As in our activity at Common Ground Animal Adventure Camp: Week 1, we ran an activity at the Peabody Museum summer camp that emphasized the fact that animals evolve mouthparts that allow them to eat the food that is available to them in their environment.
We introduced mouthpart evolution by asking the campers to look at pictures of different types of animal skulls. By looking at the different skulls, the campers were able to infer what types of food different animals eat. We then played a game to illustrate how animal mouthparts evolve.
Carrot Island and Bean Island
Campers were randomly assigned to be a bird with a chopstick beak or a bird with a skewer beak. We started the game with three skewer birds and three chopstick birds on “bean island” and three skewer birds and three chopstick birds on “carrot island.” Carrot island had carrots for food and bean island had dried beans for food. We used flour to draw the island perimeters in the grass.
Which type of bird do you think collected the most food on each island?
After each round of the game, the group on each island that collected more food gained a new member to their population. If the skewer birds collected more carrots on carrot island, the skewer bird population grew by gaining a new teammate. In contrast, if the chopstick birds did not collect as many carrots, they lost a member of their population. The same applied to bean island. At the end of the game, we found that the population on carrot island evolved skewer beaks, whereas the population on bean island evolved chopstick beaks.
Not only does this demonstrate how mouthparts evolve to allow animals to successfully take advantage of the food available to them, but it also shows that evolution depends on the environment. In short, there is not one “right” type of mouthpart. Rather, different types of mouthparts are advantageous under different environmental conditions and this leads to the evolution of diverse traits.
We ended the activity by relating the results of the game the famous example of beak evolution in the Galapagos finches (see Animal Adventure Camp: Week1 for a detailed description of Galapagos finch evolution).
We ended the activity by asking the campers to take one last look at their chopsticks or skewers. As it turns out, some of the chopsticks and skewers had a pattern drawn on them and others did not. We asked the campers whether having a pattern on their faux mouthparts influenced how much food they were able to collect. The campers told us that whether there was a pattern or not on their mouthpart did not influence how hard or easy it was to collect food.
We explained to them that just like the pattern on the skewers or chopsticks did not make it harder or easier to collect food, in nature, animals often have traits that are neutral, rather than adaptive. Take for example, eye color in humans. Some people have brown eyes and some people have blue eyes, but people with brown eyes don’t see any better than people with blue eyes. So, in humans, eye color is an evolutionarily neutral trait.