The Quaternary Period includes the most recent 2.6 million years of the geologic time scale and is the time period in which humans first appeared. During the Quaternary Period, 30 percent of Earth's surface was covered by glaciers.
The Quaternary Period is divided into the Pleistocene epoch and the Holocene epoch. The Pleistocene epoch was an ice age, and animals during this period, such as the mastodon, the woolly mammoth and the giant bison, were well-adapted to the cold. Sharks and whales were at the top of the marine food chain, and prey animals included otters, urchins, seals, squid and crustaceans.
The Holocene epoch brought temperature increases that ended the Pleistocene ice age about 10,000 years ago. Holocene climate changes caused the extinction of Pleistocene megafauna, such as sloths and mammoths, and contributed to geographic changes that led to the creation of the Great Lakes. Only a few larger animals survived the changes, including Africa's elephants, rhinoceroses and hippopotamuses.
The first hominid species, Homo erectus, learned to use fire to survive the harsh weather of the Quaternary Period. They developed bigger brains that enabled them to create tools and weapons to outsmart larger predators. The bow and arrow and the spear were Quaternary inventions. Early hominids also began hunting in groups for increased protection and efficiency.