The complicated techniques that allow breadfruit to be cultivated are among the many that have been developed by humans since the dawn of agriculture. Propagation is one of the key parts of domestication, because without it you can’t make more of your food source. Doing it consistently requires a tremendous amount of knowledge about the biology of the species in question—life history, preferred growth conditions, and many other details. Most traditional peoples acquire this knowledge through observation and trial and error, ultimately passing it on through word of mouth; modern research is being applied to the same end in the more recent development of aquaculture.
During my conversations in Stavanger with Marine Harvest’s researchers, I heard two words repeated by many different people: “closed cycle.” In farm-speak this refers to the ability to breed animals and plants in captivity so that there is no input from the wild—the breeding cycle is “closed” and you can grow as many of the species in question as you want. This is the real test of a farming operation, and the true meaning of domestication. It is also what much of Marine Harvest’s research-and-development budget is spent on: finding a way to coax species through the various stages of birth, growth, and reproduction. While we take it for granted that ranchers can breed cattle and poultry farmers can raise chickens from eggs to adulthood, it actually required a great deal of effort to figure out how to do it in the first place—as with the propagation of breadfruit.
Perhaps the best-studied example of the development of agriculture during the Neolithic period is described in an epic book about the excavation of a place called Abu Hureyra, in northern Syria. In Village on the Euphrates, Andrew Moore and his coauthors laid out the critical role of propagation early on: “Domestication may be defined in several ways … but the essence of it is that humans usually influence the breeding of the species concerned.” This is the key step in creating more of the species; if your animals and plants don’t produce offspring, you have to keep going back to the wild for more.
Domestication is about far more than simply making more of the species in question, though. It is also about selecting for traits that make that species a better source of food. For instance, wild cod typically mature in four to six years, but Marine Harvest’s scientists have selectively bred fast-maturing individuals who reach adulthood in only two. Shorter time to maturity means more fish in the markets—it makes sense. Domestication is also about modifying the farming environment to make sure the species in question has what it needs to thrive. Halibut, for example, are currently being studied by Marine Harvest scientists to see if they are a viable species for domestication. While they yield delicious flesh that is very popular on European and American dining tables, their unusual biology has forced the scientists to get creative in order to raise them. This is because, although halibut are born looking like normal fish, after about six months one of their eyes literally migrates along the top of the head, so that a few months later both eyes are on the same side. The fish starts to swim on its side and becomes a bottom dweller, preferring to live next to a horizontal surface. This aspect of its life history is problematic for fish farmers, as it severely limits the number of fish that can be raised per unit area—the third dimension in the pen isn’t really being used by the halibut, because they all want to be on the bottom. To get around this problem, Marine Harvest’s scientists have devised “halibut high-rises” composed of columns of mesh shelves that allow more fish to be packed into the same diameter pen. The strategy seems to be working: the fish happily swim out from the high-rise to eat food that falls from the surface, then return to their perches to rest.
FIGURE 10: A “HALIBUT HIGH-RISE.”
Selecting for the traits that allow for domestication is easier in some species than in others, and it turns out that our Big Three—wheat, rice, and corn, which together provide more than half of all calories consumed in the modern world—are particularly suitable for selective breeding. All of them are what is known as polyploid, which means their genomes have been duplicated—the chromosome number literally doubled at some point in the past few million years, in some cases more than once. Many plants are polyploid, and genome duplication seems to have happened quite often during plant evolution. It’s as if you photocopied the entire genome and inserted that spare copy into the nucleus of the cell. This has some pretty interesting consequences for what you can do to the plant with selective breeding.
When you have a spare copy of something, you can take more risks than if you had only one. It’s kind of like the “lives” you have in a video game—you can make poor choices and still keep playing. This holds true at the genetic level as well, since having a duplicate allows you to tinker with one of the copies while retaining an unaltered version. It gives you a backup, in other words, in case something goes wrong in your tinkering. Duplicate copies can open up new opportunities for evolutionary change without risking the loss of vital functions—and can sometimes lead to more rapid evolution. This idea was first championed by Susumu Ohno, a Japanese-American population geneticist, who wrote a classic book entitled Evolution by Gene Duplication in 1970. In this book Ohno presented what he believed to be one of the fundamental mechanisms of molecular evolution: duplicated genes leading to rapid evolutionary change due to the relaxed selection made possible by having a backup copy. He also coined the term “junk DNA,” referring to the large stretches of DNA in the genome with no known function. This is the ultimate fate of gene duplicates that suffer a fatal mutation and become nonfunctional. But the working copy of the gene keeps the organism alive. Almost all cancerous tumors duplicate their DNA, becoming polyploid as they develop. Geneticists believe this duplication of key genes gives them more plasticity—more options to develop in ways that normal cells never would.
