Evidence for Evolution

Types of Evidence

  • The Fossil Record gives us an indication of the animals that lived on Earth in the past. It helps to show how organisms have evolved and become incredibly complex over time. It also allows scientists to track the path of evolution for humans.
  • Comparative Anatomy involves comparing the structural features of different species or groups of animals.
    • For example, the forearms of mammals, amphibians, reptiles and birds are very similar in structure.
  • Analogous Structures are not similar to homologous structures as it talks about unrelated species that are living in similar environments (with similar selection pressures) in different parts of the world which have similar structures.
    • For example, the fins of a dolphin and a shark are analogous structures as they perform the same role but have different evolutionary origins.
  • Comparative Embryology involves organisms that go through similar stages of embryonic development and they are believed to be closely related. In the early stages of development the embryos of humans and other animals look very similar.
    • For example, the embryos of fish, amphibians, reptiles, birds and mammals all initially have gill slits but as the embryos develop further, the gill slits disappear in all but fish.It is thought that gill slits were a characteristic that all these animals once shared with a common ancestor
  • Biogeography is the study fo the distribution of species to help make links to their evolution. This particularly involves the fact that all the continents were once whole in what is known as Pangea.
  • Molecular biology is the study of the evolutionary relationships reflected in DNA and proteins.The closer the match in the DNA sequences, the more recent their common ancestor and hence the more closely they are related. DNA hybridisation is a technique that can be used to compare the DNA in different species to determine how closely related they are
    • For example, humans and chimpanzees have very similar DNA, compared to that of humans and ferns.