Homo Deus: A Brief History of Tomorrow

by Yuval Noah Harari

When Epicurus defined happiness as the supreme good, he warned his disciples that it is hard work to be happy. Material achievements alone will not satisfy us for long. Indeed, the blind pursuit of money, fame and pleasure will only make us miserable. Epicurus recommended, for example, to eat and drink in moderation, and to curb one’s sexual appetites. In the long run, a deep friendship will make us more content than a frenzied orgy.

happiness depends on expectations rather than objective conditions. We don’t become satisfied by leading a peaceful and prosperous existence. Rather, we become satisfied when reality matches our expectations. The bad news is that as conditions improve, expectations balloon. Dramatic improvements in conditions, as humankind has experienced in recent decades, translate into greater expectations rather than greater contentment.

Perhaps the key to happiness is neither the race nor the gold medal, but rather combining the right doses of excitement and tranquillity; but most of us tend to jump all the way from stress to boredom and back, remaining as discontented with one as with the other.

Once you achieve a momentous breakthrough, you cannot restrict its use to healing and completely forbid using it for upgrading.

Precisely because we have some choice regarding the use of new technologies, we had better understand what is happening and make up our minds about it before it makes up our minds for us.

But history is full of big mistakes.

History is often shaped by exaggerated hopes.

The more we know, the less we can predict.

This is the paradox of historical knowledge. Knowledge that does not change behaviour is useless. But knowledge that changes behaviour quickly loses its relevance. The more data we have and the better we understand history, the faster history alters its course, and the faster our knowledge becomes outdated.

Each and every one of us has been born into a given historical reality, ruled by particular norms and values, and managed by a unique economic and political system. We take this reality for granted, thinking it is natural, inevitable and immutable. We forget that our world was created by an accidental chain of events, and that history shaped not only our technology, politics and society, but also our thoughts, fears and dreams.

The cold hand of the past emerges from the grave of our ancestors, grips us by the neck and directs our gaze towards a single future. We have felt that grip from the moment we were born, so we assume that it is a natural and inescapable part of who we are. Therefore we seldom try to shake ourselves free, and envision alternative futures.

If you start with a flawed ideal, you often appreciate its defects only when the ideal is close to realisation.

People are usually afraid of change because they fear the unknown. But the single greatest constant of history is that everything changes.

In most Semitic languages, ‘Eve’ means ‘snake’ or even ‘female snake’. The name of our ancestral biblical mother hides an archaic animist myth, according to which snakes are not our enemies, but our ancestors.9 Many animist cultures believe that humans descended from animals, including from snakes and other reptiles. Most Australian Aborigines believed that the Rainbow Serpent created the world. The Aranda and Dieri people maintain that their particular tribes originated from primordial lizards or snakes, which were transformed into humans.10 In fact, modern Westerners too think that they have evolved from reptiles. The brain of each and every one of us is built around a reptilian core, and the structure of our bodies is essentially that of modified reptiles.

The Bible, along with its belief in human distinctiveness, was one of the by-products of the Agricultural Revolution, which initiated a new phase in human–animal relations.

It is certainly true that all instincts, drives and emotions evolved in order to meet the evolutionary pressures of survival and reproduction.

Why do modern humans love sweets so much? Not because in the early twenty-first century we must gorge on ice cream and chocolate in order to survive. Rather, it is because when our Stone Age ancestors came across sweet fruit or honey, the most sensible thing to do was to eat as much of it as quickly as possible. Why do young men drive recklessly, get involved in violent arguments and hack confidential Internet sites? Because they are following ancient genetic decrees that might be useless and even counterproductive today, but that made good evolutionary sense 70,000 years ago. A young hunter who risked his life chasing a mammoth outshone all his competitors and won the hand of the local beauty, and we are now stuck with his macho genes.11

This is the basic lesson of evolutionary psychology: a need shaped thousands of generations ago continues to be felt subjectively even if it is no longer necessary for survival and reproduction in the present. Tragically, the Agricultural Revolution gave humans the power to ensure the survival and reproduction of domesticated animals while ignoring their subjective needs. 13.

