Darwin's theory of natural selection
States that all living organisms have evolved fro simple life forms that developed more than 3bn years ago. Relatively rapid evolution can occur if a new form of gene occurs due to mutation and there is a large change in the environment.
- Within species there is genetic variation due to random mutations in individuals
- Individuals with characteristics best suited to the environment are more likely to survive and reproduce successfully
- The genes that have enabled these individuals to survive are then passed on to the offspring and the next generation
- Conflicts with religious beliefs
- Was no evidence at the time as it is a slow process
- Didn't explain how variations within a species occur (was no knowledge of genes & DNA until 50 years later)
Lamarck's theory of evolution
Law of inheritence of acquired characteristic
- Environmental factor (e.g weight training) causes an acquired characteristic (bigger muscles)
- Acquired characteristic inherited by offspring (e.g. children have big muscles)
- Acquired characteristics do not have a genetic basis
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