An Edible History of Humanity (2 page)

As with maize, proto-farmers selected for other desirable characteristics in wheat, rice, and other cereals during the process
of domestication. A mutation in wheat causes the hard glumes that cover each grain to separate more easily, resulting in “self-threshing”
varieties. The individual grains are less well protected as a result, so this mutation is bad news in the wild. But it is
helpful to human farmers, since it makes it easier to separate the edible grains after beating sheaves of cut wheat on a stone
threshing floor. When grains were being plucked from the floor, small grains and those with glumes still attached would have
been passed over in favor of larger ones without glumes. This helped to propagate these helpful mutations.

Another trait common to many domesticated crops is the loss of seed dormancy, the natural timing mechanism that determines
when a seed germinates. Many seeds require specific stimuli, such as cold or light, before they will start growing, to ensure
that they only germinate under favorable circumstances. Seeds that remain dormant until after a cold spell, for example, will
not germinate in the autumn, but will wait until after the winter has passed. Human farmers would often like seeds to start
growing as soon as they are planted, however. Given a collection of seeds, some of which exhibit seed dormancy and some of
which do not, it is clear that those that start growing right away stand a better chance of being gathered and thus forming
the basis of the next crop. So any mutations that suppress seed dormancy will tend to be propagated.

Similarly, wild cereals germinate and ripen at different times. This ensures that whatever the pattern of rainfall, at least
some of the grains will mature to provide seeds for the following year. Harvesting an entire field of grain on the same day,
however, favors grains that are almost ripe at the time. Grains that are over-ripe or under-ripe will be less viable if sown
as seeds the following year. The effect is to reduce the variation in ripening time from one year to the next, so that eventually
the entire field ripens at the same time. This is bad from the plant’s point of view, since it means the entire crop can potentially
fail. But it is far more con ve nient for human farmers.

In the case of rice, human intervention helped to propagate desirable properties such as taller and larger plants to aid harvesting,
and more secondary branches and larger grains to increase yield. But domestication also made wheat and rice more dependent
on human intervention. Rice lost its natural ability to survive in flood waters, for example, as it was pampered by human
farmers. And both wheat and rice were less able to reproduce by themselves because of the human-selected shatterproof rachis.
The domestication of wheat, rice, and maize, the three main cereal grains, and of their lesser siblings barley, rye, oats,
and millet, were all variations on the same familiar genetic theme: more convenient food, less resilient plant.

The same trade-off occurred as humans domesticated animals for the purpose of providing food, starting with sheep and goats
in the Near East around 8000 B.C. and followed by cattle and pigs soon afterward. (Pigs were independently domesticated in
China at roughly the same time, and the chicken was domesticated in southeast Asia around 6000 B.C.) Most domesticated animals
have smaller brains and less acute eyesight and hearing than their wild ancestors. This reduces their ability to survive in
the wild but makes them more docile, which suits human farmers.

Humans became dependent on their new creations, and vice versa. By providing a more dependable and plentiful food supply,
farming provided the basis for new lifestyles and far more complex societies. These cultures relied on a range of foods, but
the most important were the cereals: wheat and barley in the Near East, rice and millet in Asia, and maize in the Americas.
The civilizations that subsequently arose on these edible foundations, including our own, owe their existence to these ancient
products of genetic engineering.

This debt is acknowledged in many myths and legends in which the creation of the world, and the emergence of civilization
after a long period of barbarism, are closely bound up with these vital crops. The Aztecs of Mexico, for example, believed
men were created five times, each generation being an improvement over the last. Teosinte was said to have been man’s principal
food in the third and fourth creations. Finally, in the fifth creation, man nourished himself with maize. Only then did he
prosper, and his descendants populated the world.

