Hiatus Post — Domestication

The institute will be on hiatus for this week but we’ll return next week with a fresh batch of posts and podcast, all focused on the topic of meat. Until then, please enjoy excerpts from the recently published book Why Did Ancient Civilizations Fail? (available for purchase on Routledge and Amazon).

Domestication is the artificial selection of beneficial traits in a plant or animal that, over time, fundamentally changes that species, especially food species. In the wild, environmental factors favor the fittest members of each species. Humans circumvent that selection process and choose the most desirable individuals. For example, wild grains differ from domesticates in a few key ways. First, wild seeds are meant to fall off of the stalk because that is how they are spread by the plant. Second, wild seeds are no larger than they need to be to sustain germination. Third, wild plants produce enough seeds to repopulate their surroundings. Humans have changed these traits in domesticated grains. If seeds simply fell of the stalk, they would be difficult to collect. Larger seeds contain more nutrients than smaller seeds, and it is more efficient to gather the plants with the most seeds.

The domestication process may have been accidental at first. Take our hypothetical band of hunter-gatherers that goes out to collect wild wheat one afternoon. They might use a knife or sickle-like tool to cut the stalks of wheat, after which they carry sheaves of wheat back to their camp. As they cut, pile, bind, and carry these stalks of wheat, many seeds fall off. Wild wheat has what is called a brittle rachis, which is what connects the seed to the stalk. This rachis breaks to allow seeds to be dispersed.1 Individual organisms vary within every natural population, and wheat plants are no different. A few plants may have robust rachises, and it is these seeds that will survive the trip back to camp. Seeds planted by this group will be drawn from those plants whose seeds had robust rachises. By repeating this process over many years and planting some of those seeds that survived the trip, the future generations of wheat plants will have a reduced seed dispersal mechanism. Over time, the plants came to depend on humans to disperse their seeds, because they no longer fell off the stalk. At this point, one might consider the plant to be domesticated. Humans may have played a more active role in selecting seeds for size and plants for increased numbers of seeds. By winnowing and selecting the largest seeds, our band of hunter-gatherers would have encouraged the growth of large-seeded plants. Also, they may have preferentially gathered those plants with more seeds attached to each stalk, again encouraging a larger amount of nutrients per plant in later populations. This process of slow, gradual change would take place over hundreds or thousands of years and continues even today, although modern agro-science uses a more sophisticated selection and modification process.

The invention of agriculture and domestication was made independently in at least three areas. The Fertile Crescent of the Middle East covers the hills across much of Israel, Syria, Turkey, and Iraq. This region hosted some of the world’s earliest cities such as Jericho and Çatalhöyük before 9600 and 7300 BCE2 respectively. Its agriculture was dominated by wheat, barley, rye, chickpeas, peas, beans, and lentils and emerged between 10,000 and 7000 BCE. At the same time in roughly the same area, goats, sheep, pigs, and cattle were also domesticated. It was this suite of domesticates that spread north and west through southern Europe into Western and Northern Europe over the next 3000 years. Egypt may have had domesticated cattle as early as 7000 BCE, but certainly by 5000 BCE cattle, sheep, goats, pigs, barley, wheat, and flax were commonly husbanded in the Nile Valley. Early domesticates, such as wheat, barley, and cattle, spread to the Indus Valley by 6500 BCE. In a separate process of domestication, around 7000 BCE rice was farmed along the Yangzi River and millet along the Yellow River in China. Mesoamericans first domesticated gourds to use as containers about 7000 BCE but moved on to corn by about 5000 BCE. In South America, potatos and mantioc were cultivated as early as 6500 BCE.

1Alternatively, people collected grains by knocking the grains off of the stalks in the fields, much like the harvest of wild rice in my native state of Minnesota. This leaves only the seeds with the strongest rachises to germinate for the next year. This selection would also create plants with suppressed seed dispersal mechanisms appropriate for agriculture.

2This book uses Before Common Era (BCE) and Common Era (CE) instead of B.C. and A.D. This is a common practice among archaeologists who do not want to use a Christian dating scheme while discussing other cultures. It would be best to use the native calendar of each society, but this would be unnecessarily complicated.

Leave a Reply