(a) The Cenozoic Era began

1. some 65 million years ago once mamals killed off the dinosaurs.

2. 3 to 4 million years ago when pre-human mamals began to walk on two legs.

3. 40,000 to 50,000 years ago when the last ice age ended and modern humans evolved in Africa.

4. 64.5 million years ago when a large meteor wiped out the dinosaurs, opening an ecological niche for mammals.

5. 64.5 million years ago in Africa when early human like mammals first evolved from the apes.

(b) By the end of the Late Paleolithic period of the Stone age,

1. humans had experienced a great leap forward because of the development of fundamentally new energy sources.

2. humans had experienced a great leap forward as shown by the more advance tools and artifacts, but their fundamental energy use was still probably around 5, 000 kilocalories per person per day.

3. humans had experienced only gradual changes to their hunting and gathering lifestyle, and were still using primitive stone and wood tools.

4. human population had expanded throughout Africa, Asia, and Europe with an expanding population of over 10 million.

5. humans had learned how to use fire to refine metals such as copper and iron and make metal tools.

(c) One fundamentally new form of energy that humans first began to widely use in the period of the early civilizations was

1. coal for smelting iron.

2. exercise bikes.

3. charcoal for baking and cooking.

4. wind for sailing vessels.

5. harnessing horses to plow farm fields.

(d) The Industrial Revolution

1. began in France with the development of the steam engine and then spread to the UK and the United States.

2. began in 1550 when the English learned how to use coal to replace wood as a heat source and spread to France and eventually the United States once those areas began to experience wood shortages.

3. ended the use of slaves because the steam engine was much more powerful and easier to control and operate.

4. began in England in the 1780's and spread to France and the United States.

5. transformed society by allowing women to work in factories while men provided food through farming and hunting.

(e) Of the total incoming power to earth of 173,035.3 billion kilowatts,

1. 40,000 billion kilowatts is absorbed by plants.

2. 32.3 billion kilowatts originates from the interior of the earth.

3. 3.0 billion kilowatts originates from radioactivity in nuclear reactors.

4. 370 billion kilowatts is directly reflected into space from clouds.

5. 121,035 billion kilowatts is used to warm the earth and power the weather and climate.