Lesson 4

Why do piloses have skinnier noses nowadays?

Big Idea: A trait variant can be beneficial to an individual, harmful or neither, depending on environmental conditions. A beneficial trait variant makes it more likely an individual will be healthy, survive, and have many offspring. That trait variant will become more common in the population over time. This is the process of natural selection.

Activity: A storybook about animals called piloses provides evidence that the proportion of individuals in a population with a particular trait variant might change when the environment changes. Students participate in a simulation, where they model the process of natural selection.

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