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 Homo Sapiens (meaning “wise man”) for a time, but Homo Sapiens and Homo Neadnerthalensis were just two of multiple “human” species that roamed the earth at the same time. The book explores two opposing theories; Interbreeding and Replacement (ethnic cleansing) which outline how homo sapiens evolved and the other human species died out. Replacement dictates that over time we out-competed our human cousins for food and regularly killed off many members of these species.
The Interbreeding theory suggests that we interbred with the other human species until only modern homo sapiens were left. 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.
Harari goes on to say that the reality is likely to have come about from a combination of replacement and 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 need to digest it. This paved the way for a smaller intestinal tract and also meant we had more energy to spare, leading the development of a larger brain, which used 25% of the body’s energy.
Larger brains led to increased intelligence, which resulted in improved, more complex communication, allowing us to organise, collaborate and form relationships that 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.
Humans began telling stories and share ideas and myths. As far as we understand, we are the only species that can comprehend ideas and events 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.
Unlike other animals, 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 relatively unchanged since we passed through the cognitive revolution.
So, while we like to think that we are smarter now, than our ancestors, 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. As society has developed, we’ve relied less on survival skills and more on economical skills. Due to this, we are actually 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; most people never come face to face with an apex predator outside of a zoo.
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.