The creation story of the Maya of southern Mexico, recounted in the Popul Vuh (or “sacred book”), also involves repeated attempts
to create mankind. At first the gods fashioned men out of mud, but the resulting creatures could barely see, could not move
at all, and were soon washed away. So the gods tried again, this time making men out of wood. These creatures could walk on
all fours and speak, but they lacked blood and souls, and they failed to honor the gods. The gods destroyed these men, too,
so that all that remained of them were a few tree-dwelling monkeys. Finally, after much discussion about the appropriate choice
of ingredients, the gods made a third generation of men from white and yellow ears of maize: “Of yellow maize and of white
maize they made their flesh; of corn-meal dough they made the arms and the legs of man. Only dough of corn-meal went into
the flesh of our first fathers, the four men, who were created.” The Maya believed they were descended from these four men
and their wives, who were created shortly afterward.

Maize also features in the story told by the Incas of South America to explain their origins. In ancient times, it is said,
the people around Lake Titicaca lived like wild animals. The sun god, Inti, took pity on them and sent his son Manco Capac
and his daughter Mama Ocllo, who were also husband and wife, to civilize them. Inti gave Manco Capac a golden stick with which
to test the fertility of the soil and its suitability for growing maize. Having found a suitable place, they were to found
a state and instruct its people in the proper worship of the sun god. The couple’s travels finally brought them to the Cuzco
Valley, where the golden stick disappeared into the ground. Manco Capac taught the people about farming and irrigation, Mama
Ocllo taught them about spinning and weaving, and the valley became the center of the Inca civilization. Maize was regarded
as a sacred crop by the Incas, even though potatoes also formed a large part of their diet.

Rice too appears in countless myths in the countries where it is grown. In Chinese myths, rice appears to save mankind when
it is on the verge of starvation. According to one story, the goddess Guan Yin took pity on the starving humans and squeezed
her breasts to produce milk, which flowed into the previously empty ears of the rice plants to become rice grains. She then
pressed harder, causing a mixture of blood and milk to flow into some of the plants. This is said to explain why rice exists
in both red and white varieties. Another Chinese tale tells of a great flood, after which very few animals remained for hunting.
As they searched for food, the people saw a dog coming toward them with bunches of long, yellow seeds hanging from its tail.
They planted the seeds, which grew into rice and dispelled their hunger forever. In a different series of rice myths, told
in Indonesia and throughout the islands of Indochina, rice appears as a delicate and virtuous maiden. The Indonesian rice
goddess, Sri, is the goddess of the earth who protects the people against hunger. One story tells how Sri was killed by the
other gods to protect her from the lecherous advances of the king of the gods, Batara Guru. When her body was buried, rice
sprouted from her eyes and sticky rice grew from her chest. Filled with remorse, Batara Guru gave these crops to mankind to
cultivate.

The tale of the creation of the world and the emergence of civilization told by the Sumerians, the ancient inhabitants of
what is now southern Iraq, refers to a time after the creation of the world by Anu, when people existed but agriculture was
unknown. Ashnan, the grain goddess, and Lahar, the goddess of sheep, had not yet appeared; Tagtug, patron of the craftsmen,
had not been born; and Mirsu, the god of irrigation, and Sumugan, the god of cattle, had not arrived to help mankind. As a
result, “the grain . . . and barley-grain for the cherished multitudes were not yet known.” Instead, the people ate grass
and drank water. The goddesses of grain and flocks were then created to provide food for the gods, but no matter how much
the gods ate, they were not filled. Only with the emergence of civilized men, who made regular offerings of food to the gods,
were the gods’ appetites finally satisfied. So domesticated crops and animals were a gift to man that conferred upon him an
obligation to make regular food offerings to the gods. This tale preserves a folk memory of a time before the adoption of
farming, when humans were still foragers. Similarly, a Sumerian hymn to the grain goddess describes a barbaric age before
cities, fields, sheepfolds, and cattle stalls—an era that came to an end when the grain goddess inaugurated a new era of civilization.

