WHEN our Stone Age ancestors first began cultivating their food instead of foraging for it in the wild, they could not have foreseen what a momentous step they were taking. Almost all the trappings of modern life flow from that fateful decision. Farming allowed people to live together in large, permanent settlements. Its regular surpluses gave some the freedom to spend their lives pursuing goals other than food production. And ultimately agriculture let us create the sort of complex stratified society we live in today.
With so much seemingly going for it, archaeologists have long seen the transition to farming as a crucial step in the march of human progress. Once our ancestors realised they could plant seeds in springtime and reap a nourishing harvest a few months later, everyone wanted a slice of the action, and the idea spread quickly. But studies of modern hunter-gatherers suggest that farming may be far more labour-intensive than foraging for food. And skeletal remains of Stone Age farmers show more signs of tooth decay, malnutrition and infectious disease than those of their hunter-gatherer predecessors. It seems that farming may not have been such a slam-dunk improvement after all.
So why were our ancestors so eager to adopt a lifestyle that left them worse off? Some experts think hunter-gatherers may have been forced into farming by overpopulation or climate changes that strained their old food supplies to breaking point. Others contend the rise of agriculture had less to do with filling hungry bellies than with feeding a hunger for status. So far, our window into the past is too small to be sure which explanation is right. But the answers should get clearer in the next few years as researchers gather crucial new data.
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Part of the difficulty in explaining the rise of farming is that it was not a single event. Agriculture had at least seven independent origins around the world, each with its own unique set of conditions. Then there is the fact that the switch did not happen overnight, or even within a few generations. The archaeological record shows that when people first domesticated crop plants they remained a minor part of the diet for centuries or even millennia. Only much later did farmed crops move to centre stage as the main source of food. Any explanation for the rise of farming must consider the driving forces behind these two separate steps.
Initial cultivation began in the eastern Mediterranean region near the end of the last ice age, around 12,000 years ago. At that time floras and faunas were changing rapidly. North American hunter-gatherers would have been especially distressed by the extinction of many of the large game animals that once provided them with relatively easy and nutritious food. “We know for a fact that the ecological circumstances were changing dramatically. The animals weren’t there for them to take any more. It’s at that point that we see people start intensively utilising plants,” says Dolores Piperno of the Smithsonian Institution in Balboa, Panama, and Washington DC.
Such adaptability is certainly a characteristic of modern hunter-gatherer societies. “They’re constantly fiddling with their sources of food to see if there are any ways they can improve predictability or reduce risk,” says Bruce Smith, director of the archaeobiology programme at the Smithsonian Institution in Washington DC. So it is reasonable to assume that as the glaciers receded and the climate became more suitable for cereal grasses, Stone Age foragers would naturally have added them to their diet and learned ways to improve their growth such as selective weeding and burning to clear land. Such semi-domesticated species might then have remained as one option on the menu of people who were still primarily hunter-gatherers for many generations.
Competitive feasting
Many archaeologists, though, are turning away from this scenario in favour of a completely different explanation. The first domesticated crops, they suggest, may have been the Stone Age equivalent of peacock tongues or caviar – in other words, luxury foods intended for feasts. Throwing a feast would allow the giver to assert their status, cement alliances and accumulate favours that they could later cash in for political gain. “It’s an incredibly powerful motor for cultural transformation, and the fuel this motor uses is food,” says Brian Hayden, an archaeologist at Simon Fraser University in Vancouver, Canada. Today’s high-powered socialites will recognise the impulse – and the need for exotic ingredients to impress guests.
Certainly, many of the earliest domesticated plants seem better suited to the role of palate-teasing delicacies than staples, Hayden notes. Lentils, for example, usually grow just two per wild plant and would have been terribly finicky to harvest. A hungry person could have filled his belly quicker with any number of other plants, yet lentils are among the first crops of the near East. In Central America, the earliest crops include chillies, avocados and gourds. “These were things that would have virtually no impact on people’s diets if they were starving,” says Hayden. Indeed, these gourds are completely inedible – but they make fine serving vessels for a feast.
