Theories are produced in 4 steps:
1. A hypothesis is produced from observations
2. The hypothesis is tested by gathering data
3. The data is either proved to support or disprove the hypothesis
4. The hypothesis is then discarded or maintained.
Darwin's theory was that of natural selection - 'survival of the fittest':
All life comes from a common ancestor. Animals mutate to adapt to their environment. This makes them more likely to survive. These mutations are then passed on to their offspring, causing variation in a species. The evidence for this theory is the fossil record.
Lamarck thought that every animal evolved from primitive worms. He also said that the more an organ was used, the bigger it got, and if it was used less, it would grow smaller and eventually disappear. This is caused use and disuse.
Lamarck believed in the passing on of aquired characteristics. For example, if a man developed strong shoulders from swimming, his children would be born with strong shoulders.
There is no evidence for this theory - it is inaccurate.
Doubts in Darwin
Darwin's theory was not believed at the time because:
- It went against the church
- There was insufficient evidence
- No one knew about DNA, genes or inheritance