attributing emotions to pigs doesn’t humanise them. It ‘mammalises’ them. For emotions are not a uniquely human quality – they are common to all mammals (as well as to all birds and probably to some reptiles and even fish). All mammals evolved emotional abilities and needs, and from the fact that pigs are mammals we can safely deduce that they have emotions.16

Why does the theory of evolution provoke such objections, whereas nobody seems to care about the theory of relativity or quantum mechanics? How come politicians don’t ask that kids be exposed to alternative theories about matter, energy, space and time? After all, Darwin’s ideas seem at first sight far less threatening than the monstrosities of Einstein and Werner Heisenberg.

The theory of evolution rests on the principle of the survival of the fittest, which is a clear and simple – not to say humdrum – idea. In contrast, the theory of relativity and quantum mechanics argue that you can twist time and space, that something can appear out of nothing, and that a cat can be both alive and dead at the same time. This makes a mockery of our common sense, yet nobody seeks to protect innocent schoolchildren from these scandalous ideas. Why?

The theory of relativity makes nobody angry, because it doesn’t contradict any of our cherished beliefs. Most people don’t care an iota whether space and time are absolute or relative. If you think it is possible to bend space and time, well, be my guest. Go ahead and bend them. What do I care? In contrast, Darwin has deprived us of our souls. If you really understand the theory of evolution, you understand that there is no soul. This is a terrifying thought not only to devout Christians and Muslims, but also to many secular people who don’t hold any clear religious dogma, but neverth...

From an evolutionary perspective, the closest thing we have to a human essence is our DNA, and the DNA molecule is the vehicle of mutation rather than the seat of eternity. This terrifies large numbers of people, who prefer to reject the theory of evolution rather than give up their souls.

Every subjective experience has two fundamental characteristics: sensation and desire.

One of the wonderful things about science is that when scientists don’t know something, they can try out all kinds of theories and conjectures, but in the end they can just admit their ignorance.

The value of money is not the only thing that might evaporate once people stop believing in it. The same can happen to laws, gods and even entire empires. One moment they are busy shaping the world, and the next moment they no longer exist. Zeus and Hera were once important powers in the Mediterranean basin, but today they lack any authority because nobody believes in them.

Most people are also happy to acknowledge that ancient Greek gods, evil empires and the values of alien cultures exist only in the imagination. Yet we don’t want to accept that our God, our nation or our values are mere fictions, because these are the things that give meaning to our lives. We want to believe that our lives have some objective meaning, and that our sacrifices matter to something beyond the stories in our head. Yet in truth the lives of most people have meaning only within the network of stories they tell one another.

Meaning is created when many people weave together a common network of stories. Why does a particular action – such as getting married in church, fasting on Ramadan or voting on election day – seem meaningful to me? Because my parents also think it is meaningful, as do my brothers, my neighbours, people in nearby cities and even the residents of far-off countries. And why do all these people think it is meaningful? Because their friends and neighbours also share the same view.

People constantly reinforce each other’s beliefs in a self-perpetuating loop. Each round of mutual confirmation tightens the web of meaning further, until you have little ch...

That’s how history unfolds. People weave a web of meaning, believe in it with all their heart, but sooner or later the web unravels, and when we look back we cannot understand how anybody could have taken it seriously. With hindsight, going on crusade in the hope of reaching Paradise sounds like utter madness. With hindsight, the Cold War seems even madder. How come thirty years ago people were willing to risk nuclear holocaust because of their belief in a communist paradise? A hundred years hence, our belief in democracy and human rights might look equally incomprehensible to our descendants.

Written language may have been conceived as a modest way of describing reality, but it gradually became a powerful way to reshape reality. When official reports collided with objective reality, it was often reality that had to give way.

Priests and scribes in ancient civilisations became accustomed to seeing documents as guidebooks for reality. At first, the texts told them about the reality of taxes, fields and granaries. But as the bureaucracy gained power, so the texts gained authority. Priests recorded not only lists of the god’s property, but also the god’s deeds, commandments and secrets. The resulting scriptures purported to describe reality in its entirety, and generations of scholars became accustomed to looking for all the answers in the pages of the Bible, the Qur’an or the Vedas.