Even crops that we now think of as quintessential staples, such as rice, tend to be used as high-status specialty foods by traditional societies today. In the Torajan culture on the Indonesian island of Sulawesi, for example, poorer families subsist mostly on manioc and other root crops and hoard their precious rice for feasts. Even the rich tend to eat other foods for everyday meals and pull out the rice for company. In the Stone Age, something similar may have happened with grains such as wheat and barley. Many experts think that beer, not bread, was the most important early product of these grains – and the importance of alcohol in a feast is obvious. Animals, too, were probably used for celebrations rather than everyday meals, as they still are in today’s subsistence societies.
If the first crops were prestige items, not staples, that would explain why they remained such a minor part of the diet for so long. And the times and places where crops first appear fit the expectations of Hayden’s “competitive feasting” scenario. “We expect domestication to occur in fairly affluent societies, and where there’s some social and economic complexity and inequality, and I think that’s exactly what we find,” he says. Storable, status-enhancing grains could also have been bartered for other luxury items, such as polished stone axes, the production of which seems to coincide with early grain cultivation in many societies.
The case for farming-as-luxury has not been clinched, though. “I think it’s a good testable hypothesis, but the jury is still out,” says Deborah Pearsall, a palaeoethnobotanist at the University of Missouri in Columbia. Archaeologists need to look more closely at evidence from around the world of societies as they cross the threshold into agriculture to see whether they were complex enough to support competitive feasting and other ostentatious displays. So far, it is mixed. Some societies, such as those in the near East and northern Europe, appear to fit. Others, including ones in the Americas and New Guinea, were much simpler at the dawn of agriculture, says Piperno.
And what of the second step in the agricultural transition? Why did domestic crops finally push aside foraged food and become the mainstay of our diet? Here the story is even more tentative. “It’s an interplay of a lot of different variables over time, and it’s hard to tease out any prime mover,” says Smith.
One idea is that advances in technology allowed more people to indulge their desire for prestige foods. It became possible for more and more people to eat these food as farmers learned to coax bigger yields out of their grains and as the grains improved through generations of selection. Bigger stores of grain would also have given their owners more wealth for purchasing other luxury items and so increased social inequalities. The emerging elites would have a strong incentive to squeeze more production out of the under-classes, leaving them less time for foraging, and forcing them also to rely more on cultivated crops.
Another explanation is that once people began settling into semi-sedentary farming lives, a population trap would have been sprung. “Farmers have a lot more kids than hunter-gatherers do,” says Piperno. “In evolutionary terms, it’s a more successful strategy. Those foragers that didn’t become farmers were simply outcompeted and replaced in many regions of the world.” And as growing populations filled in the landscape, the remaining hunter-gatherers would have found it harder and harder to forage for food without treading on the toes of other groups. They may have had little choice but to work harder at growing the food they needed. Such a move would have left them increasingly vulnerable to crop failure and famine, but by then there would have been no going back.
So far, archaeologists have little evidence to help them assess the relative importance of these two broad explanations for the rise of agriculture. But some answers may be written in the bones of ancient people. If overcrowding and food shortages drove our ancestors to farming, then their skeletons should show signs of malnutrition before agriculture took off. If people switched to farming in pursuit of power and prestige, on the other hand, any decline in health should come well after farming becomes established, as a result of diseases associated with keeping livestock and storing grain, and from malnutrition caused by poor diets or following bad harvests.
So far, the skeletal record is not up to the task of making that distinction. However, a team of researchers aims to fix that by compiling an extensive database of ancient skeletons from around the world to track signs of disease, malnutrition and injury throughout prehistory and historical times. Eventually, the team hopes to have assessed 75,000 skeletons from Europe alone, and perhaps 200,000 worldwide. “Hopefully one could then recover skeletons that are on the cusp – before, during and after the transition,” says Richard Steckel, an economist and anthropologist at Ohio State University in Columbus and one of the project leaders.
As the bones tell their stories, anthropologists should be able to pinpoint exactly when and under what circumstances health problems began to emerge. And that may eventually tell researchers whether agriculture – one of humanity’s biggest inventions – arose as a clever innovation to bolster social status, or as a necessity by which growing numbers of hungry people could make the best of a bad deal.