Evidence for evolutionSpec 4.6.3.4
In short
The evidence for evolution by natural selection comes from three main sources. It has been shown that characteristics are passed on to offspring in genes. The fossil record shows how organisms have changed over time. Antibiotic resistance in bacteria shows natural selection happening in a short time. This evidence is why the theory is now widely accepted.
The theory of evolution by natural selection is now widely accepted. Evidence for Darwin's theory is now available. You need to be able to describe the evidence, including fossils and antibiotic resistance in bacteria.
- It has been shown that characteristics are passed on to offspring in genes.
- The fossil record provides further evidence (see the next section).
- Knowledge of how resistance to antibiotics evolves in bacteria provides evidence that natural selection happens and can be seen in a short time (see Resistant bacteria).
Exam tip:Link your evidence to the theory. Say what is seen (for example fossils show how organisms have changed), then say how it supports evolution by natural selection.
Written and checked against the AQA GCSE Combined Science (8464) specification · Updated October 2026
Frequently asked questions
What is the evidence for evolution?
The evidence for evolution includes the fossil record, which shows how much or how little organisms have changed as life developed on Earth, the discovery that characteristics are passed on to offspring in genes, and antibiotic resistance in bacteria, which shows natural selection happening in a short time. This is why the theory is now widely accepted.
How are fossils formed?
Fossils form in three ways: from parts of organisms that have not decayed because one or more of the conditions needed for decay are absent, from parts that are replaced by minerals as they decay, or as preserved traces such as footprints, burrows and rootlet traces. Fossils are found in rocks and show how organisms have changed.
How does antibiotic resistance develop in bacteria?
Antibiotic resistance develops by natural selection. A mutation produces a strain of bacteria that is resistant to antibiotics. When antibiotics are used, non-resistant bacteria are killed but the resistant bacteria survive and reproduce, so the resistant population rises. Because bacteria reproduce at a fast rate, resistant strains such as MRSA can spread quickly, with no effective treatment.
All 4 questions on The development of understanding of genetics and evolution
