Neutral theory of molecular evolution

Neutral Theory of Molecular Evolution is a theory that says that many changes in DNA (the genetic material inside all living things) happen randomly and are not caused by natural selection. It states that little differences in DNA that are not harmful to living things (called "neutral" changes) happen randomly and will spread throughout a species over time. Some of these neutral changes can be passed down from parent to offspring, so organisms become slightly different from each other and from their ancestors. This process helps to explain why we see differences between species, even though they often look alike.