 Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors.  He sailed on HMS Beagle around the globe collecting plant and animal specimens.  Darwin noted that 1) species vary globally 2)species vary locally and 3) species very over time

 Darwin noticed that different, yet ecologically similar, animal species inhabited separated, but ecologically similar, habitats around the globe.  (Rheas, large flightless birds, live in the grasslands of South America look like ostriches, yet ostriches live only in Africa)  Why are there no kangaroos anywhere except in Australia?

 Darwin noticed that different, yet related, animal species often occupied different habitats within a local area.

 In addition Darwin collected fossils. Some looked similar to living species while others did not.  Darwin noticed that some fossils of extinct animals were similar to those alive today. Why did they disappear?

 Hutton – geologist. In 1785 he hypothesized that slow acting geological forces shaped the planet. He estimates Earth to be millions, not thousands of years old.  Lyell published “Principles of Geology” in the same processes affecting Earth today have shaped Earth’s ancient geological features.

 Lamarck – suggested that organisms could change during their lifetime by selectively using or not using various parts of their bodies. He also suggested that individuals could pass these traits on to their offspring, enabling species to change over time.

 In 1798 Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

 When Darwin returned home he studied and read other people’s materials about geological changes.  He also studied the selective breeding of domestic animals and crops.  He found that any domesticated plant or animal bred to accentuate desirable characteristics is the result of artificial selection. (Nature provides variation and humans select the variations that they find useful)  Many vegetables that we eat today came from the wild mustard plant through artificial selection.

 Darwin’s book, published in 1859, was a quick success. It came from the clear and understandable argument that natural selection and selective breeding of animals was in wide use at the time. There was a massive array of biological and fossil evidence to support the argument.  Selective breeding: breeding of organisms to produce certain desired traits in their offspring. It came from the argument that natural selection and selective breeding of animals was in wide use at the time. There was a massive array of biological and fossil evidence to support the argument.

 Individuals that are best suited to an environment (adaptations that enable fitness) survive and reproduce most successfully.  Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species fitness in its environment.

4 Main Points. 1. There is variation with a population. 2. Some variations are favorable. 3. Not all young produced in each generation survive. 4. Individuals that survive and reproduce are those with favorable variations. 5. Descent with Modification Ostriches are the fastest birds on land due to favorable traits such as long, powerful legs.

 Natural Selection leads to organisms that are well suited in particular environments.  It provides a scientific explanation for the history of life on Earth as depicted in the fossil record and similarities evident within the diversity of existing organisms.