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Summary
Themes
Key
LitCharts assigns a color and icon to each theme in Sapiens, which you can use to track the themes throughout the work.
Foraging, Industry, and Human Happiness
Fiction, Cooperation, and Culture
Science, Wealth, and Empire
Human-Caused Ecological Devastation
Summary
Analysis
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.
Harari begins by outlining the timeline he’ll address in the chapters that follow. He plans to explore what changed each time something revolutionized the way humans function in the world. He thinks that the Cognitive Revolution happened when ancient humans evolved advanced mental abilities—specifically, when they learned how to make up stories. The Agricultural Revolution happened when humans learned how to farm, and the Scientific Revolution happened when humans realized they could discover facts about the world by observing it rather than just turning to religious scriptures to understand the world around them. Harari will soon show that he’s skeptical about whether the agricultural and scientific revolutions actually improved life for humanity.
Themes
When animals produce fertile offspring, biologists classify them as the same “species.” Horses and donkeys are different species because they produce sterile mules. Poodles and terriers, however, are genetically similar enough to successfully interbreed, so they’re the same species (dog). 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.
Harari makes it clear that humans are animals—just like all other animals on Earth. He wants to show that there’s nothing inherently special or different about humans that sets us apart from other animals, because later, he will question why humans treat other animals so badly. To Harari, many people assume that humans are separate from (and fundamentally superior to) other animals in nature, so we’re justified in subjugating them. Harari, in contrast, stresses that humans are animals too, and it’s a shame that we should treat other similar beings so poorly.
Themes
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.
Harari wants to debunk the idea that humans are completely separate from the rest of the animal kingdom, and therefore entitled to dominate the planet’s ecosystem. He stresses that our ancestors weren’t unique: they were one of several human species, all of whom were animals too. Harari subtly implies that over the course of history, Homo sapiens systematically killed off other large mammals—starting with other human species—and he thinks this behavior is criminalizing.
Themes
Human species have very large brains for our bodies (though Neanderthal brains were the biggest). We tend to assume big brains are better, but scientists don’t actually know why they evolved. Human brains use up 25% of our energy, leaving less resources for other parts of our bodies like muscles, so our muscles are relatively weak compared to other mammals’ muscles. Chimpanzees, for example, can easily rip us apart. Humans are also the only mammals to walk upright, which frees our arms for other purposes. Harari speculates that fine-tuned muscular control of our hands evolved because it gave us the ability to make hand signals and tools, which probably helped us survive in ancient times.
Harari shows that all human species are physically weak: if it came down to a one-on-one brawl with another large mammal, (say, a chimpanzee), humans would easily lose. This means that it wasn’t ancient humans’ physical capabilities that enabled them to jump to the top of the food chain, but something to do with humans’ brain power. He hints that advanced cognitive capabilities (centering around communicating) had a lot to do with humans’ rise to the top.
Themes
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Walking upright also comes at a cost. Upright bodies can only accommodate narrow birth canals, increasing the risk of dying during childbirth. Wider birth canals also allow other mammals’ offspring to develop more fully in the womb. In contrast, human babies are born relatively prematurely (so they can fit through the birth canal), and they require years of care to become self-sufficient. Evolution thus favored social humans because they tended to outlive antisocial humans (it’s much harder for a lone human to successfully forage for food while also tending to offspring). Because human brains aren’t fully developed when we’re born, we’re also much more receptive to learning and education than other mammals.
Harari thinks that because humans are born with relatively undeveloped brains, we can be molded by exposure to information outside the womb. Later, he’ll suggest that the human ability to learn and believe new information (specifically, fictional or imagined stories about how the world works) played central role in enabling humans to advance so far as animals. In bringing up social versus. antisocial humans, he suggests that cooperation (i.e., social behavior) also helped ancient humans to thrive.
Themes
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. Ancient humans likely survived on the abandoned leftovers from other predators—by using tools to crack open bones and eat the marrow inside. 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.
