Evolution in general is a long-discussed topic, where opinions vary greatly. Although there are many different opinions and statements, there are facts that prove that animal evolution is indeed true. Evolution is “change in a dignified line” (Starr, Evers, Starr, p.192). There are many forms of evolution, but I focus on the evolution of many different animals, from animals adapting to their environment/climate to different theories of their evolution.Charles DarwinCharles Darwin was a naturalist and geologist, he is widely known for his evolutionary theories theory. “Darwin's general theory presupposes the development of life from non-life and emphasizes a purely naturalistic (undirected) "descent with modifications". That is, complex creatures naturally evolve from more simplistic ancestors over time. Simply put, when random genetic mutations occur within an organism's genetic code, beneficial mutations are preserved because they aid survival – a process known as “natural selection.” These beneficial mutations are passed on to the next generation. Over time, beneficial mutations accumulate and the result is a completely different organism (not just a variation of the original, but a completely different creature)” (Darwin's Theory of Evolution). The term Darwinism is “based on Darwin's six key observations and the inferences he drew from them.1. That species has great fertility and produces more offspring than can grow to adulthood in a given environment.2. That after an initial increase, species populations remain about the same size with only modest fluctuations in numbers.3. That food sources have defined limits but are mostly constant.4. This, because of the three observations… middle of paper… seal pups are thinner and thinner because their prey is migrating to colder waters. Furthermore, due to global warming and the high level of carbon dioxide in the air, plants absorb the toxin and use it as a defense against herbivores. There are caterpillars that transform into moths that eat plants as a food source, in turn "a University of Rhode Island student found evidence suggesting that some songbirds may avoid eating insects that consume leaves exposed to high levels of carbon dioxide" (climateark.org ). In terms of reproduction it is documented that Canadian red squirrels reproduce 18 days earlier, swallows lay their eggs 9 days earlier, some American flowers bloom earlier and also due to the rise in temperature it has been documented that this influences the sex of Nellas hawksbill turtle, the hatchlings were with the majority of females and males.