Agriculture did not arise from need so much as it did from relative abundance. People stayed put, had the leisure to experiment with plants, lived in coastal zones where floods gave them the model of and denizens of disturbance, built up permanent settlements that increasingly created disturbance, and were able to support a higher birthrate because of sedentism.

In the Middle East, this conjunction of forces occurred about ten thousand years ago, an interesting period from another angle. That date, the start of what is called the Neolithic Revolution, also coincides closely with the end of the last glaciation. As I write this, I sit in a spot that was then at the bottom of a huge lake. I live in a valley that held a lake famous to geologists, glacial Lake Missoula. The valley was formed by an ice dam that sat a couple hundred miles from here, and as the glaciers melted, the ice dam broke and re-formed many times, each time draining in a few hours a body of water the size of today’s Lake Michigan. That’s disturbance. The record of these floods can be clearly read today in giant washes and blowouts throughout the Columbia River basin in Washington State. Within the mouth of the Columbia River, several hundred miles downstream, is a twenty-five-mile-long peninsula made of sand washed downstream in these floods.

When the glaciers retreated, such catastrophic events were happening with increased frequency in floodplains around the world, especially in the Middle East. Juris Zarins of the University of Missouri has suggested that these massive disturbances and floods underlie the central Old Testament myths—the great flood, but also the Garden of Eden. Following a specific description in Genesis of the site of Eden, Zarins traces what he speculates are the four rivers of the Tigris and Euphrates system mentioned there. They would have converged in what is now the Persian Gulf, but during glaciation this would have been dry land. Further, it would have been an enormously productive plain, the sort of place that would have naturally produced an abundance of food without farming.

We call it the Garden of Eden, but it was not a garden; it was not cultivated. In fact, in Genesis, God is vengeful and specific in throwing Adam and Eve out of paradise; his punishment is that they will begin gardening. Says God, “In the sweat of thy face shalt thou eat bread, till thou return unto the ground.” God made good on his threat, and the record now shows just how angry he was. The children of Adam and Eve would hoe rows of corn. “To condemn all of humankind to a life of full-time farming, and in particular, arable farming, was a curse indeed,” writes Colin Tudge.

At about the same time that the shapes of seeds and of butchered sheep bones were changing, so were the shapes of villages and graves. Grave goods—tools, weapons, food, and comforts—were by then nothing new in the ritual of human burials. There is even some evidence, albeit controversial, that Neanderthals, an extinct branch of the family, buried some of their dead with flowers. Burial ritual was certainly a part of hunter-gatherer life, but the advent of agriculture brought changes.

For instance, one of the world’s richest collections of early agricultural settlements lies in the rice wetlands of China’s Hupei basin on the upper Yangtze River. The region was home to the Ta-hsi culture that domesticated rice between 5,500 and 6,000 years ago. Excavation of 208 graves there found many empty of anything but the dead, while others were elaborately endowed with goods. The same pattern emerges worldwide, one of the key indicators that, for the first time in human history, some people were more highly regarded than others, that agriculture conferred social status—or, more important, more goods—to a few people.

Some of early agriculture’s graves contained headless corpses, corresponding to archaeologists finding skulls in odd places and conditions. Skulls in the Middle East, for instance, were plastered to floors or into special pits. Some of the skulls had been altered to appear older. Archaeologists take this as a sign of ancestor worship, reasoning that because of the permanent occupation of land, it became important to establish a family’s claim on the land, and veneration of ancestors was a part of that process. So, too, was a rise in the importance of the family as opposed to the entire tribe, a switch that further evidence bears out.

Coincident with this was a shift in the villages themselves. Small clutches of simple huts gave way to larger collections, but with a qualitative change as well. Some houses became larger than others. At the same time, storage bins, granaries, began to appear. Cultivated grain, more so than any form of food humans had consumed before, was storable, not just through the year, but from year to year. It is hard to overstate the importance of this simple fact as it would play out through the centuries, later making possible such developments as, for instance, the provisioning of armies. But the immediate effect of storage was to make wealth possible. The big granaries were associated with the big houses and the graves whose headless skeletons were endowed with a full complement of grave goods.

The Museum of Anatolian Civilizations in Ankara, Turkey, holds one of the world’s most impressive assemblages of early agricultural remnants, including a reconstruction of a grave from a nearby city once ruled over by King Midas. He was a real guy, and his region was indeed known for its wealth in gold, taken from the Pactolus River. Yet the grave unearthed at Gordium (home of the Gordian knot) once thought to be Midas’s (but now identified as that of another in his line) was not full of gold. It was full of storage vessels for grain.

Of course to assert that agriculture’s grain made wealth possible is to assert that it also created poverty, a notion that counters the just-so story. The popular contention is that agriculture was an advance, progress that enriched humanity. Whatever the quality of our lives as hunter-gatherers, our numbers had become such that hunger forced this efficiency. Or so the story goes.

