Final answer:
The idea that individuals within a population evolve is false; evolution occurs at the population level and is driven by changes in genetic composition over time. Individual organisms develop but do not evolve; evolution is reflected in the shifting traits within a population due to various evolutionary processes like natural selection.
Step-by-step explanation:
The statement that populations evolve over time because the individuals that form them are individually evolving is false. An individual cannot evolve; their genetic makeup does not change over time. Evolution refers to the change in the genetic composition of a population over time, driven by differential reproduction based on certain alleles. Rather than individual evolution, development occurs within an individual's lifespan, influenced by their genes and environment. Evolutionary changes are reflected in the population as a whole, not in single individuals.
For example, in a population of finches, natural selection might favor birds with larger bills, leading to a bigger average bill size in the population over generations. This change is not due to the birds' individual bills growing or changing during their lifetimes, but to the greater reproductive success of those with larger bills, eventually shifting the population's average bill size as those birds pass their genes on to offspring.
Evolution happens on a population level through processes such as natural selection, migration, genetic drift, and mutation. Population genetics is the branch of science that studies these changes within populations over time.