One line of evidence supporting evolution that scientists have learned about since Darwin published "On the Origin of Species" is the discovery of ancient DNA. This has allowed scientists to directly compare the genetic sequences of extinct species to those of living organisms, providing a powerful tool for understanding evolutionary relationships and the process of natural selection.

Before the development of ancient DNA techniques, scientists relied heavily on the fossil record and anatomical comparisons to reconstruct evolutionary lineages. While these methods provided valuable insights, they were limited in their ability to directly trace genetic changes over time. Ancient DNA, however, allows scientists to literally look back in time at the genetic code of ancient organisms. This has yielded groundbreaking discoveries, such as the identification of the genetic basis for Neanderthal traits and the evolutionary history of extinct species like mammoths.

The ability to study ancient DNA has provided a wealth of new data that supports Darwin's theory of evolution by natural selection and has revolutionized our understanding of the history of life on Earth.