Harari stresses that humans spent millions of years scraping by in the middle of the food chain. He wants to emphasize, as before, that humans are just animals, like all the other animals on Earth, in order to question why we treat other animals so badly. Harari also thinks that a chance event (a genetic mutation that changed the way humans used their brains) catapulted humans to the top of the food chain very suddenly. This means that it’s just a matter of blind chance (not destiny) that humans began dominating in nature—so we shouldn’t be too arrogant about our supposed superiority over other animals.
Themes
Other animal rose in the food chain over millions of years, allowing their ecosystems to calibrate around them so that those animals didn’t wreak havoc on their environments. Gazelles, for example, evolved to run faster as lions grew deadlier. Earth’s ecosystem didn’t have as much time to adjust for humans, because we rose to the top of the food chain so suddenly. We also didn’t have enough evolutionary time to evolve past the inherent fear and anxiety that help prey stay alert to predators. Harari thinks our fearful dispositions make us “doubly cruel and dangerous,” causing many “historical calamities, from deadly wars to ecological catastrophes.”
Harari thinks that humans’ innate fear of more fearsome predators originally helped ancient humans survive in the wild by alerting them to threats and enabling them to either fight or flee. Harari thinks this fear-based instinct still lingers in modern humans. He argues that it motivates us to cruelly subjugate all other creatures in nature, and often each other as well, which leads to disastrous results like wars. Harari also thinks the innate fear of predators manifests in modern humans as stress and anxiety, which makes us deeply unhappy. He'll expand more on this idea as the book goes on.
Themes
Scientists think the domestication of fire had a lot to do with humans’ rise to the top. Some human species used fire as early as 800,000 years ago. By 300,000 years ago, Homo erectus and Neanderthals regularly used fire. It provided a reliable source of warmth and light, and a weapon against predators. It also enabled cooking, which allowed human species to eat many things that can’t be consumed raw, like wheat, and digest food much more quickly while using less energy. Scientists think the advent of cooking allowed humans to evolve shorter intestines, smaller teeth and jaws, and bigger brains. Harari thinks the domestication of fire was “a sign of things to come.”
Harari uses the example of fire to show that when humans acquire a new skill or tool (as our ancestors did when they learned how to control and use fire) we tend to use it to relentlessly dominate in our habitat. It might seem like this is a good thing (using fire enabled humans to protect themselves from predators, for example) but Harari doesn’t think so. When Harari hints about “things to come,” he subtly suggests that humans tend to use the tools at our disposal selfishly, and we rarely think about the long-term effects of the damage we cause.
Themes
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. The “Interbreeding Theory” argues that sapiens bred with each other local human species as they spread, meaning that Eurasians were part Sapiens, part Neanderthals, while East Asians were part Sapiens, part Erectus. The “Replacement Theory” argues that interbreeding between different human species would have produced sterile offspring, meaning Sapiens either outlived or killed all other human species, meaning we’re all 100 percent Homo sapiens. Replacement Theory is more popular, partly because it claims that all races are genetically identical, thereby discouraging racism.
Harari shows that scientists often disagree about the data they collect, and they often attempt to piece together theories based on sparse data. He suggests that science is full of speculation: when scientists try to say something about what happened to the other human species that disappeared (like Neanderthals), the same data yields two conflicting theories. Harari often emphasizes that there’s a lot of guesswork involved in scientific theorizing because he doesn’t think science is that reliable, and he wants to encourage the reader to be somewhat skeptical about science, too, especially when there isn’t much data to go off.
Themes
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.
Harari shows how new data often exposes scientific claims as wrong, thus further emphasizing that there’s a great deal of speculation in scientific theorizing. He thinks the data suggests that ancient humans drove other human species to extinction. Harari even suggests that Homo sapiens may have intentionally massacred them. He wants to emphasize that Homo sapiens are an inherently violent and deadly species that tends to kill off other large mammals when they spread to new territory—even species that are very similar to themselves.
Themes
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).
Hariri emphasizes, once more, that humans aren’t special or different from other animals. Harari thinks that humans were propelled to the top of the food chain by chance, but to him, that’s not necessarily a good thing. He laments Homo sapiens’ tendency to cause widespread extinctions in every ecosystem they inhabit, because he thinks it leads to tremendous losses for humanity—both in the past, and in the modern day.
Themes
