Sapiens: A Brief History of Humankind

by Yuval Noah Harari

The more eastern regions of Asia were populated by Homo erectus, ‘Upright Man’, who survived there for close to 2 million years, making it the most durable human species ever.

The truth is that from about 2 million years ago until around 10,000 years ago, the world was home, at one and the same time, to several human species.

Why are giant brains so rare in the animal kingdom? The fact is that a jumbo brain is a jumbo drain on the body. It’s not easy to carry around, especially when encased inside a massive skull. It’s even harder to fuel. In Homo sapiens, the brain accounts for about 2–3 per cent of total body weight, but it consumes 25 per cent of the body’s energy when the body is at rest.

But the best thing fire did was cook. Foods that humans cannot digest in their natural forms – such as wheat, rice and potatoes – became staples of our diet thanks to cooking.

Since long intestines and large brains are both massive energy consumers, it’s hard to have both. By shortening the intestines and decreasing their energy consumption, cooking inadvertently opened the way to the jumbo brains of Neanderthals and Sapiens.1

Sapiens had already populated East Africa 150,000 years ago, they began to overrun the rest of planet Earth and drive the other human species to extinction only about 70,000 years ago.

The appearance of new ways of thinking and communicating, between 70,000 and 30,000 years ago, constitutes the Cognitive Revolution.