Sapiens and Homo Deus

by Yuval Noah Harari

  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

  Exactly the same evolutionary logic shapes the lives of pigs, sows and piglets in human-controlled farms. In order to survive and reproduce in the wild, ancient boars needed to roam vast territories, familiarise themselves with their environment and beware of traps and predators. They further needed to communicate and cooperate with their fellow boars, forming complex groups dominated by old and experienced matriarchs. Evolutionary pressures consequently made wild boars – and even more so wild sows – highly intelligent social animals, characterised by a lively curiosity and strong urges to socialise, play, wander about and explore their surroundings. A sow born with some rare mutation that made her indifferent to her environment and to other boars was unlikely to survive or reproduce.

  The descendants of wild boars – domesticated pigs – inherited their intelligence, curiosity and social skills.12 Like wild boars, domesticated pigs communicate using a rich variety of vocal and olfactory signals: mother sows recognise the unique squeaks of their piglets, whereas two-day-old piglets already differentiate their mother’s calls from those of other sows.13 Professor Stanley Curtis of the Pennsylvania State University trained two pigs – named Hamlet and Omelette – to control a special joystick with their snouts, and found that the pigs soon rivalled primates in learning and playing simple computer games.14

  Today most sows in industrial farms don’t play computer games. They are locked by their human masters in tiny gestation crates, usually measuring six and a half by two feet. The crates have a concrete floor and metal bars, and hardly allow the pregnant sows even to turn around or sleep on their side, never mind walk. After three and a half months in such conditions, the sows are moved to slightly wider crates, where they give birth and nurse their piglets. Whereas piglets would naturally suckle for ten to twenty weeks, in industrial farms they are forcibly weaned within two to four weeks, separated from their mother and shipped to be fattened and slaughtered. The mother is immediately impregnated again, and sent back to the gestation crate to start another cycle. The typical sow would go through five to ten such cycles before being slaughtered herself. In recent years the use of crates has been restricted in the European Union and some US states, but the crates are still commonly used in many other countries, and tens of millions of breeding sows pass almost their entire lives in them.

  The human farmers take care of everything the sow needs in order to survive and reproduce. She is given enough food, vaccinated against diseases, protected against the elements and artificially inseminated. From an objective perspective, the sow no longer needs to explore her surroundings, socialise with other pigs, bond with her piglets or even walk. But from a subjective perspective, the sow still feels very strong urges to do all of these things, and if these urges are not fulfilled she suffers greatly. Sows locked in gestation crates typically display acute frustration alternating with extreme despair.15

  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. Sows confined in gestation crates. These highly social and intelligent beings spend most of their lives in this condition, as if they were already sausages.

  13.© Balint Porneczi/Bloomberg via Getty Images.

  Organisms are Algorithms

  How can we be sure that animals such as pigs actually have a subjective world of needs, sensations and emotions? Aren’t we guilty of humanising animals, i.e., ascribing human qualities to non-human entities, like children believing that dolls feel love and anger?

  In fact, 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

  In recent decades life scientists have demonstrated that emotions are not some mysterious spiritual phenomenon that is useful just for writing poetry and composing symphonies. Rather, emotions are biochemical algorithms that are vital for the survival and reproduction of all mammals. What does this mean? Well, let’s begin by explaining what an algorithm is. This is of great importance not only because this key concept will reappear in many of the following chapters, but also because the twenty-first century will be dominated by algorithms. ‘Algorithm’ is arguably the single most important concept in our world. If we want to understand our life and our future, we should make every effort to understand what an algorithm is, and how algorithms are connected with emotions.

  An algorithm is a methodical set of steps that can be used to make calculations, resolve problems and reach decisions. An algorithm isn’t a particular calculation, but the method followed when making the calculation. For example, if you want to calculate the average between two numbers, you can use a simple algorithm. The algorithm says: ‘First step: add the two numbers together. Second step: divide the sum by two.’ When you enter the numbers 4 and 8, you get 6. When you enter 117 and 231, you get 174.

  A more complex example is a cooking recipe. An algorithm for preparing vegetable soup may tell us:

  1.Heat half a cup of oil in a pot.

  2.Finely chop four onions.

  3.Fry the onion until golden.

  4.Cut three potatoes into chunks and add to the pot.

  5.Slice a cabbage into strips and add to the pot.

  And so forth. You can follow the same algorithm dozens of times, each time using slightly different vegetables, and therefore getting a slightly different soup. But the algorithm remains the same.

