What does it mean to be human? In his book that spans two and a half million years, Israeli historian Yuval Noah Harari seeks to find out. He does into detail about the changes that made Homo (‘man’) into Homosapiens (‘wise man’). Harari delves into the subjects of a large brain, tool use, complex social structures and more. In the beginning of human existence, there were several different human species on the planet and we putzed around pretty unremarkably. Then something happens and Harari doesn’t even have a clue what happened. He points out that it’s not entirely obvious what first spurred the development of the human species’s extraordinary intelligence. Today, of course, there is just one human species alive. How did we, the Homo sapiens become so successful and others did not? Harari believes it was our unique cognitive abilities that made the difference.
400,000 years ago Homo sapiens were just one of many different human species, all competing for supremacy. Today we see different species of dogs or cats, there were different species of humans. We can't think of human evolution in terms of ape-like ancestors gradually evolving more modern features in a linear fashion. Instead, multiple human species evolved in parallel and coexisted, sometimes side-by-side. Here are some, just to name a few.
1.9 million - 143,000 years ago - Homo erectus lived from about 1.9 million years to most recently 143,000 years ago. Homo erectus originated in Africa and spread through India, China, Georgia, and Java. Homo erectus were generally in the range of 4 feet 9 inches to 6 feet 1 inch with a weight of around 88 to 150lbs.
600,000 - 30,000 years ago - Homo neanderthalensis have only 0.12 percent of their DNA that is different to modern humans. The Neanderthal was believed to have existed from about 600,000 to 30,000 years ago, and lived throughout Europe and southwest to central Asia. The Neanderthal and the modern human brain were similar at birth. However, in adulthood, their brains became larger. They were stronger than modern humans with a height around 5 ft 5 inches.
335,000 - 226,000 years ago Homo naledi originated in South Africa and were generally in the range of 4 feet 9 inches 88 to 150lbs.
160,000 years ago to present - Homo sapiens, the only humans still in existence, came mainly from East Africa. Homo sapiens lived together, hunted food, and evolved to such an extent that they could cope with the climatic changes that occurred. They are believed to have existed since 160,000 years ago.
95,000 - 17,000 years ago - Homo floresiensis or Hobbits, were believed to have lived from 95,000 to 12,000 years ago in Indonesia. They were quite small in size, around 3.5 feet and weight around 75 pounds, with a tiny brain. There is evidence that Homo floresiensis made stone tools and used to hunt small elephants and large rodents.
Each species adapted to its own environment. Some were big, fearsome hunters, while others were dwarf-like plant gatherers. As different as each species may have been, there is evidence of interbreeding among them. Scientists mapping the Neanderthal genome, for example, discovered that people of European origin today have a small percentage of genes from their Neanderthal ancestors. Humans were in the middle of the food chain during this time. Then , there were three revolutions that changed human history.
1. 70,000 years ago there was a Cognitive Revolution.
During the Cognitive Revolution, humans went to the top of the food chain because of the evolution of the massive human brain. Mammals weighing 130 pounds have an average brain size of 12 cubic inches. The earliest humans, 2.5 million years ago, had brains of about 36 cubic inches. Modern Sapiens have a brain averaging 80 cubic inches. Neanderthal brains were even bigger. In Homo sapiens, the brain accounts for around 2 percent of total body weight, but it consumes 25 per cent of the body’s energy when the body is at rest.
Early humans paid for their large brains in two ways. They spent more time in search of food and their muscles atrophied. However, with the large brain, humans could outsmart prey and capture them, they learned to use fire to cook the meat.
Something else that also changed was the upright gait required narrower hips, constricting the birth canal, and this just when babies’ heads were getting bigger. Death in childbirth became a major hazard for human females. Compared to other animals, humans are born prematurely, when many of their vital systems are still under-developed. A colt can trot shortly after birth; a kitten leaves its mother to forage on its own when it is just a few weeks old. Human babies are helpless, dependent for many years on their elders for sustenance, protection and education.
Animals that are at the top of the food chain acquired the position over millions of years, however Humans took the position very rapidly. Again, no one knows what happened to cause this. The rest of the food chain was not prepared and humans weren’t prepared either. Harari believes this is why modern humans feel anxious and stressed because we are not familiar with being at the top. We are used to waiting to eat from a carcass after the large predators have finished, then the smaller animals would eat. Now, we have weapons to kill prey and predators that would have taken our food.
Language also evolved during the Cognitive Revolution in Homo sapiens as a way to gossip about other human’s reputations to know who one could or could not trust in the group. Language allows people to communicate about abstract concepts that bonds humans together and permits cooperation among much larger populations than other animal tribes can sustain.
Large numbers of humans started to collaborate by sharing common myths and beliefs. An imagined reality is not a lie because the entire group believes it. As far as we know, only humans can talk about things we’ve never seen, touched, smelled, etc. Myths allowed groups larger than 150 to be managed as a whole.
2. 10,000 years ago there was the Agricultural Revolution
Homo sapiens are the only human species left on the plant. There are two theories.
Interbreeding theory where all species became one and the Replacement theory where Homo sapiens killed the other species left. Harari believes that the Neanderthal and Hobbits were too familiar to ignore and too different to tolerate so the Sapiens killed them. This would not be out of the realm of possibility since modern humans still act this way.
Homo sapiens began to spend nearly all their time domesticating a few plant and animal species. Harari believes that plants manipulated people to expanding their habitats and multiplying their genes. The plant species did the same for sapiens.
This monoculture produced unhealthy diets, sedentarism and farm animals spawned infectious disease. Most sapiens had to engage in back-breaking labor. Social hierarchy, inequalities became a sapien invention during this time and the population ballooned.
3. 500 years ago The Scientific Revolution
Humankind begins to admit its ignorance and acquires unprecedented power fueled by imperialism and capitalism. Rather than conquering only neighboring territories as did imperialists in the past, Europeans broke with convention by setting out for distant shores to conquer uncharted land and gain knowledge. They surveyed the natural resources of distant lands, collected information about rare animals and catalogued it. They began to trace their origins and to dig up to explore forgotten ruins.
The military-industrial-scientific complex led to a period of European dominance, followed by the globalization of science and its power. Harari puts into perspective the truly awesome feats that humans have accomplished over the 500 years since the Scientific Revolution, such as discovering microorganisms, splitting the atom and landing on the moon.
Harari ends the book by hypothesising where the homo sapiens species is headed. He considers genetic engineering, artificial intelligence and the possibility that technology may intimately integrate with or overtake us. This clear-sighted section foresees a future that will surely challenge our notion of humanity. We are already beginning to see this take shape.
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