The Elements of Evolution – Agriculture


With the transition to an agricultural lifestyle (from a dependence on many species to dependence on a few), life expectancies tended to decrease rather than increase. The new agricultural diets were coupled with social hierarchies and haves and have-nots, so that even when there was enough food, not everyone received it. ~ Rob Dunn

For their first few million years hominids gathered food and scavenged. Within a few hundred thousand years ago they also hunted small game. Coordinated hunts raised the take to large game.

Herding animals preceded growing crops. Animal husbandry was accepted by beefy ungulates tolerant of human proximity and inclined to an easy life. Poultry took to domestication for nothing more than chicken feed. Experiments in plant cultivation began in the Levant over 23 TYA.

Much of North America, northern Europe, and Asia was covered by ice sheets 20 TYA. By 15 TYA they had receded, bringing warmer and wetter conditions. The sea rose as ice melted. People began to repopulate previously inhospitable places.

In Western Europe the herds of reindeer and other ungulates that had supported many hunting bands moved north as glaciation relented. Some tribes followed them, while others worked out different subsistence strategies by stressing local plants, smaller game, and fish.

Certain tribes in North America stay focused on the vast bison herds. Generally, worldwide, humans opportunistically had a diversified diet: small game, seafood, a variety of fruits, vegetables, and wild cereals, as available. Changes in diet begat technological innovation in implements to harvest plants, trap waterfowl, as well as refinements in preparing and cooking food.

People had never left the Fertile Crescent, which runs from the upper Nile River in Egypt through the Middle East to the Persian Gulf, including the regions of Mesopotamia and the Levant. People settled in villages there well before agriculture took hold, living off local flora and fauna.

The Younger Dryas stadial that began ~12.8 TYA was an abrupt climatic reversal in North Africa and the Fertile Crescent. The forests and woodlands that had reclaimed some of the land dwindled. Small stands of wild grasses and other seed foods became a valuable food source. Early agriculture was a survival strategy against bitter elements which would eventually relent. Drier weather drove people to better-watered locations.

Human societies did not set out to invent agriculture and produce permanent settlements. Instead a series of marginal changes were made gradually in existing ways of obtaining food as a result of particular local circumstances. The cumulative effect of the various alterations acted like a ratchet. Changes in subsistence methods often allowed a larger population to be supported, but this made it difficult, and eventually impossible, to return to a gathering and hunting way of life because the extra people could not then be fed. ~ Clive Ponting

Even before grain crops were grown flattened breads were made from a variety of starchy sources, including the roots of cattails and ferns, which were pounded into flour and baked.

Before the stadial ended, Fertile Crescent dwellers were cultivating figs, grains, and legumes. Plant domestication began with selection: undesirable seeds by their look or taste were discarded.

One advantage of the Fertile Crescent is that it lies within a Mediterranean climate zone: mild, wet winters and long, hot, dry summers. Plants there adapted to survive the long dry season and grow rapidly when the rains return. The lifestyles of many Fertile Crescent plants, especially cereals and pulses, made them useful to humans: annuals which produce large energy-packed seeds.

A 2nd advantage of the Fertile Crescent was that the wild ancestors of many later crops were already abundant and highly productive: occurring in large stands easily harvested.

A 3rd advantage was that these plants were self-pollinating (hermaphrodites) or were easily propagated vegetatively. Such plant reproductive strategies made these florae especially easy for humans to cultivate. The early crops grown in the Fertile Crescent were all hermaphrodites.

A 4th advantage of the Fertile Crescent was it had a wide range of altitudes, microclimates, and microbiomes. This meant staggered harvest seasons and a diversity in both plants and animals.

Crop cultivation was a response to overexploitation of local resources by a growing population. The Fertile Crescent had few large rivers and only a short coastline, providing meager aquatic food resources. Huge herds of one of the most important animals hunted for meat – the gazelle – were slaughtered down to small numbers.

