Why evolution is now accepted
- Today, evolution by natural selection is accepted by nearly all scientists.
- It became accepted once there was enough evidence to support it.
- A key step was realising that inherited features are carried from parents to their offspring by genes, which finally explained how natural selection could work.
- The two main further lines of evidence are the fossil record and antibiotic resistance in bacteria.
Note
Darwin could not explain how characteristics were passed on; the discovery of genes provided the missing mechanism.
Evidence from fossils
Definition
Fossil
The preserved remains or traces of an organism from many thousands or millions of years ago, usually found in rock.
- Fossils are the preserved remains or traces of organisms from millions of years ago, found in rock.
- Arranged by the age of the rock they are found in, fossils show that organisms have gradually changed over time.
- This is strong evidence that today's species evolved from earlier, different ones.
Note
How fossils form, and why the fossil record is incomplete, are covered in the fossils section.
Evidence from resistant bacteria
- Antibiotic-resistant bacteria are living evidence for evolution happening now.
- When antibiotics are used, bacteria with a resistance allele are more likely to survive and reproduce.
- Over a short time the whole population can become resistant, which is natural selection in action.
- Because bacteria reproduce so quickly, this evolution can be observed within a person's lifetime.
Key Idea
Fossils show that species have changed over millions of years, while resistant bacteria show evolution happening within years.
Self review
- Why is the theory of evolution now widely accepted?
- Name the two main lines of evidence for evolution.
- What does the fossil record show about living things?
- How do antibiotic-resistant bacteria provide evidence for evolution?