Evolution

What is evolution?

The gradual change of organisms over a long time, producing new species.

Evidence

• Fossil records: show changes over time (e.g. the horse).
• Comparative anatomy:
• Homologous structures: same basic structure, different functions (the pentadactyl limb in humans, bats, whales). Shows divergent evolution.
• Analogous structures: different structures, same function (wings of birds and insects). Shows convergent evolution.
• Vestigial structures: reduced, no clear use (human appendix, coccyx).
• Comparative embryology: similar early embryos.
• Cell biology: similar organelles and DNA in all organisms.
• Geographical distribution: e.g. marsupials in Australia.