Chapter 11
Evolution
Why are polar bears white instead of brown or black? White
fur helps polar bears blend into the Arctic ice and snow so
they can hunt more successfully. White fur has a survival
advantage for polar bears. As millions of years passed, and
generations upon generations of polar bears survived and
reproduced, natural selection occurred in the bear population
to favor white fur. Evolutionary concepts like adaptation and
natural selection are featured in this chapter.
- What is evolution and how does it work?
- What can fossils tell us about the history of life
on Earth? - What causes animals and plants to become
extinct?