Evolution

In chapter 22 “descent with modification view of life”, the author explained how Darwin first found his theory of Evolution and developed his idea lately and also mentioned the main points of Darwin’s theory.
From the article we know that Darwin was a naturalist between 1809-1882 and he started a five years trip to travel around the world when he was 22 years old .During his trip he have collected may flora and fauna and his most famous theory of Evolution was first founded in Galapagos, an archipelago of volcanic islands off the coast of South America. He discovered that a group of bird called finches which lived in different islands in Galapagos, although they are belong to one species each of them have unique feature to suit their different living condition. Furthermore according to the fossil he founded he began to doubt that the year of earth is much longer than what people thought at that time. Is it possible that the new species is created from the ancestor through the progress of a slowly accumulation of adaptations to the environment he asked himslef?
Darwin’s theory include two main ideas, one is that the different between species can be explained by Evolution and another is the adaptive evolution is because of natural selection.
First of all, all life related to previous form. According to Darwin, life form is like the form of a tree, the branching represents the present organisms and the trunk represents the ancestors, all the branching are from the trunk. For example the Asian elephant and African elephant, although they live in different area but obviously they are all from one same ancestor.
Secondly, natural selection may create new species. Evolutionary biologist Ernst Mary thought that Darwin’s Natural Selection is more about struggle for existence. Because of the pressure to survive many organisms will over reproduce and the one who fit the environment best will pass their traits to the next generation so the next generation will have a better chance to survive . Time after time a new species may be created by natural selection. The whole working progress is just like the artificial selection, for example farmer always choose the cow produce most of the milk to get pregnant so the baby will also be to produce as much milk as her mother dose and maybe more. As a result the baby cow will be chose to get pregnant in the future.
For summary the authors mentioned three points that people always confused about them. First, the smallest unit can evolve in natural selection is a population, the individuals don’t evolved .Second, organisms can only pass DNA to next generation but not their knowledge, there is a different between the adaptation organisms acquires during their life time and inherited adaptations which happen in a long period of time .Third, a trait suit in one environment means nothing in another environment cause the environment changes all the time and so does the natural selection.