  A recipe by itself cannot make soup. You need a person to read the recipe and follow the prescribed set of steps. But you can build a machine that embodies this algorithm and follows it automatically. Then you just need to provide the machine with water, electricity and vegetables – and it will prepare the soup by itself. There aren’t many soup machines around, but you are probably familiar with beverage vending machines. Such machines usually have a slot for coins, an opening for cups, and rows of buttons. The first row has buttons for coffee, tea and cocoa. The second row is marked: no sugar, one spoon of sugar, two spoons of sugar. The third row indicates milk, soya milk, no milk. A man approaches the machine, inserts a coin into the slot and presses the buttons marked ‘tea’, ‘one sugar’ and ‘milk’. The machine kicks into action, following a precise set of steps. It drops a tea bag into a cup, pours boiling water, adds a spoonful of sugar and milk, and ding! A nice cup of tea emerges. This is an algorithm.17

  Over the last few decades biologists have reached the firm conclusion that the man pressing the buttons and drinking the tea is also an algorithm. A much more complicated algorithm than the vending machine, no doubt, but still an algorithm. Humans are algorithms that produce not cups of tea, but copies of themselves (like a vending machine which, if you press the right combination of buttons, produces another vending machine).

  The algorithms controlling vending machines work through mechanical gears and electric circuits. The algorithms controlling humans work
through sensations, emotions and thoughts. And exactly the same kind of algorithms control pigs, baboons, otters and chickens. Consider, for example, the following survival problem: a baboon spots some bananas hanging on a tree, but also notices a lion lurking nearby. Should the baboon risk his life for those bananas?

  This boils down to a mathematical problem of calculating probabilities: the probability that the baboon will die of hunger if he does not eat the bananas, versus the probability that the lion will catch the baboon. In order to solve this problem the baboon needs to take into account a lot of data. How far am I from the bananas? How far away is the lion? How fast can I run? How fast can the lion run? Is the lion awake or asleep? Does the lion seem to be hungry or satiated? How many bananas are there? Are they big or small? Green or ripe? In addition to these external data, the baboon must also consider information about conditions within his own body. If he is starving, it makes sense to risk everything for those bananas, no matter the odds. In contrast, if he has just eaten, and the bananas are mere greed, why take any risks at all?

  In order to weigh and balance all these variables and probabilities, the baboon requires far more complicated algorithms than the ones controlling automatic vending machines. The prize for making correct calculations is correspondingly greater. The prize is the very survival of the baboon. A timid baboon – one whose algorithms overestimate dangers – will starve to death, and the genes that shaped these cowardly algorithms will perish with him. A rash baboon – one whose algorithms underestimate dangers – will fall prey to the lion, and his reckless genes will also fail to make it to the next generation. These algorithms undergo constant quality control by natural selection. Only animals that calculate probabilities correctly leave offspring behind.

  Yet this is all very abstract. How exactly does a baboon calculate probabilities? He certainly doesn’t draw a pencil from behind his ear, a notebook from a back pocket, and start computing running speeds and energy levels with a calculator. Rather, the baboon’s entire body is the calculator. What we call sensations and emotions are in fact algorithms. The baboon feels hunger, he feels fear and trembling at the sight of the lion, and he feels his mouth watering at the sight of the bananas. Within a split second, he experiences a storm of sensations, emotions and desires, which is nothing but the process of calculation. The result will appear as a feeling: the baboon will suddenly feel his spirit rising, his hairs standing on end, his muscles tensing, his chest expanding, and he will inhale a big breath, and ‘Forward! I can do it! To the bananas!’ Alternatively, he may be overcome by fear, his shoulders will droop, his stomach will turn, his legs will give way, and ‘Mama! A lion! Help!’ Sometimes the probabilities match so evenly that it is hard to decide. This too will manifest itself as a feeling. The baboon will feel confused and indecisive. ‘Yes . . . No . . . Yes . . . No . . . Damn! I don’t know what to do!’

  In order to transmit genes to the next generation, it is not enough to solve survival problems. Animals also need to solve reproduction problems too, and this depends on calculating probabilities. Natural selection evolved passion and disgust as quick algorithms for evaluating reproduction odds. Beauty means ‘good chances for having successful offspring’. When a woman sees a man and thinks, ‘Wow! He is gorgeous!’ and when a peahen sees a peacock and thinks, ‘Jesus! What a tail!’ they are doing something similar to the automatic vending machine. As light reflected from the male’s body hits their retinas, extremely powerful algorithms honed by millions of years of evolution kick in. Within a few milliseconds the algorithms convert tiny cues in the male’s external appearance into reproduction probabilities, and reach the conclusion: ‘In all likelihood, this is a very healthy and fertile male, with excellent genes. If I mate with him, my offspring are also likely to enjoy good health and excellent genes.’ Of course, this conclusion is not spelled out in words or numbers, but in the fiery itch of sexual attraction. Peahens, and most women, don’t make such calculations with pen and paper. They just feel them.