In addition to being polyploid, wheat, rice, and corn also appear to have a very high rate of mutation. Their DNA, it seems, is in a constant state of flux, duplicating and deleting parts in a molecular shuffle that produces a high level of natural variation in many traits. Some of this shuffling is caused by the presence of small DNA parasites known as transposable elements. These are like little viruses embedded in the genome, and may be the remnants of what were once active retroviruses (a family that includes HIV, the human immunodeficiency virus) that lost their ability to infect other cells but retained the retrovirus’s penchant for integrating into DNA and hopping around. Their discovery by Barbara McClintock in the 1940s and 1950s, during her efforts to understand some of the odd characteristics of corn genetics, was initially met with skepticism from fellow geneticists, but later research showed her work to have been correct, and she was awarded a Nobel Prize in 1983.
Corn is a wonderful example of how careful selective breeding produced characteristics that are a far cry from those of corn’s likely wild ancestor. Teosinte looks completely different from today’s cultivated corn—as you can see in Figure 11—and while it is impossible to calculate the level of observational research and selective breeding required to domesticate wheat, rice, and corn during Neolithic times, it must have taken an enormous amount of effort to select for such extreme changes. In fact, recent genetic studies have suggested just how difficult it must have been.
Three genes, known as teosinte branched 1 (tb1), pro-lamin box binding factor (pbf), and sugary 1 (su1), are key to creating certain traits that distinguish corn from teosinte. Despite their complicated names and even more complicated biochemical functions (tb1, for example, determines how the cobs are arranged on the corn plant, while su1 determines the mix of sugars found in the corn kernel), all seem to have been under strong selection as early as 4,400 years ago, according to a recent analysis of these genes in ancient corn remains. However, selection for these traits seems to have been ongoing nearly 2,000 years later, showing how difficult the process of selection is, particularly in a society lacking today’s scientific knowledge. That these early Mexican farmers were able to create corn from teosinte is remarkable.
The genetic p
lasticity of wheat, rice, and corn gave them an edge over other potential food crops, and it is a large part of the reason that they are so widely cultivated today. The Natufians at Abu Hureyra consumed around 150 different plants, gathered (along with wheat) from the rich hills of the northern Fertile Crescent, but by the time domestication was complete, a few thousand years later, their diet had dropped to only eight species, and wheat was by far the most important dietary component. Today, the Big Three cereals account for around 90 percent of grain species under cultivation—they won the race to be humanity’s most important foods.
But here is the sting in the tail. When we used our amazing ingenuity to select for traits that allowed us to cultivate these incredibly successful foods, we unknowingly set in motion a strong selective regime on ourselves. In some ways their success has created a sort of nutritional “cancer” that has taken on a life of its own, coming to dominate our diet in ways those first farmers probably never could have imagined. (Michael Pollan’s excellent book The Omnivore’s Dilemma discusses the rise of modern corn agriculture in a chilling overview of industrial farming.) The end result of the higher—and less complex, in terms of species mix—carbohydrate levels in our diet is still playing out, as we’ll see in the next chapter. But first, back to the immediate fallout from agriculture: more people, and what to do with them.
FIGURE 11: TEOSINTE (LEFT) AND CULTIVATED CORN, SHOWING THE PROFOUND DIFFERENCES BETWEEN THE TWO. (PHOTO COURTESY OF JOHN DOEBLEY.)
SOCIAL MALIGNANCY
We now come to the crux of what this book is all about. When our ancestors created agriculture around 10,000 years ago, they had no idea of what other changes they were setting in motion. They were simply responding to an immediate need for more reliable sources of food during a time of climatic stress, obviously making decisions about the future based on the near term rather than how events might ultimately play out. They were unaware of what, by changing their fundamental relationship with nature, they were unleashing on the world. Instead of relying on nature’s plenty, they were creating it for themselves. By doing so they divorced themselves—and us—from millions of years of evolutionary history, charting a new course into the future without a map to guide them through the pitfalls that would appear over the subsequent ten millennia.
The first unintended consequence of this change was that more food produced more people. While the human population had been growing slowly since around 60,000 years ago as we slowly expanded around the world as hunter-gatherers, this was an entirely different form of growth because it was both faster and geographically constrained. Humans had been held back in their population expansion by the ice age, when the challenging climatic conditions made life more difficult. If, as genetic evidence suggests, we started with a population of a few thousand people living in Africa around 70,000 years ago, by the beginning of the Neolithic period our number had grown to only a few million—a thousandfold increase in 60,000 years. With the invention of agriculture, though, the growth rate suddenly jumped to levels never before seen in the evolutionary history of a large primate. The small Natufian villages became towns virtually overnight, and this brought the second consequence of agriculture: the development of governments.