Contemporary explanations of the genetic basis of plant and animal domestication are really just the modern, scientific version
of these ancient and strikingly similar creation myths from around the world. Today, we would say that the abandonment of
hunting and gathering, the domestication of plants and animals, and the adoption of a settled lifestyle based on farming put
mankind on the road to the modern world, and that those earliest farmers were the first modern, “civilized” humans. Admittedly,
this is a rather less colorful account than those provided by the various creation myths. But given that the domestication
of certain key cereal crops was an essential step toward the emergence of civilization, there is no doubt that these ancient
tales contain far more than just a grain of truth.

The mechanism by which plants and animals were domesticated may be understood, but that does little to explain the motivations
of the people in question. Quite why humans switched from hunting and gathering to farming is one of the oldest, most complex,
and most important questions in human history. It is mysterious because the switch made people significantly worse off, from
a nutritional perspective and in many other ways. Indeed, one anthropologist has described the adoption of farming as “the
worst mistake in the history of the human race.”

Compared with farming, being a hunter-gatherer was much more fun. Modern anthropologists who have spent time with surviving
hunter-gatherer groups report that even in the marginal areas where they are now forced to live, gathering food only accounts
for a small proportion of their time—far less than would be required to produce the same quantity of food via farming. The
!Kung Bushmen of the Kalahari, for example, typically spend twelve to nineteen hours a week collecting food, and the Hazda
nomads of Tanzania spend less than fourteen hours. That leaves a lot of time free for leisure activities, socializing, and
so on. When asked by an anthropologist why his people had not adopted farming, one Bushman replied, “Why should we plant,
when there are so many mongongo nuts in the world?” (Mongongo fruits and nuts, which comprise around half the !Kung diet,
are gathered from wild stands of trees and are abundant even when no effort is made to propagate them.) In effect, hunter-gatherers
work two days a week and have five-day weekends.

The hunter-gatherer lifestyle in preagricultural times, in less marginal environments, would probably have been even more
pleasant. It used to be thought that the switch to farming gave people more time to devote to artistic pursuits, the development
of new crafts and technologies, and so on. Farming, in this view, was a liberation from the anxious hand-to-mouth existence
of the hunter-gatherer. But in fact the opposite turns out to be true. Farming is more productive in the sense that it produces
more food per unit of land: a group of twenty-five people can subsist by farming on a mere twenty-five acres, a much smaller
area than the tens of thousands of acres they would need to subsist by hunting and gathering. But farming is less productive
when measured by the amount of food produced per hour of labor. It is, in other words, much harder work.

Surely this effort was worthwhile if it meant that people no longer needed to worry about malnutrition or starvation? So you
might think. Yet hunter-gatherers actually seem to have been much healthier than the earliest farmers. According to the archaeological
evidence, farmers were more likely than hunter-gatherers to suffer from dental-enamel hypoplasia—a characteristic horizontal
striping of the teeth that indicates nutritional stress. Farming results in a less varied and less balanced diet than hunting
and gathering does. Bushmen eat around seventy-five different types of wild plants, rather than relying on a few staple crops.
Cereal grains provide reliable calories, but they do not contain the full range of essential nutrients.

So farmers were shorter than hunter-gatherers. This can be determined from skeletal remains by comparing the “dental” age
derived from the teeth with the “skeletal” age implied by the lengths of the long bones. A skeletal age that is lower than
the dental age is evidence of stunted growth due to malnutrition. Skeletal evidence from Greece and Turkey suggests that at
the end of the last ice age, around 14,000 years ago, the average height of hunter-gatherers was five feet nine inches for
men and five feet five inches for women. By 3000 B.C., after the adoption of farming, these averages had fallen to five feet
three inches for men and five feet for women. It is only in modern times that humans have regained the stature of ancient
hunter-gatherers, and only in the richest parts of the world. Modern Greeks and Turks are still shorter than their Stone Age
ancestors.

