In science, theories are statements or models that have been tested and confirmed many times.
Theories have some important properties:
In science, the term "Theory" does not express doubt.
In science, the term theory is used to represent ideas and explanations that have been confirmed through tests and observations
The theory of evolution remains one of the most useful theories in biology because it explains many questions and observations.
Some questions that can be answered by evolution.
Lamarke's Theory of Acquired Characteristics
Some thought that you would gain or lose features if you overused or didn't use them, and you could pass these new traits onto your offspring.
This was known as the Inheritance of Acquired Characteristics
Lamarke's Theory was eventually discarded - PROVEN TO BE WRONG!
Why? Logically it doesn't work. Imagine if you were in a car accident and had a leg amputed. This does not mean that your children will only have one leg. Features gained during life are not passed on to children.
Darwin's Theory of Evolution by Natural Selection
Darwin was a naturalist who observed many species. He is famous for his trips to the Galapagos Islands, his observations of the finches (and other animals) and the book he wrote: "The Origin of Species:
1. Variation exists among individuals
in a species.
2. Individuals of species will compete for resources (food and space)
3. Some competition would lead to the death of some individuals while others would survive
4. Individuals that had advantageous variations are more likely to survive and reproduce.
This process he describes came
to be known as Natural Selection
The favorable variations are called Adaptations
Darwin noted that all the finches on the galapagos island looked about the same except for the shape of their beak. His observations lead to the conclusion that all the finches were descendents of the same original population. The shape of the beaks were adaptations for eating a particular type of food (Ex. long beaks were used for eating insects, short for seeds)
1. Fossil Evidence
2. Evidence from Living Organisms
1. industrial melanism (Kettlewell's moths)
2. dog breeds
3. viruses & vaccines
4. bacteria & antibiotics
5. elepant tusks