Summary of Sapiens : A Brief History of Humankind by Yuval Noah Harari Human cultures began to take shape about 70,000 years ago. There have been three major revolutions in human history: the cognitive revolution, the agricultural revolution, and the scientific revolution. Prehistoric humans (2 million years old or so) were no more important and impressive than other mammals. Homo Sapiens means “wise man.” Humans first evolved in Africa about 2.5 million years ago. The author believes it is unlikely Homo sapiens will survive for another 1,000 years. From about 2 million years ago until 10,000 years ago, multiple human species roamed the earth together. The depiction of man evolving from hunched over to upright incorrectly displays human evolution as a linear trajectory. In fact, the species lived simultaneously. Humans have huge brains for their body size. Human brains account for 2-3 percent of body size, but use 25 percent of energy. Human kind was very much in the middle of th...