We have seen that agriculture in fact arose from abundance. More important, wealth, as distinct from abundance, is one of those dichotomous ideas only understood in the presence of its opposite, poverty. If we are to seek ways in which humans differ from all other species, this dichotomy would head the list. This is not to say that hunter-gatherers did not experience need, hard times, even starvation, just as all other animals do. We would be hard-pressed, however, to find communities of any social animal except modern humans in which an individual in the community has access to fifty, a hundred, a thousand times, or even twice as many resources as another. Yet such communities are the rule among post-agricultural humans.

Some social animals do indeed have hierarchy. Chickens and wolves have a pecking order, elk a herd bull, and bees a queen. Yet the very fact that we call the reproductive female in a hive of bees the “queen” is an imposition on animals of our ideas of hierarchy. The queen doesn’t rule, nor does she have access to forty times more food than she needs; nor does the alpha male wolf. Among elk, the herd bull is the first to starve during a rough winter, because he uses all his energy reserves during the fall rut.

The notion that agriculture created poverty is not an abstraction, but one borne out by the archaeological record. Forget the headless skeletons; they represent the minority, the richest people. A close examination of the many, buried with heads and without grave goods, makes a far more interesting platform for the question of why agriculture. Another approach to this question would be to walk the ancient settlement of Cahokia, just outside of St. Louis, Missouri, and ask: Why all these mounds?

Cahokia was occupied until about six hundred years ago by the corn, squash, and bean culture of what is now the midwestern United States. There are a whole series of towns abandoned for no apparent reason just before the first Europeans arrived. “Mounds” understates the case, especially to those thinking the grand monuments of antiquity are part of the Old World’s lineage alone.

They are really dirt pyramids, a series of about a hundred, the largest rising close to a hundred feet high and nearly one thousand feet long on a side at its base. The only way to make such an enormous pile of dirt then was to carry it in baskets mounted on the backs of people, day in, day out, for lifetimes.

Much has been made of the creative forces that agriculture unleashed, and this is fair enough. Art, libraries, and literacy, are all agriculture’s legacy. But around the world, the first agricultural towns are marked by mounds, pyramids, temples, ziggurats, and great walls, all monuments reaching for the sky, the better to elevate the potentates in command of the construction. In each case, their command was a demonstration of enormous control over a huge force of stoop labor, often organized in one of civilization’s favorite institutions: slavery. The monuments are clear indication that, for a lot of people, life did not get better under agriculture, an observation particularly pronounced in Central America. There, the long steps leading to the pyramids’ tops are blood-stained, the elevation having been used for human sacrifice and the dramatic flinging of the victim down the long, steep steps.

Aside from its mounds, though, Cahokia is useful for considering the just-so story of agriculture’s emergence because it lies in the American Midwest, was relatively recent, and was largely contiguous and contemporaneous with surrounding hunter-gatherer territories. Like most agricultural societies, the mound builders coexisted with nomad hunters. Both groups were part of a broad trading network that brought copper from Michigan’s Upper Peninsula to what is now St. Louis, and seashells from the southeastern Atlantic Coast to Montana’s Sweet Grass Hills. This coexistence gives us a chance to compare lives by comparing skeletons.

We know from their remains that the farmers were smaller, the result of general deprivation and abuse. The women, especially, were smaller. The physiques that make up a modern women’s soccer or basketball team were simply unheard of among agricultural peoples, from farming’s beginnings to only very recent times. On average, we moderns (and only those of us in the richest parts of the world) are just beginning to regain the stature that we had as hunter-gatherers, who throughout time were on average as tall as North Americans are today.

Part of this decline stems from poor diet, especially for those who provided the stoop labor. Some of it is inherent in sedentism. Almost every locale’s soil and water are deficient in one mineral or another, a fact that was not a problem for nomadic hunter-gatherers. By moving about and taking food from a variety of niches, they balanced one locale’s deficiencies against another’s excess. This is also true for the early sedentary cities that relied on seafood. They didn’t move, but the fish did, bringing with them minerals from a wide range of places.

More important, however, grain’s availability as a cheap and easily stored package of carbohydrates made it the food of the poor. It allowed one to carry baskets of dirt day after day, but its lack of nutritional balance left people malnourished and stunted. The complex carbohydrates of grains are almost instantly reduced to sugars by digestion, sometimes simply from being chewed. The skeletal record of farming peoples shows this as tooth decay, an ailment nonexistent among contemporary hunter-gatherers.

That same grain, however, could be ground to soft, energy-rich gruels that had been unavailable to previous peoples, one of the more significant changes. The pelvises from female skeletons show evidence of having delivered more children than their counterparts in the wild. The availability of soft foods meant children could be weaned earlier—at one year instead of four. Women then could turn out the masses of children that would grow up to build pyramids and mounds.