In a typical hunter-gatherer society, most people are of roughly equal social status. Of course there is variation in skill levels—one person may be better at hunting, another better at telling stories that pass on the lore of the culture, another perhaps the best at sewing—but all are recognized as contributing to the society. Disputes are generally settled in one of two ways, either through group adjudication or tribal fission. Fission, however, is impossible when there is limited access to key resources, such as cultivable land or water supplies. It becomes impossible for part of the tribe to simply move to a new place, since the resources won’t necessarily be available elsewhere; in addition, sedentary people have likely invested a large amount of effort in creating their houses and other immobile material goods and will be reluctant to leave them. The need to remain in a particular place led certain rare hunter-gatherer communities, such as the pre-Columbian Native American communities of the northwest coast of North America and the Paleolithic Jomon population of Japan, to create their own complex systems of government. The large population sizes that were reached through the exploitation of incredibly rich fishing grounds, and the necessity of preserving access to these areas, meant that these communities faced similar pressures toward organization as did early agricultural communities. These coastal dwellers are generally recognized as special cases, however, and the vast majority of hunter-gatherers surviving today have—as those in the past likely had—a more egalitarian social structure.
What were these early forms of Neolithic government like? It’s probable that they started out relatively egalitarian, as suggested by archaeological sites such as Çatalhöyük, in present-day Turkey. This Neolithic site dates from around 9,500 years ago, and over the six millennia it was inhabited, it probably fluctuated in population between five thousand and ten thousand people. Clearly a departure from the small Natufian and early Neolithic farming villages, it was the world’s first city, according to its discoverer and excavator, James Mellaart. However, despite its considerable population, the buildings are all roughly comparable in size and appear to have been used as dwellings. The fact that there are no clearly defined temples, or houses that are significantly larger than the others, argues for a fairly even distribution of wealth, according to Ian Hodder of Cambridge University, who is currently the lead archaeologist at the site. Rather, the people of Çatalhöyük seem to have retained many aspects of their egalitarian hunter-gatherer past. But its size—which is thought to have been in large part due to wealth gained through the trade in obsidian, found in large quantities in nearby mountains—meant that such an egalitarian social structure couldn’t last.
The basic economic unit at all early Neolithic sites like Çatalhöyük was the nuclear family. It seems to have been how people apportioned farmland, stored their grain, and even practiced their religion. At Çatalhöyük, for instance, there seems to have been a well-developed ancestor cult in which people would bury the bones of their departed family members in the house, right under the floor. It was a way of clearly staking a claim to the location, and it reflected their sedentary and family-focused culture.
The formalization of religion during the Neolithic period likely proceeded slowly and took shape with the increasing stratification of society. Although we have no way of knowing for sure, it’s likely that these early religions were based on formalizations of beliefs that had existed prior to the development of agriculture. The world’s hunter-gatherers are traditionally animists, and their belief in a multitude of spirits and gods mirrors their reliance on a complex variety of natural resources. Agriculturalists, with their relatively simple food supply and their view of nature as something that needs to be controlled rather than cooperated with, were sociologically predisposed to create religions with fewer, more powerful gods—and gods in their own image at that. The first widespread images of humans appear only in the latter part of the Upper Paleolithic, with the near-universal presence of Venus figures in the archaeological record of Europe at this time. Such figures continued to be important during the Neolithic period, perhaps because humans recognized their increasing power. Their importance may have risen in concert with the development of the so-called goddess cult of the era, “goddess” being the name given to the female figures placed prominently at sites like Çatalhöyük.
These Venus figures, clearly symbolic, with their exaggerated breasts and hips, may have reflected the high social standing of women as givers of life. In a prescientific society, it’s possible that the link between sexual activity and reproduction may not have been understood; if so, the birth of a child must have seemed supernatural. Furthermore, if women were the first to cultivate plants, their prominent role in coaxing life from the soil would have been clearly recognized. All fertility, whether from the l
oins or the land, sprang from them. Does this mean that women had higher social status than men—that is, were these early Neolithic societies matrilineal, with inheritance coming down the female line rather than the male? Perhaps, though some archaeologists (Ian Hodder, in particular) have argued against this interpretation, suggesting that men and women—at least in Çatalhöyük—were of similar status. Clearly, however, this didn’t last.
FIGURE 12: TERRA-COTTA VENUS FIGURINE FROM BULGARIA, CIRCA 5000 B.C. SOURCE: MARIJA GIMBUTAS, THE LIVING GODDESSES, UNIVERSITY OF CALIFORNIA PRESS, 1999.
As humans expanded their population size, they were forced to move from the original centers of domestication, mountain valleys, out onto the plains, since the small land area near easily accessible water supplies could not sustain an unlimited number of people. This necessitated the development of a system for transporting water and irrigating fields. Constructing irrigation canals requires that large groups of people work together toward creating a common, shared piece of real estate. This meant they had to develop some way of administering the work itself, as well as the maintenance of the completed canals and the access to the water—suddenly a scarce resource. And this meant they needed something else that had never existed before in human history: a formal government, with specialized bureaucrats and, most important, authority. Otherwise, why listen to someone telling you what to do?
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