The Theory of Evolution (See Chapter 16 in your text) Evolution Theory Common English Science language A theory is... A theory is... A best guess The result of many A hypothesis experiments that all show the same thing NOT a guess No evidence has been found against it Something you aren’t sure about The processes that have transformed life on earth from it’s earliest forms to the vast diversity seen today. A change in the genes! MANY experiments and observations show the same conclusion What happened in our experiment? Before the industrial revolution After the industrial revolution Which moths were the most common after the trees changed? Why did the population change? Could individual moths change color? How would you observe this in the local environment? Did a new species form? 1. Inherited Variation 1. Inherited Variation 2. Overproduction 1. Inherited Variation 2. Overproduction 3. Struggle to Survive 1. Inherited Variation 2. Overproduction 3. Struggle to Survive 4. Successful Reproduction Thomas Malthus (late 1700s) Units of Food Population Size Malthus said: At some point, we will run out of food! Years Charles Lyell – Principles of Geology The earth is very old Many small changes over a long time can produce big differences How did the giraffe get its long neck? (Early ideas about natural selection) Jean-Baptiste de Lamarck (1809) If an organism uses a body part it will get stronger Then it can pass on that trait to its offspring Acquired characteristics CAN’T be passed on You can only pass on what is in your DNA (which doesn’t change) Voyage of the Beagle (1831 – 1836) Looked at specimens from all over the world Saw similarities and differences and tried to explain them Famous example of finches in the Galapagos Islands Each slightly different with different food sources Ancestor finch arrives on an island Finches spread to different islands, each with a different type of food Birds with beaks that eat the food best survive better and reproduce more There are more birds with the right kind of beak on that island Continues for many years... Another (younger) scientist was studying the same thing Alfred Russel Wallace came up with the theory of Natural Selection too Sent a letter to Darwin asking advice They published the idea together... http://www.pbs.org/wgbh/nova/darwin/program-q-300.html Darwin started thinking about Natural Selection in 1836 He published The Origin of Species in 1859 Why did he wait so long? What do you think?