How does natural selection drive evolution?

• A. Evolution occurs only through genetic drift.
• B. Traits that help survival are passed down, changing the population over time.
• C. All individuals acquire traits during their lifetime.
• D. Species interbreed to form new species immediately.

Answer: (B)

Natural selection drives evolution by changing which traits become more common in a population. In every generation, individuals vary in heritable traits, and those features that help with finding food, avoiding predators, or attracting mates tend to leave more offspring. Because these advantageous traits are inherited, they increase in frequency over generations, reshaping the population and leading to adaptation to the environment. This view emphasizes that evolution is about shifts in allele frequencies across generations, not about individuals acquiring new traits during their lifetimes. It also clarifies that random genetic drift and immediate, dramatic species formation from interbreeding don’t capture how natural selection builds populations over time.