Abraham Lincoln said you cannot deceive everybody all the time. Well, that’s wishful thinking. In practice, the power of human cooperation networks depends on a delicate balance between truth and fiction.

If you distort reality too much, it will weaken you, and you will not be able to compete against more clear-sighted rivals. On the other hand, you cannot organise masses of people effectively without relying on some fictional myths. So if you stick to unalloyed reality, without mixing any fiction with it, few people will follow you.

Really powerful human organisations – such as pharaonic Egypt, the European empires and the modern school system – are not necessarily clear-sighted. Much of their power rests on their ability to force their fictional beliefs on a submissive reality.

Even when scriptures mislead people about the true nature of reality, they can nevertheless retain their authority for thousands of years. For instance, the biblical perception of history is fundamentally flawed, yet it managed to spread throughout the world, and many millions still believe in it.

The Bible peddled a monotheistic theory of history, claiming that the world is governed by a single all-powerful deity, who cares above all else about me and my doings. If something good happens, it must be a reward for my good deeds. Any catastrophe must surely be punishment for my sins.

Like a child thinking that his parents are fighting because of him, the monotheist is convinced that the Persians are fighting the Babylonians because of him.

Similarly in many countries around the world, including the USA and the UK, witnesses in courts put their hand on a Bible when swearing to tell the truth, the whole truth and nothing but the truth. It’s ironic that they swear to tell the truth on a book brimming with so many fictions, myths and errors.

History isn’t a single narrative, but thousands of alternative narratives. Whenever we choose to tell one, we are also choosing to silence others.

Most of the misunderstandings regarding science and religion result from faulty definitions of religion. All too often people confuse religion with superstition, spirituality, belief in supernatural powers or belief in gods. Religion is none of these things. Religion cannot be equated with superstition, because most people are unlikely to call their most cherished beliefs ‘superstitions’. We always believe in ‘the truth’; only other people believe in superstitions.

Defining religion as ‘belief in gods’ is also problematic. We tend to say that a devout Christian is religious because she believes in God, whereas a fervent communist isn’t religious, because communism has no gods. However, religion is created by humans rather than by gods, and it is defined by its social function rather than by the existence of deities.

Religion is any all-encompassing story that confers superhuman legitimacy on human laws, norms and values. It legitimises human social structures by arguing that they reflect superhuman laws.

Religion asserts that we humans are subject to a system of moral laws that we did not invent and that we cannot change. A devout Jew would say that this is the system of moral laws created by God and revealed in the Bible. A Hindu would say that Brahma, Vishnu and Shiva created the laws, which were revealed to us humans in the Vedas. Other religions, from Buddhism and Daoism to communism, Nazism and liberalism, argue that the so-called superhuman laws are natural laws, and not the creation of this...

Followers of every religion are convinced that theirs alone is true.

Religion is a deal, whereas spirituality is a journey.

Religion gives a complete description of the world, and offers us a well-defined contract with predetermined goals. ‘God exists. He told us to behave in certain ways. If you obey God, you’ll be admitted to heaven. If you disobey Him, you’ll burn in hell.’ The very clarity of this deal allows society to define common norms and values that regulate human behaviour.

Such journeys are fundamentally different from religions, because religions seek to cement the worldly order whereas spirituality seeks to escape it.

In Zen Buddhism it is said that ‘If you meet the Buddha on the road, kill him.’ Which means that if while walking on the spiritual path you encounter the rigid ideas and fixed laws of institutionalised Buddhism, you must free yourself from them too.

Religion cannot provide us with any practical guidance unless it makes some factual claims too, and here it may well collide with science. The most important segments of many religious dogmas are not their ethical principles, but rather factual statements such as ‘God exists’, ‘the soul is punished for its sins in the afterlife’, ‘the Bible was written by a deity rather than by humans’, ‘the Pope is never wrong’. These are all factual claims. Many of the most heated religious debates, and many of the conflicts between science and religion, involve such factual claims rather than ethical judgements.