Section: Science

12)

The polar bear's dense fur and an exceptionally thick layer of fat under its skin protect it against the freezing temperatures of the habitat.

How is natural selection in the evolution of a thick coat of fur in polar bears best explained?

1. Polar bears with thicker fur only mated with other polar bears with thick fur.
2. Polar bears with thinner coats of fur were killed off by polar bears with thick coats of fur.
3. Polar bears with thinner fur head south for the winter
4. Polar bears with thinner fur did not survive because they were not well suited to the environment.
5. Polar bears fur grew thicker because of genetic mutations of the animals.

Natural Selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution. In this case, polar bears with thicker fur were able to better survive in their environment while thinner furred polar bears died off over time.