Darwinian Evolution Theory

1) There were three themes that set the stage for Darwinian evolution theory. They were the study of fossils, gradualism, and Larmarck's theory of evolution.

2) One point was that many species of organisms presently inhabiting Earth are descendents of ancestral species that were different from modern species. Another point was natural selection, which is the idea that a population can change over generations if the individuals that possess certain heritable traits leave more offspring than other individuals.

3) Larmarck's theory of evolution and Lyell's idea of uniformitarianism.

4) Linnaeus contributed taxonomy. Taxonomy, which categorized life on morphological similarities. These were usually evolutionarily related, so a system was already in place by the time evolution was accepted.

5) The fossil record shows a progression of life forms from simpler ones in the older rocks, to more complex ones in the younger rocks. Since Hutton and Lyell, the geologists, had shown the great age of the earth, the progression of life complexity shown in the fossil record enabled Darwin to reason that the fossil record was evidence that species had evolved over time.

6) Hutton's and Lyell's ideas exerted a strong influence on Darwin. Darwin agreed that if geology change results from slow, continuous actions rather than the sudden events, then Earth must be much older than the 6.000 years that theologians estimated. He then reasoned that maybe the same slow and subtle processes could also act on living organisms.

7) One point was that the parts of the body that are used extensively become larger and stronger while the parts that are not used much deteriorate. Another point was that an organism could pass these modifications to its offspring.

8) Darwin noticed that the plants and animals in temperate regions of South American closely resembled the species living in the South American tropics than the species in Europe. He also compared the fossils to the living species and experienced an earthquake in Chile. That earthquake him realize that natural forces and changes in the environment really affect life. He realized from his experiences on the ship that Earth was very old and was constantly changing.

9) During Darwins visit to the Galapagos Island he observed that these islands had many unique organisms, most of which were similar to but different from the plants and animals from the nearest mainland Ergo, this indicated how population evolved. Darwin called this "descent with modification" meaning an ancestral species could diversify into many descendant species by the accumulation of adaptation to various environments.

10) Isolation and natural selection are some of the elements for the formation of new species.

11) The types of food the finches eat, such as insects/flowers/seeds, were a driving force behind the evolution of the 14 species of finches.

12) Darwin planned to publish his theory after his death but Lyell urged him to publish it before someone