Sapiens: a brief History of Humankind

inter-subjective
is something that exists within the communication
network linking the subjective consciousness of many individuals. If a single
individual changes his or her beliefs, or even dies, it is of little importance.
However, if most individuals in the network die or change their beliefs, the inter-
subjective phenomenon will mutate or disappear. Inter-subjective phenomena are
neither malevolent frauds nor insigni cant charades. They exist in a di erent way
from physical phenomena such as radioactivity, but their impact on the world may
still be enormous. Many of history’s most important drivers are inter-subjective:
law, money, gods, nations.
Peugeot, for example, is not the imaginary friend of Peugeot’s CEO. The
company exists in the shared imagination of millions of people. The CEO believes
in the company’s existence because the board of directors also believes in it, as do
the company’s lawyers, the secretaries in the nearby o ce, the tellers in the bank,

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the brokers on the stock exchange, and car dealers from France to Australia. If the
CEO alone were suddenly to stop believing in Peugeot’s existence, he’d quickly
land in the nearest mental hospital and someone else would occupy his office.
Similarly, the dollar, human rights and the United States of America exist in the
shared imagination of billions, and no single individual can threaten their
existence. If I alone were to stop believing in the dollar, in human rights, or in the
United States, it wouldn’t much matter. These imagined orders are inter-
subjective, so in order to change them we must simultaneously change the
consciousness of billions of people, which is not easy. A change of such magnitude
can be accomplished only with the help of a complex organisation, such as a
political party, an ideological movement, or a religious cult. However, in order to
establish such complex organisations, it’s necessary to convince many strangers to
cooperate with one another. And this will happen only if these strangers believe
in some shared myths. It follows that in order to change an existing imagined
order, we must first believe in an alternative imagined order.
In order to dismantle Peugeot, for example, we need to imagine something
more powerful, such as the French legal system. In order to dismantle the French
legal system we need to imagine something even more powerful, such as the
French state. And if we would like to dismantle that too, we will have to imagine
something yet more powerful.
There is no way out of the imagined order. When we break down our prison
walls and run towards freedom, we are in fact running into the more spacious
exercise yard of a bigger prison.

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7
Memory Overload
EVOLUTION DID NOT ENDOW HUMANS with the ability to play football. True, it
produced legs for kicking, elbows for fouling and mouths for cursing, but all that
this enables us to do is perhaps practise penalty kicks by ourselves. To get into a
game with the strangers we nd in the schoolyard on any given afternoon, we not
only have to work in concert with ten teammates we may never have met before,
we also need to know that the eleven players on the opposing team are playing
by the same rules. Other animals that engage strangers in ritualised aggression do
so largely by instinct – puppies throughout the world have the rules for rough-and-
tumble play hard-wired into their genes. But human teenagers have no genes for
football. They can nevertheless play the game with complete strangers because
they have all learned an identical set of ideas about football. These ideas are
entirely imaginary, but if everyone shares them, we can all play the game.
The same applies, on a larger scale, to kingdoms, churches and trade networks,
with one important di erence. The rules of football are relatively simple and
concise, much like those necessary for cooperation in a forager band or small
village. Each player can easily store them in his brain and still have room for
songs, images and shopping lists. But large systems of cooperation that involve
not twenty-two but thousands or even millions of humans require the handling
and storage of huge amounts of information, much more than any single human
brain can contain and process.
The large societies found in some other species, such as ants and bees, are stable
and resilient because most of the information needed to sustain them is encoded in
the genome. A female honeybee larva can, for example, grow up to be either a
queen or a worker, depending on what food it is fed. Its DNA programmes the
necessary behaviours for whatever role it will ful l in life. Hives can be very
complex social structures, containing many di erent kinds of workers, such as
harvesters, nurses and cleaners. But so far researchers have failed to locate lawyer
bees. Bees don’t need lawyers, because there is no danger that they might forget
or violate the hive constitution. The queen does not cheat the cleaner bees of their
food, and they never go on strike demanding higher wages.
But humans do such things all the time. Because the Sapiens social order is

