Which statement explains why humans do not have distinctly different genetic makeups along racial lines?

Which statement explains why humans do not have distinctly different genetic makeups along racial lines?

• A. All humans lived in the same region until relatively recently in evolutionary time.
• B. Humans migrated long distances and developed distinct gene pools.
• C. Genetic differences across populations are vast and clear.
• D. Race is a fixed biological category.

Answer: (A)

The main idea is that human genetic variation is not organized into clear, separate racial groups because populations have shared ancestry and extensive mixing over time. If all humans lived in the same region until relatively recently, there hasn’t been enough time for completely separate gene pools to form. Once people began moving and intermarrying, gene flow spread genetic material widely, so differences among groups remain small and gradual rather than large and discrete. That makes it unlikely to find distinctly different genetic makeups that line up with racial categories. The other statements imply more lasting isolation or rigid boundaries that don’t fit how human genetics actually works: long migrations creating strong, separate gene pools would produce noticeable separation, but that isn’t what the data show; genetic differences between populations aren’t vast and obvious, since most variation exists within populations; and race isn’t a fixed biological category, because genetic boundaries aren’t clean or universally consistent.

The main idea is that human genetic variation is not organized into clear, separate racial groups because populations have shared ancestry and extensive mixing over time. If all humans lived in the same region until relatively recently, there hasn’t been enough time for completely separate gene pools to form. Once people began moving and intermarrying, gene flow spread genetic material widely, so differences among groups remain small and gradual rather than large and discrete. That makes it unlikely to find distinctly different genetic makeups that line up with racial categories.

The other statements imply more lasting isolation or rigid boundaries that don’t fit how human genetics actually works: long migrations creating strong, separate gene pools would produce noticeable separation, but that isn’t what the data show; genetic differences between populations aren’t vast and obvious, since most variation exists within populations; and race isn’t a fixed biological category, because genetic boundaries aren’t clean or universally consistent.