Unstoppable Us, Volume 1: How Humans Took Over the World

When Sapiens migrated out of Africa 70,000 years ago, they went on foot. They developed rafts and canoes once they reached Asia’s coast and were able to populate the whole planet. About 50,000 years ago, they landed in Australia, which was full of megafauna, like a kangaroo that weighed more than 400 pounds and was six feet tall; giant snakes and koalas; and large, flightless birds called genyoris. All these animals became extinct after humans arrived in Australia because Sapiens cooperated in hunting them and unknowingly depleted their populations over time. These animals, which had never seen humans before, did not know to fear them. Humans’ ability to make fire worked to their advantage because they could burn down a densely forested area full of animals and then trap them. Humans similarly depleted the megafauna population on the American continents. 

Humans migrated from Siberia to North America on foot due to low sea levels, and they cooperated in large groups to survive the freezing northern winters by developing needles and sewing furs together to make warm clothing that could withstand the elements: “If ancient Sapiens hadn’t invented needles, they probably couldn’t have reached America” (158). These humans rapidly adapted to new climates and environments as they spread out, learning all they could about local plants, topography, and animals: “[A]nd then they invented new tricks, developed new tools, and adapted to the new conditions” (160).