Evidence for Evolution

Evolution is supported by an overwhelming body of evidence from multiple independent fields of biology. At A-Level, you need to understand and evaluate the different lines of evidence in detail, including the fossil record, comparative anatomy, molecular biology, biogeography, and direct observation.

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The Fossil Record

What the Fossil Record Shows

The fossil record provides direct physical evidence of organisms that lived in the past. It demonstrates:

1. Life has changed over time — ancient fossils differ from modern organisms
2. Transitional forms exist — fossils showing intermediate features between major groups
3. Extinction is real — many species that once existed are no longer alive
4. Sequential appearance — simpler organisms appear in older rocks; more complex organisms appear in younger rocks
5. Biogeographical patterns — fossil distributions match predicted evolutionary relationships

Transitional Fossils

Transitional fossils (or "intermediate forms") show features of two different groups, providing evidence that one group evolved from another.