In addition, many diseases damage bones in characteristic ways, and evidence from studies of bones reveals that farmers suffered
from various diseases of malnutrition that were rare or absent in hunter-gatherers. These include rickets (vitamin D deficiency),
scurvy (vitamin C deficiency), and anemia (iron deficiency). Farmers were also more susceptible to infectious diseases such
as leprosy, tuberculosis, and malaria as a result of their settled lifestyles. And their dependence on cereal grains had other
specific consequences: female skeletons often display evidence of arthritic joints and deformities of the toes, knees, and
lower back, all of which are associated with the daily use of a saddle quern to grind grain. Dental remains show that farmers
suffered from tooth decay, unheard of in hunter-gatherers, because the carbohydrates in the farmers’ cereal-heavy diets were
reduced to sugars by enzymes in their saliva as they chewed. Life expectancy, which can also be determined from skeletons,
also fell: Evidence from the Illinois River Valley shows that average life expectancy at birth fell from twenty-six for hunter-gatherers
to nineteen for farmers.

At some archaeological sites it is possible to follow health trends as hunter-gatherers become more sedentary and eventually
adopt farming. As the farming groups settle down and grow larger, the incidence of malnutrition, parasitic diseases, and infectious
diseases increases. At other sites, it is possible to compare the condition of hunter-gatherers and farmers living alongside
each other. The settled farmers are invariably less healthy than their free-roaming neighbors. Farmers had to work much longer
and harder to produce a less varied and less nutritious diet, and they were far more prone to disease. Given all these drawbacks,
why on earth did people take up farming?

The short answer is that they did not realize what was happening until it was too late. The switch from hunting and gathering
to farming was a gradual one from the perspective of individual farmers, despite being very rapid within the grand scheme
of human history. For just as wild crops and domesticated crops occupy a continuum, there is a range from pure hunter-gatherer
to relying entirely on farmed foods.

Hunter-gatherers sometimes manipulate ecosystems to increase the availability of food, though such behavior falls far short
of the deliberate large-scale cultivation we call farming. Using fire to clear land and prompt new growth, for example, is
a practice that goes back at least 35,000 years. Australian aborigines, one of the few remaining groups of hunter-gatherers
to have survived into modern times, plant seeds on occasion to increase the availability of food when they return to a particular
site a few months later. It would be an exaggeration to call this farming, since such food makes up only a tiny fraction of
their diet. But the deliberate manipulation of the ecosystem means they are not exclusively hunter-gatherers either.

The adoption of farming seems to have happened as people moved gradually along the spectrum from being pure hunter-gatherers
to being ever more reliant on (and eventually dependent on) farmed food. Theories to explain this shift abound, but there
was probably no single cause. Instead a combination of factors were probably involved, each of which played a greater or lesser
role in each of the homelands where agriculture arose independently.

One of the most important factors appears to have been climate change. Studies of the ancient climate, based on the analysis
of ice cores, deep-sea cores, and pollen profiles, have found that between 18,000 B.C. and 9500 B.C. the climate was cold,
dry, and highly variable, so any attempt to cultivate or domesticate plants would have failed. Intriguingly there is evidence
of at least one such attempt, at a site called Abu Hureyra in northern Syria. Around 10,700 B.C. the inhabitants of this site
seem to have begun to domesticate rye. But their attempt fell victim to a sudden cold phase known as the Younger Dryas, which
began around 10,700 B.C. and lasted for around 1,200 years. Then, around 9500 B.C., the climate suddenly became warmer, wetter,
and more stable. This provided a necessary but not sufficient condition for agriculture. After all, if the newly stable climate
was the only factor that prompted the adoption of farming, then people would have adopted it simultaneously all around the
world. But they did not, so there must have been other forces at work as well.

One such factor was greater sedentism, as hunter-gatherers in some parts of the world became less mobile and began to spend
most of the year at a single camp, or even took up permanent residence. There are many examples of sedentary village communities
that predate the adoption of farming, such as those of the Natufian culture of the Near East, which flourished in the millennium
before the Younger Dryas, and others on the north coast of Peru and in North America’s Pacific Northwest. In each case these
settlements were made possible by abundant local wild food, often in the form of fish or shellfish. Normally, hunter-gatherers
move their camps to prevent the food supply in a particular area from becoming depleted, or to take advantage of the seasonal
availability of different foods. But there is no need to move around if you settle next to a river and the food comes to you.
Improvements in food-gathering techniques in the late Stone Age, such as better arrows, nets, and fish hooks, may also have
promoted sedentism. Once a hunter-gatherer band could extract more food (such as fish, small rodents, or shellfish) from its
surroundings, it did not need to move around so much.

