Seven million years ago, there were no humans on Earth. Today, there are eight billion of us. So, how did a group of African apes become the people who built cities, wrote books, and walked on the moon? This is the story of how humans evolved and how our earliest ancestors really lived.
First, a common myth: humans did not evolve from chimpanzees. Instead, we share a common ancestor with them that lived around seven million years ago in Africa. One of the oldest fossils on our side of the family, Sahelanthropus, was found in Chad.
By about three point two million years ago, our relatives were walking on two legs. The most famous of them is Lucy, an Australopithecus found in Ethiopia. She stood barely a meter tall, and her brain was no bigger than a chimp's. But footprints preserved in volcanic ash at Laetoli prove her kind walked upright, just like us.
Then came tools. The oldest known stone tools from Lomequeui in Kenya are about three point three million years old. Later, around two point four million years ago, a species called Homo habilis made simple stone choppers at places like Olduvai Gorge. With sharp stones, our ancestors could cut meat and crack bones for marrow.
And something remarkable began to happen: brains grew. A chimpanzee's brain is about four hundred cubic centimeters. Homo habilis reached around six hundred, Homo erectus about nine hundred. Today, our brains average around thirteen hundred and fifty, more than three times the size of a chimp's.
Around one point nine million years ago, Homo erectus appeared tall with long legs. It was built for walking and running great distances. Erectus became the first human to leave Africa, reaching Georgia, India, China, and the islands of Indonesia.
Erectus and its descendants also mastered fire. Burnt bones at Wonderwerk Cave in South Africa may be a million years old, and by about four hundred thousand years ago, fire was used regularly. Cooking made food easier to digest, giving more energy to growing brains, and around the fire, people gathered, shared, and talked.
In Europe and Western Asia, a cousin species evolved, the Neanderthals. They were strong, made fine tools, hunted big animals, and survived the Ice Age. Farther east, live the mysterious Denisovans, known mainly from a cave in Siberia.
Meanwhile, in Africa, our own species appeared. The oldest Homo sapiens fossils from Jebel Irud in Morocco are about three hundred thousand years old. Around seventy thousand years ago, small groups of Homo sapiens spread out of Africa. They reached Australia by at least fifty thousand years ago, Europe by about forty five thousand, and finally crossed into the Americas more than fifteen thousand years ago.
Along the way, they met Neanderthals and Denisovans and had children together. That is why most people outside Africa still carry about one to two percent Neanderthal DNA. Our cousins disappeared around forty thousand years ago, but a part of them lives on in us.
So, how did these early humans actually live? Most lived in small bands of about twenty to fifty people, mostly family and friends. They moved with the seasons, gathering fruits, nuts, roots, and honey, and hunting or fishing. In many groups, gathered plants provided most of the food, and food was shared because in a small band, sharing meant survival.
They also cared for each other. At Shanidar Cave in Iraq, archaeologists found a Neanderthal man who had lost the use of one arm and was partly blind, yet he lived for years. Someone must have looked after him.
Then came art. At Blombos Cave in South Africa, people made shell beads and engraved ochre about seventy five thousand years ago. In Indonesia, a cave painting of people and a pig is more than fifty one thousand years old. Later came the great painted caves of Europe and the rock shelters of Bimbetka in India.
Life was hard. Many babies did not survive childhood, so the average lifespan was only around thirty. But those who made it past childhood could often live to fifty or sixty, passing their knowledge onto the young.
Then, about twelve thousand years ago, everything changed. In the fertile crescent of the Middle East, people began to farm. Soon, farming arose in China, India, Africa, and the Americas too. People settled in villages, then towns, and the modern world began.
From a small African ape to eight billion people, our story took seven million years, and every one of us carries a little of it in our bones, in our DNA, and in our curiosity.
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