They could also grind the grain. Theya Molleson of the Natural History Museum in London has found a common syndrome among these women’s skeletons: the toes and knees are bent and arthritic, and the lower back is deformed. She traces this to the saddle quern, a primitive stone rolling-pin mortar and pestle used for grinding grain. These particular deformities mark lives of days spent grinding.

The baseline against which these deformities and rotten teeth are measured is just as clear. For instance, paleopathologists who have studied skeletal remains of hunter-gatherers living in the diverse and productive systems of what is now central California found them “so healthy it is somewhat discouraging to work with them.” As many societies turned to agriculture in the early days, they did so only to supplement or stabilize a basic existence of hunting and gathering. Among these people, paleopathologists found few of the difficulties associated with people who are exclusively agricultural.

The marks of agriculture on subsequent groups, however, are unmistakable. In his book The Day Before America, William H. MacLeish summarizes the record of a group in the Ohio River valley: “Almost one-fifth of the Fort Ancient settlement dies during weaning. Infants suffer growth arrests indicating that at birth their mothers were undernourished and unable to nurse well. One out of a hundred individuals lives beyond fifty. Teeth rot. Iron deficiency, anemia, is widespread, as is an infection produced by treponemata” (a genus of bacteria that causes yaws and syphilis).

The inclusion here of communicable diseases is significant and consistent with the record worldwide. Sedentary people were often packed into dense, stable villages where diseases could get a foothold, particularly those diseases related to sanitation, like cholera and tuberculosis. Just as important, the early farmers domesticated livestock, which became sources of many of our major infectious diseases, like smallpox, influenza, measles, and the plague.

Summarizing evidence from around the world, researcher Mark Cohen ticks off a list of diseases and conditions evident in skeletal and fecal remains of early farmers but absent among hunter-gatherers. The list includes malnutrition, osteomyelitis and periostitis (bone infections), intestinal parasites, yaws, syphilis, leprosy, tuberculosis, anemia (from poor diet as well as from hookworms), rickets in children, osteomalacia in adults, retarded childhood growth, and short stature among adults.

Such ills were obviously hard on the individual, as were the slavery, poverty, and oppression agriculture seems to have brought with it. And all of this seems to take us further from answering the question: Why agriculture? Remember, though, that this is an evolutionary question.

The question of agriculture can easily get tangled in values, as it should. Farming was the fundamental determinant of the quality (or lack thereof) of human life for the past ten thousand years. It made us, and makes us, what we are. We have long assumed that this fundamental technology was progress, and that progress implies an improvement in the human condition. Yet framing the question this way has no meaning. Biology and evolution don’t care very much about quality of life. What counts is persistence, or, more appropriately, endurance—a better word in that it layers meanings: to endure as a species, we endure some hardships. What counts to biology is a species’ success, defined as its members living long enough to reproduce robustly, to be fruitful and multiply. Clearly, farming abetted that process. We learned to grow food in dense, portable packages, so our societies could become dense and portable.

We were not alone in this. Estimates say our species alone uses forty percent of the primary productivity of the planet. That is, of all the solar energy striking the surface, almost half flows through our food chain—almost half to feed a single species among millions extant. That, however, overstates the case, in that a select few plants (wheat, rice, and corn especially) and a select few domestic animals (cattle, chickens, goats, and sheep for the most part, and, as a special case, dogs) are also the beneficiaries of human ubiquity. We and these species are a coalition, and the coalition as a whole plays by the biological rules. Six or so thousand years ago, some wild sheep and goats cut a deal in the Zagros Mountains of what is now Turkey. A few began hanging around the by-then longtime wheat farmers and barley growers of the Middle East. The animals’ bodies, their skeletal remains, show this transition much as the human bones do: they are smaller, more diseased, more battered and beaten, but they are more numerous, and that’s what counts. By cutting this deal, the animals suffer the abuses of society, but today they are among the most numerous and widespread species on the planet, along with us and our food crops.

Simultaneously, a whole second order of creatures—freeloaders and parasites—were cutting the same deal. Our crowding and our proximity to a few species of domestic animals gave microorganisms the laboratory they needed to develop more virulent, more enduring, and more portable configurations, and they are with us in this way today, also fruitful and multiplied. At the same time, the ecological disturbance that was a precondition of agriculture opened an ever broadening niche, not just for our domestic crops, but for a slew of wild plants that had been relegated to a narrow range. Domesticated cereals, squashes, and chenopods are not the only plants adapted to catastrophes like flood and fire. There is a range of early succession colonizers, a class of life we commonly call weeds. They are an integral part of the coalition and, as we shall see, almost as important as our evolved diseases in allowing the coalition to spread.

