Interest Grabber A Trip Around the World While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises. Section On a sheet of paper, list five animals that you have encountered in the past two days. 2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.) 3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.

* Charles Darwin contributed more to our understanding of evolution then anyone * In 1831, he set sail from England to go around the world * Darwin came up with a revolutionary hypothesis of how the way of life changed over time * His ideas have become the Theory of Evolution

* Darwin was fascinated on how wherever he traveled animals seemed suited for the environment they lived in * He collected fossils and saw how creatures of the past resembled those still living * The Galapagos Islands is where he was most fascinated

Pinta Island Intermediate shell Pinta Isabela Island Dome-shaped shell Hood Island Saddle-backed shell Hood Floreana Santa Fe Santa Cruz James Marchena Fernandina Isabela Tower

* Evolution—change in organisms over time. (Today, defined as a genetic change in a species over time). * The expression “evolutionary theory” refers to two different sets of ideas: 1. The idea that all organisms are descended from a single ancestor (descent with modification). 2. Ideas of how organisms have changed over time. (While scientists still debate #2 there is agreement about #1. Debate about #2 centers around relative contributions of different mechanisms). * Theory—explains current observations. This explanation may serve as a basis for generating new predictions.

* Observations/Predictions: 1. Organisms are organized into groups of similar species that are part of larger groups and so on, with all life sharing one common characteristic (RNA is found in all living things). * Evidence for relationships between different organisms may be morphological, embryonic, physiological, biochemical, etc. 2. The fossil record reveals a general progression from smaller, simpler forms of life through larger, more complex forms over long periods of time. * Evolution (descent with modification) explains these observations and predicts that new organisms/fossils will fit these same patterns.