16.1 Developing a Theory I. Evolution A. The process by which species change over time B. Theory 1. a broad explanation that has been scientifically tested and supported C. Evolutionary theory keeps developing and expanding 1. many scientists have tested and continue to add ideas

II. Charles Darwin A. English Naturalist, spent 5 years traveling the world on the HMS Beagle

B. Visited the Galapagos Islands off coast of Ecuador (South America) 1. Collected several different species of birds called finches

2. Each are very similar, but differences 2. Each are very similar, but differences can be seen in their bills (or beaks) a. Each bill seems suited to each diet 3. Noticed many of the islands’ plants & animals were similar to mainland a. Darwin believed that island organisms descended from mainland organisms b. Descent With Modification 1. animals modified over time by eating different types of food

C. Breeding & Selection 1. Artificial selection a. the human practice of breeding animals or plants that have certain desired traits 1. ex- dog breeding or horse breeding III. Darwin’s Ideas from Others A. Jean Baptiste Lamarck 1. French scientist that proposed idea of use and disuse. a. if you don’t use your muscles they decrease in size and you pass this on to your offspring b. this idea was eventually disproved

B. Thomas Malthus 1. English economist 2. stated populations increase faster than food supply causing competition C. Charles Lyell 1. Geologist 2. Thought that earth’s processes were gradual and constantly changing 3. Fossils found in layers of Earth show gradual change of species over time