Evolutionary theory is supported by several lines of evidence, among which three key types stand out: fossil records, comparative anatomy, and molecular biology.
1. Fossil Records
The fossil record serves as a historical archive of life on Earth. It provides snapshots of ancient organisms, showing progression and change over millions of years. By studying the sequence and characteristics of fossils found in different geological layers, scientists can trace the evolutionary history of various species. For instance, the transition from fish to amphibians can be observed in fossils that display features of both groups.
2. Comparative Anatomy
Comparative anatomy examines the similarities and differences in the structures of different organisms. The presence of homologous structures—body parts that are structurally similar due to shared ancestry—strongly supports evolution. For example, the forelimbs of humans, whales, and bats have different functions but share a similar bone structure, indicating they evolved from a common ancestor. This evidence highlights how species adapt to different environments while maintaining basic structural traits.
3. Molecular Biology
Molecular biology involves the study of the genetic and biochemical makeup of organisms. DNA sequencing has unveiled significant genetic similarities between diverse species. For example, humans share about 98% of their DNA with chimpanzees, indicating a close evolutionary relationship. Additionally, the presence of similar genetic markers in various organisms suggests common ancestry and the gradual divergence of species over time.
In conclusion, fossil records, comparative anatomy, and molecular biology provide robust evidence supporting the theory of evolution, illustrating how life has evolved and diversified on our planet.