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imagined, humans cannot preserve the critical information for running it simply
by making copies of their DNA and passing these on to their progeny. A conscious
e ort has to be made to sustain laws, customs, procedures and manners, otherwise
the social order would quickly collapse. For example, King Hammurabi decreed
that people are divided into superiors, commoners and slaves. Unlike the beehive
class system, this is not a natural division – there is no trace of it in the human
genome. If the Babylonians could not keep this ‘truth’ in mind, their society would
have ceased to function. Similarly, when Hammurabi passed his DNA to his
o spring, it did not encode his ruling that a superior man who killed a commoner
woman must pay thirty silver shekels. Hammurabi deliberately had to instruct his
sons in the laws of his empire, and his sons and grandsons had to do the same.
Empires generate huge amounts of information. Beyond laws, empires have to
keep accounts of transactions and taxes, inventories of military supplies and
merchant vessels, and calendars of festivals and victories. For millions of years
people stored information in a single place – their brains. Unfortunately, the
human brain is not a good storage device for empire-sized databases, for three
main reasons.
First, its capacity is limited. True, some people have astonishing memories, and
in ancient times there were memory professionals who could store in their heads
the topographies of whole provinces and the law codes of entire states.
Nevertheless, there is a limit that even master mnemonists cannot transcend. A
lawyer might know by heart the entire law code of the Commonwealth of
Massachusetts, but not the details of every legal proceeding that took place in
Massachusetts from the Salem witch trials onward.
Secondly, humans die, and their brains die with them. Any information stored in
a brain will be erased in less than a century. It is, of course, possible to pass
memories from one brain to another, but after a few transmissions, the
information tends to get garbled or lost.
Thirdly and most importantly, the human brain has been adapted to store and
process only particular types of information. In order to survive, ancient hunter-
gatherers had to remember the shapes, qualities and behaviour patterns of
thousands of plant and animal species. They had to remember that a wrinkled
yellow mushroom growing in autumn under an elm tree is most probably
poisonous, whereas a similar-looking mushroom growing in winter under an oak
tree is a good stomach-ache remedy. Hunter-gatherers also had to bear in mind the
opinions and relations of several dozen band members. If Lucy needed a band
member’s help to get John to stop harassing her, it was important for her to
remember that John had fallen out last week with Mary, who would thus be a
likely and enthusiastic ally. Consequently, evolutionary pressures have adapted
the human brain to store immense quantities of botanical, zoological,

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topographical and social information.
But when particularly complex societies began to appear in the wake of the
Agricultural Revolution, a completely new type of information became vital –
numbers. Foragers were never obliged to handle large amounts of mathematical
data. No forager needed to remember, say, the number of fruit on each tree in the
forest. So human brains did not adapt to storing and processing numbers. Yet in
order to maintain a large kingdom, mathematical data was vital. It was never
enough to legislate laws and tell stories about guardian gods. One also had to
collect taxes. In order to tax hundreds of thousands of people, it was imperative to
collect data about peoples incomes and possessions; data about payments made;
data about arrears, debts and nes; data about discounts and exemptions. This
added up to millions of data bits, which had to be stored and processed. Without
this capacity, the state would never know what resources it had and what further
resources it could tap. When confronted with the need to memorise, recall and
handle all these numbers, most human brains overdosed or fell asleep.
This mental limitation severely constrained the size and complexity of human
collectives. When the amount of people and property in a particular society
crossed a critical threshold, it became necessary to store and process large
amounts of mathematical data. Since the human brain could not do it, the system
collapsed. For thousands of years after the Agricultural Revolution, human social
networks remained relatively small and simple.
The rst to overcome the problem were the ancient Sumerians, who lived in
southern Mesopotamia. There, a scorching sun beating upon rich muddy plains
produced plentiful harvests and prosperous towns. As the number of inhabitants
grew, so did the amount of information required to coordinate their a airs.
Between the years 3500 
BC
and 3000 
BC
, some unknown Sumerian geniuses
invented a system for storing and processing information outside their brains, one
that was custom-built to handle large amounts of mathematical data. The
Sumerians thereby released their social order from the limitations of the human
brain, opening the way for the appearance of cities, kingdoms and empires. The
data-processing system invented by the Sumerians is called ‘writing’.
Signed, Kushim
Writing is a method for storing information through material signs. The Sumerian
writing system did so by combining two types of signs, which were pressed in clay
tablets. One type of signs represented numbers. There were signs for 1, 10, 60,
600, 3,600 and 36,000. (The Sumerians used a combination of base-6 and base-10

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numeral systems. Their base-6 system bestowed on us several important legacies,
such as the division of the day into twenty-four hours and of the circle into 360
degrees.) The other type of signs represented people, animals, merchandise,
territories, dates and so forth. By combining both types of signs the Sumerians
were able to preserve far more data than any human brain could remember or
any DNA chain could encode.