4. Individuals with variations that help them to survive and reproduce tend to live longer and have more offsprings than organisms with less useful features.

5. The offsprings of survivors inherit the useful variations, and the same process happens with every new generation until the variation becomes a common feature.

6. As the environment changes, the organism within the environment adapt and changes to the new living conditions.

7. Over a long period of time, each species of organism can accumulate so many changes that it becomes a new species, similar to but distinctly different from the original species. All species on the earth arise in this way.

8. Evolution is a slow and continuous process. There are some limitations and objections to the Darwin theory. Many new theories like synthetic theory, mutation theory are put forward

We have seen variations in a population of species, where the organism contain the traits that helped to adapt to the environment. These organisms are going to survive more efficiently. But in the same population the organism which contains the non beneficial traits may not be adapted in the environment. They are going to perish or eliminated slowly, like red and blue beetles in a population which we have discussed earlier in this chapter. These small changes within the species for example colour or