AP BIOLOGY

Detailed explanation-1: -The Ice Ages began 2.4 million years ago and lasted until 11, 500 years ago. During this time, the earth’s climate repeatedly changed between very cold periods, during which glaciers covered large parts of the world (see map below), and very warm periods during which many of the glaciers melted.

Detailed explanation-2: -The fossil record shows that the average size of black bears was large during cold glacial periods and got smaller during warmer time periods.

Detailed explanation-3: -At the height of the recent glaciation, the ice grew to more than 12, 000 feet thick as sheets spread across Canada, Scandinavia, Russia and South America.

Detailed explanation-4: -Over thousands of years, the amount of sunshine reaching Earth changes by quite a lot, particularly in the northern latitudes, the area near and around the North Pole. When less sunlight reaches the northern latitudes, temperatures drop and more water freezes into ice, starting an ice age.