Basic theory of evolution - all species have evolved from simple life forms. The simple life forms first developed more than 3 billion years ago.
Evolution has taken place over millions of years. Charles Darwin wrote one of the first major scientific books on this subject.
Darwin's ideas caused a lot of controversy, as they conflict with religious views about the creation of the world and the creatures living in it.
- English naturalist - studied variation in animals and plants.
- Explained his ideas on evolution in a book called 'On the Origin of Species'.
The species adapt and change by:
- Variation - in any population of organisms there will be some difference.
- Overproduction - many organisms produce more offspring than necessary.
- Struggle for existence - there is competition for survival and resources between the organisms.
- Survival - those with helpful characteristics are more likely to survive and breed.
- Useful characteristics are inherited by offspring.
- Gradual change of the species over a period of time as useful characteristics are passed to offspring.
Support for Darwin's Theory
Support for Darwin's theory:
- Antibiotic-resistant bacteria - microorganisms such as bacteria and viruses reproduce rapidly and can evolve in a short period of time. Its DNA can be damaged or changed during replication. Occasionally the mutation is beneficial to the bacteria. For example, it may allow resistance to certain antibiotics.
- DNA - scientists examine the DNA from different species and use the data to see how closely related the two species are. By doing so, scientists can compare results with ideas about how organisms have evolved. They found that DNA data supported the theory of evolution
All new scientific evidence is assessed by the scientific community to validate the theory. This is done through: scientific journals, the peer review process, and scientific conferences.