AP BIOLOGY

Detailed explanation-1: -He argued that natural selection explained how a wide variety of life forms developed over time from a single common ancestor. Darwin did not know that genes existed, but he could see that many traits are heritable-passed from parents to offspring.

Detailed explanation-2: -The mechanism that Darwin proposed for evolution is natural selection. Because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations.

Detailed explanation-3: -However, the theory of evolution tells us nothing about how the first life formed: it only tells us how and why existing life changes.