the selective forces that may be operating on the population and contribute to the prevalence of the trait.