Sapiens

The Evolution of the First Humans

Millions of years ago, humans were just ordinary animals. They lived in the shadows of larger predators, making no more impact on the environment than a jellyfish or a gorilla. They experienced the same emotions we do today, but they were entirely insignificant on a global scale. Nobody, least of all the humans themselves, had any inkling that their descendants would one day walk on the moon or split the atom.

We are used to being the only human species, but for most of our history, we had many siblings. While our ancestors evolved in Africa, other humans settled in Europe and Asia, adapting to their environments in different ways. The Neanderthals became bulky and cold-resistant in the north, while on the island of Flores, humans evolved into a dwarf species to survive on limited resources. For a long time, at least six different species of man walked the earth at once.

All these human species shared a defining trait of an exceptionally large brain. This was a risky evolutionary bet because a big brain is a massive drain on energy. To fuel our neurons, humans had to spend more time foraging and sacrifice physical strength. We diverted energy from biceps to neurons, meaning a chimpanzee could easily rip a person apart but could never win an argument with a human.

Standing upright also changed our destiny by freeing our hands to use tools. However, this narrowed the birth canal, meaning human babies had to be born prematurely compared to other mammals. A colt can trot shortly after birth, but a human infant is helpless for years. This dependency forced our ancestors to develop deep social ties and cooperate within a tribe, making us uniquely flexible and teachable.

Fire was the tool that finally broke the limits of our biology. It gave us a weapon against predators, a way to transform our environment, and the ability to cook. By pre-digesting food with fire, we could eat more calories with less effort. This allowed our intestines to shrink and our brains to grow even larger, as the body no longer needed to waste energy on long digestive tracts.

About 70,000 years ago, our species, Homo sapiens, left Africa and encountered these other human groups. Within a relatively short time, all our siblings vanished, whether we interbred with them or simply out-competed and slaughtered them. We became the sole survivors of the human family, though small traces of Neanderthal and Denisovan DNA still live on in some of us. Today, our dominance is a very recent development driven by a new way of thinking and communicating.