1. Fossil Record: Fossils found in different layers of rock provide a historical record of life on Earth. Older layers contain fossils of simpler organisms, while newer layers show more complex organisms. This gradual change in fossils over time strongly suggests that life has evolved.
2. Comparative Anatomy: Comparing the anatomy of different species reveals similarities that point to common ancestry. For example, the skeletal structures of a human arm, a bat wing, and a whale flipper are remarkably similar, despite their different functions. These homologous structures suggest that these organisms share a common ancestor.
3. DNA and Genetic Evidence: The genetic code (DNA) is a blueprint for life. Comparing the DNA sequences of different organisms can show how closely related they are. For example, humans and chimpanzees share around 98% of their DNA, indicating a recent common ancestor. The closer the genetic similarity, the more recent the shared ancestor.
