Objectives: Kids will learn who Darwin was and how he came up with the theory of evolution. They will simulate Darwin’s studies on the Galapagos Islands by pretending to be birds, using tongs as beaks and attempting to eat different size seeds on different “islands.” This exercise will show how adaptation works – that birds with the right size beak for the food on their island will survive and over time the bird population will adapt.
Materials: large tongs, small tongs or clips, Tupperware containers, plastic cups, sunflower seeds (or other small seeds), whole walnuts (or other large seeds/nuts), and photos of Darwin, the Galapagos, and birds with different beaks (optional)
[Hold up a picture of Charles Darwin and ask if they know who he is. Tell them a bit about Darwin.]
Charles Darwin was an English naturalist. Do you know what a naturalist is? It is someone whose job is to observe nature, ask questions and try to understand everything in the world around us – plants, animals, everything – and how they interact.
Darwin lived a long time ago. Does anyone know what he is most famous for? [Pause to see if anyone says “the theory of evolution”.]
Darwin is famous for something called the theory of evolution. This theory explains how animals, plants, even bacteria change over time to fit in better (and survive better) in their environment.
Darwin came up with this theory when he was traveling around these islands. [Hold up picture of Galapagos Islands]
Does anyone know what these islands are called? [Wait for responses.]
They are called the Galapagos Islands, and they are here, in the Pacific Ocean, off the coast of Ecuador in South America. [Hold up larger map and point out the Galapagos.]
Darwin noticed that there were lots of birds on the islands, and that they all looked slightly different depending on what island they were on. [Hold up picture of finches and point out differences in beaks.]
At first, he figured they were all different kinds of birds because their beaks looked so different. But, being a good naturalist, he realized that they were, in fact, all the same kind of bird – a kind of bird called a finch.
He was really curious why the finches on each island had such different beaks if they were all finches. He thought that maybe something might have forced the finches to change their beaks, but he realized you can’t make something change the way it looks. You can’t force a polar bear to be purple instead of white. You can’t force a giraffe to have a short neck. I can’t force you to have different color hair. Animals look the way they look because their DNA makes them look that way.
So, to figure out why the beaks all looked different from island to island, he thought about what the beaks do. What is the job of a beak?
[Wait for response…it should be something about eating or collecting food.]
Since the beak has to do with collecting food and eating, he thought about the types of food that could be found on the different islands, and that seemed to be the answer.
To figure it out, we need to do a little experiment. Who wants to help?
- Give each person two “finches” (large tongs and small clips). Show them how these represent large and small beaks on two different types of finches.
- Present each person with two containers. Explain that each of the two containers represents an island and each island has different types of food. On one island the food (nuts, seeds, whatever) are small, on one they are large.
- Have each person make their birds eat (pick up the seeds with each of their clips or tongs) on each island.
- They should see that the small clips pick up the small seeds, but be unable to pick up large food. The large tongs should be able to pick up large food, but not be very efficient at picking up small seeds.
- Ask them to talk about what they would expect to see over time. If a bird can’t eat, have them set the tongs down and not use them anymore (it can’t eat on that island so it starves and dies off, and can’t be found on the island anymore). The small beaks can’t eat large food so they die off on that island. The large beaked birds probably won’t survive on the small-food island because they can only get little bits of food at a time and need large amounts to survive.
- Eventually, you should see all small-beaked birds on the small food island, and large-beaked birds on the large island.
- Now, show them the picture of Darwin’s finches again and ask them to explain why they might see such differently shaped beaks on the different islands of the Galapagos.
- If you want to extend it a bit, tell them that we made this a really simple example (all small food on one island…all big food on the other island), but ask what they’d expect if an island had both kinds of food.
So, by noticing that finches on the different islands had beaks that were adapted to their environment, and realizing that finches whose beaks weren’t adapted wouldn’t survive, Darwin was able to start working out his theory of evolution.
Over time he realized that this theory seemed to explain why all animals and plants look or act the way they do, and 150 years later the theory of evolution is considered to be one of the most important ideas in all of science.
Post-activity discussion questions:
- What do you think would happen if you went to the Galapagos, noticed many birds with both small and large beaks on an island with only large seeds, and then came back in a hundred years? What would you see the second time?
- Why does adaptation of a population take so long? Why do you think it can’t happen within one bird’s lifetime?
- How do you think Darwin figured out his theory of evolution (remember – this theory explains how animals, plants, and bacteria change over time to fit in better (and survive better) in their environment) based on what he saw in the Galapagos?
- (if they have done Module 1 on genetics and inheritance) Do you remember genes and inheritance from last time? Why do you think it is important for genes to be inherited in this example?