Sedentism does not always lead to farming, and some settled hunter-gatherer groups survived into modern times without ever
adopting agriculture. But sedentism does make the switch to farming more likely. Settled hunter-gatherers who gather wild
grains, for example, might be inclined to start planting a few seeds in order to maintain the supply. Planting might also
have provided a form of insurance against variations in the supply of other foods. And since grains are processed using grinding
stones which are inconvenient for hunter-gatherers to carry from one camp to another, greater sedentism would have made grains
a more attractive foodstuff. The fact that grains are energy-rich, and could be dried and stored for long periods, also counted
in their favor. They were not a terribly exciting foodstuff, but they could be relied upon in extremis.

It is not hard to imagine how sedentary hunter-gatherers might have started to rely more heavily on cereal grains as part
of their diet. What was initially a relatively unimportant food gradually became more important, for the simple reason that
proto-farmers could ensure its availability (by planting and subsequent storage) in ways they could not for other foods. Archaeological
evidence from the Near East suggests that proto-farmers initially cultivated whatever wild cereals were at hand, such as einkorn
wheat. But as they became more reliant on cereals they switched to more productive crops, such as emmer wheat, which produce
more food for a given amount of labor.

Population growth as a result of sedentism has also been suggested as a contributory factor in the adoption of farming. Nomadic
hunter-gatherers have to carry everything with them when they move camp, including infants. Only when a child can walk unaided
over long distances, at the age of three of four, can its mother contemplate having another baby. Women in settled communities,
however, do not face this problem and can therefore have more children. This would have placed greater demands on the local
food supply and might have encouraged supplemental planting and, eventually, agriculture. One drawback with this line of argument,
however, is that in some parts of the world the population density appears to have increased significantly only after the
adoption of farming, not beforehand.

There are many other theories. In some parts of the world hunter-gatherers may have turned to farming as the big-game species
that were their preferred prey declined in number. Farming may have been prompted by social competition, as rival groups competed
to host the most lavish feasts; this might explain why, in some parts of the world, luxury foods appear to have been domesticated
before staples. Or perhaps the inspiration was religious, and people planted seeds as a fertility rite, or to appease the
gods after harvesting wild grains. It has even been suggested that the accidental fermentation of cereal grains, and the resulting
discovery of beer, provided the incentive for the adoption of farming, in order to guarantee a regular supply.

The important thing is that at no point did anyone make a conscious decision to adopt an entirely new lifestyle. At every
step along the way, people simply did what made the most sense at the time: Why be a nomad when you can settle down near a
good supply of fish? If wild food sources cannot be relied upon, why not plant a few seeds to increase the supply? The proto-farmers’
slowly increasing dependence on cultivated food took the form of a gradual shift, not a sudden change. But at some point an
imperceptible line was crossed, and people began to become dependent on farming. The line is crossed when the wild food resources
in the surrounding area, were they to be fully exploited, are no longer enough to sustain the population. The deliberate production
of supplementary food through farming is then no longer optional, but has become compulsory. At this point there is no going
back to a nomadic, hunter-gatherer lifestyle—or not, at least, without significant loss of life.

Farming then poses a second puzzle. Once agriculture had taken root in a few parts of the world, the question then becomes:
Why did it spread almost everywhere else? One possibility is that farmers spread out, displacing or exterminating hunter-gatherers
as they went. Alternatively, hunter-gatherers on the fringes of farming areas might have decided to follow suit and become
farmers themselves, adopting the methods and the domesticated crops and animals of their farming neighbors. These two possibilities
are known as “demic diffusion” and “cultural diffusion” respectively. So was it the actual farmers or merely the idea of farming
that spread?