  Even Nobel laureates in economics make only a tiny fraction of their decisions using pen, paper and calculator; 99 per cent of our decisions – including the most important life choices concerning spouses, careers and habitats – are made by the highly refined algorithms we call sensations, emotions and desires.18

  Because these algorithms control the lives of all mammals and birds (and probably some reptiles and even fish), when humans, baboons and pigs feel fear, similar neurological processes take place in similar brain areas. It is therefore likely that frightened humans, frightened baboons and frightened pigs have similar experiences.19

  There are differences too, of course. Pigs don’t seem to experience the extremes of compassion and cruelty that characterise Homo sapiens, nor the sense of wonder that overwhelms a human gazing up at the infinitude of a starry sky. It is likely that there are also opposite examples, of swinish emotions unfamiliar to humans, but I cannot name any, for obvious reasons. However, one core emotion is apparently shared by all mammals: the mother–infant bond. Indeed, it gives mammals their name. The word ‘mammal’ comes from the Latin mamma, meaning breast. Mammal mothers love their offspring so much that they allow them to suckle from their body. Mammal youngsters, on their side, feel an overwhelming desire to bond with their mothers and stay near them. In the wild, piglets, calves and puppies that fail to bond with their mothers rarely survive for long. Until recently that was true of human children too. Conversely, a sow, cow or bitch that due to some rare mutation does not care about her young may live a long and comfortable life, but her genes will not pass to the next generation. The same logic is true among giraffes, bats, whales and porcupines. We can argue about other emotions, but since mammal youngsters cannot survive without motherly care, it is evident that motherly love and a strong mother–infant bond characterise all mammals.20

  14. A peacock and a man. When you look at these images, data on proportions, colours and sizes gets processed by your biochemical algorithms, causing you to feel attraction, repulsion or indifference.

  14.Left: © Bergserg/Shutterstock.com. Right: © s_bukley/Shutterstock.com.

  It took scientists many years to acknowledge this. Not long ago psychologists doubted the importance of the emotional bond between parents and children even among humans. In the first half of the twentieth century, and despite the influence of Freudian theories, the dominant behaviourist school argued that relations between parents and children were shaped by material feedback; that children needed mainly food, shelter and medical care; and that children bonded with their parents simply because the latter provide these material needs. Children who demanded warmth, hugs and kisses were thought to be ‘spoiled’. Childcare experts warned that children who were hugged and kissed by their parents would grow up to be needy, egotistical and insecure adults.21

  John Watson, a leading childcare authority in the 1920s, sternly advised parents, ‘Never hug and kiss [your children], never let them sit in your lap. If you must, kiss them once on the forehead when they say goodnight. Shake hands with them in the morning.’22 The popular magazine Infant Care explained that the secret of raising children is to maintain discipline and to provide the children’s material needs according to a strict daily schedule. A 1929 article instructed parents that if an infant cries out for food before the normal feeding time, ‘Do not hold him, nor rock him to stop his crying, and do not nurse him until the exact hour for the feeding comes. It will not hurt the baby, even the tiny baby, to cry.’23

  Only in the 1950s and 1960s did a growing consensus of experts abandon these strict behaviourist theories and acknowledge the central importance of emotional needs. In a series of famous (and shockingly cruel) experiments, the psychologist Harry Harlow separated infant monkeys from their mothers shortly after birth, and isolated them in small cages. When given a choice between a metal dummy-mother fitted with a milk bottle, and a soft cloth-covered dummy with no milk, the baby monkeys clung to the barren cloth mother for all they were worth.<
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  Those baby monkeys knew something that John Watson and the experts of Infant Care failed to realise: mammals can’t live on food alone. They need emotional bonds too. Millions of years of evolution preprogrammed the monkeys with an overwhelming desire for emotional bonding. Evolution also imprinted them with the assumption that emotional bonds are more likely to be formed with soft furry things than with hard and metallic objects. (This is also why small human children are far more likely to become attached to dolls, blankets and smelly rags than to cutlery, stones or wooden blocks.) The need for emotional bonds is so strong that Harlow’s baby monkeys abandoned the nourishing metal dummy and turned their attention to the only object that seemed capable of answering that need. Alas, the cloth-mother never responded to their affection and the little monkeys consequently suffered from severe psychological and social problems, and grew up to be neurotic and asocial adults.

  Today we look back with incomprehension at early twentieth-century child-rearing advice. How could experts fail to appreciate that children have emotional needs, and that their mental and physical health depends as much on providing for these needs as on food, shelter and medicines? Yet when it comes to other mammals we keep denying the obvious. Like John Watson and the Infant Care experts, farmers throughout history took care of the material needs of piglets, calves and kids, but tended to ignore their emotional needs. Thus both the meat and dairy industries are based on breaking the most fundamental emotional bond in the mammal kingdom. Farmers get their breeding sows and dairy cows impregnated again and again. Yet the piglets and calves are separated from their mother shortly after birth, and often pass their days without ever sucking at her teats or feeling the warm touch of her tongue and body. What Harry Harlow did to a few hundred monkeys, the meat and dairy industries are doing to billions of animals every year.24