In Sapiens A Brief History of Humankind, Yuval Noah Harari explores the development of humankind.
Harari starts by outlining that humans first evolved in Africa about 2.5 million years ago and we were completely unremarkable until around 70,000 years ago, when human culture began to form.
Most people are aware than Neanderthals co-existed with humans for a time, but Homo Sapiens (meaning “wise man”) and Homo Neadnerthalensis were just two of multiple human species that roamed the earth at the same time. The book explores two opposing theories of Interbreeding and Replacement which outline how homo sapiens evolved and the other human species died out. The reality is likely to be a combination of “ethnic cleansing” and interbreeding. It’s important to note that the average European shares 1-4% of their DNA with Neanderthals, adding further evidence to the theory of interbreeding.
So why did Homo Sapiens survive and prosper, while the other human species died out? Harari explains that human history has gone through 3 large revolutions that other species didn’t:
- The Cognitive Revolution
- The Agricultural Revolution
- The Scientific Revolution
The Cognitive Revolution occurred 70,000 – 30,000 years ago and was prompted by the discovery of fire.
Fire enabled us to cook food, which reduced the amount of energy our bodies needed to use to digest food. This paved the way for a smaller intestinal tract and the development of a larger brain, which used 25% of the body’s energy.
The growing intelligence of our species led to improved communication, which allowed us to organise, collaborate and form relationships that even the other human species at the time couldn’t match. We were able to hunt more effectively, quickly (in evolutionary terms) taking us from the middle of the food chain (400,00 years ago) right to the top.
We were suddenly able to tell stories and share ideas and myths. As far as we understand, we are the only species that can comprehend things that we’ve never personally experienced. These stories and myths (religions, ideologies) facilitated cooperation and led to the creation of ideas such as fairness and justice, which were essential for cooperation between larger groups.
Thanks to our new abilities, we didn’t have to didn’t have to wait for another few million years of evolution to take place for our behaviour to change. The way we behaved and cooperated could be changed by adapting the stories and ideas that we shared. Our brains and bodies have remained unchanged since we passed through the cognitive revolution.
While, we like to think that we are smarted than our ancestors, but there is no evidence that we’re more intelligent than humans 30,000 years ago. As a collective, we possess more knowledge and understanding of the world, but at the individual level, ancient hunters and foragers were for more skillful and varied in their knowledge of the world than modern humans. In fact, we are more likely to pass on undesirable or unremarkable genes nowadays. Undesirable traits have a negative impact on a person’s ability to survive. 30,000 years ago, people possessing these disadvantageous traits often wouldn’t survive long enough to pass them on. Nowadays however, finding food is as easy as walking into a supermarket and modern cities put a huge buffer between us and wild animals.
Once we passed the cognitive revolution, homo sapiens quickly spread throughout the world, travelling across the sea to Australia. 16,000 years ago, humans first made their way across the Siberian peninsular to America and right down to the South America – to our knowledge, the quickest expansion of a species to ever occur.
Even given these remarkable achievements, physically and mentally, we are essentially the same animals that we were 30,0000 years ago. This lack of biological change is partially to blame for many of the stresses we feel in our modern lives. Many of our daily habits and experiences are unnatural to us:
- Gorging on high calorie foods makes sense in the wild, but not when there is an abundance of food.
- Humans naturally fall into a bi-phasic sleep cycle where our sleep is broken into 3 parts (2 cycles at night and 1 in the afternoon) not a single 7-8 hour block.
- A single city contains more people than the average human might meet in 100 lifetimes.
- The concept of privacy is very new, but so is loneliness; we were always surrounded by a group of trusted friends and family.
The cognitive revolution ended around 10,000 years ago as humans began to built permanent settlements and so began the agricultural revolution. Impressively, this revolution happened independently in many areas of the world. The Agricultural Revolution is responsible for the huge growth of the human population and the creation of towns and cities. I’ll explore the Agricultural Revolution in another post.
If you’re interested in learning more, I’d implore you to pick up Harari’s book Sapiens A Brief History of Humankind – it’s a great read and incredibly informative.