In all of this we can see the phenomenon that biologists call coevolution. In the waxing and waning of species that characterizes all of biological time, change does not occur in isolation. Species changeto respond to change in other species. Coalitions form. Domestication was such a change. Human selection pressure on crops and animals can be read so clearly in the archaeological record because the archaeological record is a reflection of the genetic record. We re-formed the genome of the plants just as surely as (and more significantly than) any of the most Frankensteinian projects of genetic manipulation plotted by today’s biotechnologists. The shape of life changed.

Can the same be said of the domesticates’ effects on us? Did they reengineer humans? After all, we can see the change in the human body clearly written in the archaeological record. Or at least we can if for a second we allow ourselves to lapse into Lamarckianism. In 1809, Jean-Baptiste Lamarck set forth a pre-Darwinian theory of evolution that suggested that environmentally conditioned changes in an individual would be inherited by the subsequent generations. That is, to put it in modern terms, conditioning changes the genome. This would imply that a spaniel with a docked tail would spawn stub-tailed progeny, or that a weightlifter’s children would emerge from the womb with bulging biceps. We know this is false. (Mostly we know—there are some valid neo-Lamarckian arguments.) Many of the changes in humans I’ve cited above are in fact responses to the changing conditions brought on by agriculture: the malnutrition, disease, and deformed bones were not inherited, but battered into place with each new generation.

These changes are the result of cultural, not biological, evolution. Do not discount such changes as unimportant; culture evolves as surely—and as inexorably and anarchically—as do our bodies, and it does indeed have enormous effect on our quality of life. Poverty is a direct result of cultural evolution, and despite ten thousand years of railing and warning against it, the result is still, as Christ predicted, that the poor are always with us.

By bringing this distinction between biological and cultural evolution into play, I mean to set a higher hurdle for the argument that agriculture was a powerful enough leap in technology to be read in our genome. Agriculture was social evolution, but at the same time it also instigated genuine biological evolution in humans.

Take the example of sickle-cell anemia. As with many inherited diseases, the occurrence of sickle-cell anemia varies by ethnic group, but it is particularly common in those from Africa. The explanation for this was a long time coming, until someone finally figured out that what we regard as a disease is sometimes an adaptation, a result of natural selection. Sickle-cell anemia confers resistance to malaria, which is to say, if one lives in an area infested with malaria, it is an advantage, not a disease; it is an aid to living and reproducing and passing on that gene for the condition. The other piece of this puzzle emerged only very recently. In 2001, Dr. Sarah A. Tishkoff, a population geneticist at the University of Maryland, reported the results of analysis of human DNA and of the gene for sickle-cell anemia. The gene variant common in Africa arose roughly eight thousand years ago, and some four thousand years ago in the case of a second version of the gene common among peoples of the Mediterranean, India, and North Africa. This revelation came as something of a shock for people who thought malaria to be a more ancient disease. Its origins coincide nicely with those of agriculture, which scientists say is no accident. The disturbance—clearing tropical forests first in Africa, and later in those other regions—created precisely the sort of conditions in which mosquitoes thrive. Thus, malaria is an agricultural disease.

There are similar and simpler arguments to be made about lactose intolerance, an inherited condition mostly present among ethnic groups without a long agricultural history. People who had no cows, goats, or horses had no milk in their adult diet. Our bodies had to evolve to produce the enzymes to digest it, a trick passed on in genes. Lactose is a sugar, and leads to a range of diet-related intolerances. The same sort of argument emerges with obesity and sugar diabetes, cardiovascular disease, and even alcoholism. All are widespread in hunter-gatherer groups suddenly switched to an agricultural diet of dense carbohydrates and sugars. The ability of some people to survive these radical foods evolved only slowly through drastic selection pressure.

All of this points to coevolution, which is the deepest answer to the question of why agriculture. The question implies motive, which is to say we chose agriculture because it was somehow better. There are indeed arguments that it was. Yes, life might have gotten harder in the short term, but storable food provided some measure of long-term security, so there was a bargain of sorts. And while the skeletal remains show a harsh life for the masses, the wealthy were clearly better off and had access to resources, luxury, and security far beyond anything a hunter-gatherer ancestor could imagine. Yet we can raise all the counterarguments and suggest they at least balance the plusses, a contention bolstered by modern experience. That is, we have no clear examples of colonized hunter-gatherers who willingly, peacefully converted to farming. Most went as slaves; most were dragged kicking and screaming, or just plain died.

The coevolution argument provokes a clearer answer to the question: Why agriculture? We are speaking of domestication, a special kind of evolution we also call taming. We tamed the plants and animals so they could serve our ends, a sort of biological slavery, but if coevolution is true, the converse must also be true. The plants and animals tamed us. In biological terms, wheat is successful; its success is built on the fact that it tamed humans. Wheat altered us, altered our genome, to use us.

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This is an excerpt from Against the Grain by Richard Manning