Darwin and the Theory of Evolution (2016)

Review – What does the Theory of Evolution state? Biological evolution is the genetic change in a population of an organism over time. So how and why did Darwin come to develop his ground-breaking Theory of Evolution?

Darwin’s Society In Darwin’s lifetime the Christian biblical idea that about 6,000 years ago god created all the species exactly as we see them, was the accepted belief.

Darwin’s Travels When he was only 22, Darwin was the naturalist on the HMS Beagle. He voyaged around the world with numerous long stops to collect organisms and observe. These observations lead him to conclude that Biblical stories could not be the literal truth.

Darwin’s Observations (p 329) He made many observations and some he later used to support the Theory of Evolution included: Rodents in South America looked like each other and were very different from European rodents. The fossilized glyptodont looked like a modern armadillo.

Darwin’s Observations (p 329) 3. The tortoises, finches and plants on the Galapagos looked like the nearest mainland organisms. 4. Each Galapagos finch specialized in a different food and had a different beak size and shape. 5. Traits are passed from parents to offspring and there was a lot of genetic variation in the offspring. Pacas and capybaras –S. American rodents

Darwin’s Famous Galapagos Finches What are some differences?

Darwin’s Scientific Influences Many scientists in Darwin’s time knew that simple organisms developed gradually and changed to more complex organisms, but they did not know how or why these changes occurred. They were also arguing about the age of the Earth, but they knew it was much more than 6,000 years old.

Darwin’s Scientific Influences The key idea for Darwin was in Thomas Malthus’s proposal that populations produced far more offspring than the environmental resources could support. There was competition for food, water and space that lead to weakness, starvation or death by disease.

Darwin’s Big Idea – Natural Selection Darwin used the term natural selection to describe the process that only the offspring fittest for the environment would survive. We now define natural selection as the different levels of survival and reproduction of individuals due to differences in phenotype.

The Theory of Evolution In Darwin’s famous book, On the Origin of Species, he described how populations underwent descent with modification due to natural selection. Darwin did not use the word evolve because he thought it indicated progress or improvement of a species towards a goal.

Darwin’s Conclusions For evolution to occur Darwin concluded: Organisms must produce more offspring than can survive, because there is competition for resources. There is a lot of genetic variation in a population, and that variation can be inherited. Individuals that are better suited to a location are more likely to survive and reproduce. Evolutionary change is a slow, gradual process.

So What is a Scientific Theory? A scientific theory is based on observations, evidence and facts. A scientific theory is an explanation of a large concept that pulls together many related observations. For example, the Theory of Evolution uses large amounts of evidence from fossils, geology, DNA, and studies of existing plants and animals to account for the origin of life on Earth and its diversity.

Evolution - a Gary Larsen point of view

PBS – Isn’t evolution just a theory. https://www. youtube. com/watch PBS – Isn’t evolution just a theory? https://www.youtube.com/watch?v=85diEXbJBIk&list=PLvFQyVl48bpzzmyVQLpDsWydyBqi_Zc-J PBS – Who was Charles Darwin? https://www.youtube.com/watch?v=zn2bsJYFu_A