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LitCharts | September 27 2024
The Big Bang happened 14 billion years ago, creating everything. About 300,000 years later, matter began clumping together into atoms, molecules, and complex structures. Then, 70,000 years ago, humans began forming more complex structures: cultures. Three important cultural “revolutions” happened since then: the Cognitive Revolution (70,000 years ago), the Agricultural Revolution (12,000 years ago), and the Scientific Revolution (500 years ago). Before these “revolutions,” human-like animals roamed the planet for 2.5 million years. Their social relations resembled ours today: including worried mothers, combative teenagers, and weary elders. Yet, they were insignificant animals, like all others on Earth
When animals produce fertile offspring, biologists classify them as the same “species.” Horses and donkeys are different species because they produce sterile mules. If species share a common ancestor, biologists say they come from the same “genus.” Humans are “Homo sapiens.” Our species is “sapiens” (wise), and we come from the genus “Homo” (human). All Homo species evolved from the Southern Ape. About 6 million years ago, a Southern Ape gave birth to two children. One of those children became the ancestor of all chimpanzees. The other became the ancestor of all Homo (human) species.
So far, scientists know about six different human species. Homo neanderthalsis (Neanderthals) thrived in Eurasia during the last Ice Age. Homo soloensis lived in Java, Indonesia. Homo erectus (“upright man”) survived in Eastern Asia for almost two million years. Scientists also discovered Homo floresienis (a dwarf human species) on Flores island, Indonesia, Homo denisova in Siberia, and Homo ergaster (“working man”). Many other as yet unknown human species may also have existed. Scientists think that from about 2 million years ago until 10,000 years ago, at least six human species were alive at the same time on Earth. Harari thinks that since no other human species exists today “incriminates” our species, Homo sapiens
We tend to assume that our tools, learning abilities, and social dynamics make us superior to other animals, but we didn’t make much use of these abilities for almost 2 million years. Ancient humans were relatively “weak and marginal” foragers, especially when compared to other carnivores. Back then, we were near the middle of the food chain. Humans rose to the top of the food chain quite suddenly 100,000 years ago, with the rise of Homo sapiens.
Scientists don’t know when Homo sapiens evolved, though most agree that around 150,000 years ago, Homo sapiens were populous in Africa. 70,000 years ago, Homo sapiens began spreading into other regions. Two competing theories address what happened next were The “Interbreeding Theory” and The “Replacement Theory”
Replacement Theory is more popular, partly because it claims that all races are genetically identical, thereby discouraging racism. However, in 2010, geneticists discovered that up to four percent of Eurasian human DNA contains Neanderthal genes, while up to six percent of aboriginal Australian DNA contains Denisovan genes, suggesting that Sapiens did mate with other human species. It seems Neanderthals and Denisovans were genetically close enough to Sapiens to yield fertile offspring (suggesting that Sapiens, Neanderthals, and Denisovans were at the borderline point between being the same and different species). However, the percentages are so low that Sapiens likely dominated the other Homo species’ habitats and drove all other Homo species to extinction, but also mated with a tiny fraction of them. It’s also possible that Sapiens committed genocide and intentionally murdered the other Homo species.
A speculative reconstruction of a Neanderthal child.
Harari notes that we humans like to think of ourselves as unique. When Charles Darwin proposed that Homo sapiens are just another kind of animal, people were outraged. Some still deny it today. The truth is, however, that as Homo sapiens spread around the world, other human species went extinct. Harari wonders what kinds of cultures, political systems, and religions would have evolved if the other Homo species still coexisted with us. For the last 10,000 years, Sapiens have been the last surviving human species (that we know of).
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