The first domesticated plants in the Fertile Crescent – the so-called Neolithic founder crops – were flax, 3 cereals (barley, emmer, and einkorn wheat), and 4 pulses (lentil, bitter vetch, pea, and chickpea). The choice of grains to cultivate owed somewhat to climate change. Carbon dioxide levels were high following the Younger Dryas, as large deposits of CO2 were released from the oceans when current circulation patterns changed with ice-sheet melting.

All plants grow larger with a higher CO2 but some are more sensitive. Among those are wheat and barley, which grew twice as large and produced double the seeds. That secured their place in the field after the last ice age.

From ~12 TYA, when world population may have been around 2 or 3 million, people began domesticating crops and animals. This occurred independently, at distinct times, in 6 separate locales worldwide. The development of agriculture during this time is termed the Neolithic Revolution.

(Neolithic agriculture after the Younger Dryas was a revival of earlier practice in the Fertile Crescent. Crops were cultivated there at least 23,000 years ago.)

The transition from foraging to farming took place gradually over several millennia. ~ English anthropologist David Harris

Sedentism long proceeded plant and animal domestication, and it was at least 4 millennia after farming began that villages appeared. The appearance of towns was usually the result of wetland abundance.

The general problem with farming – especially plough agriculture – is that it involves so much intensive labor. ~ American anthropologist James Scott

Agriculture furthered settlements. These promoted technological innovations. One of the most important was the development of heavy-duty axes. The ability to fell forests for fields and grazing lands, and work wood, was critical for engendering burgeoning human populations. It also abruptly changed the environment for other animals and plants.

Sophisticated granaries were built early on: circular buildings with internal stone supports for raised floors. This allowed air circulation, thereby reducing the risk of fungal spoilage, and provided some protection from rodents.

Some early cultivation efforts failed. Rye domestication in Anatolia was abandoned. Rye seeds made their way to other parts of Europe as weeds, and were successfully domesticated there, thousands of years after the earliest agricultural attempt.

Plant domestication involves adaptation by plants to living in a human-managed habitat. Some plants resist.

Very long-term natural processes lead to domestication – putting us on a par with the natural world, where we have species like ants that have domesticated fungi. ~ English biologist Robin Allaby

Trade carried both goods and technology; thus began what would become Sumer and other early civilizations.

The first states were fragile. Wars, drought, disease, and the crushing demands of a rising elite made farming a risky, hardscrabble lifestyle. From 1800 to 750 bce settlements in Mesopotamia shrank by over 75%. Warfare-borne disease, deforestation, and salinization of the soil contributed to this decline.

The onset of agriculture did not obviate hunting and foraging as a lifestyle, at least in Europe. 8,500 years ago Europeans were hunter-gathers: not much different in foraging from their ancestors for millions of years. Immigrants from the east brought agricultural knowledge into Europe. Farmers and foragers coexisted for over 2 millennia before agriculture became dominant ~5,000 years ago. Since then, humans have domesticated over 260 different plants, 470 animals, and 100 mushrooms.

Soil & Human Fertility

Until about the last 2 centuries, in every part of the world, nearly everyone lived on the edge of starvation. ~ Clive Ponting

Agriculture was not a panacea for food supply. Instead, it created a boom/bust cycle in population growth.

The initial burst in food supply from cultivation begat a burgeoning population. Ill-founded optimism resulted in food shortages, along with other ills. Domesticated animals brought new diseases: influenza from ducks, measles from cattle, plague from rats.

Woodlands were cut down for building and heating fuel. Deforestation was a habit that men would never kick.

After several years, soil productivity waned. Soil fertility was a mystery to early farmers.

While agriculture developed in the Near East 11 TYA, animal dung was not used for anything other than fuel for fires until 3 TYA. Conversely, while late to farming, some of the earliest European soil tillers caught on to fertilizing their crops with manure 8 TYA. The practice spread.

Early farmers were often less healthy than hunter-gatherers in their heyday, as farming was a hard way to live. Teeth rotted more often. The contrast between nascent farmers and hunter-gatherers may be something of an apples-and-oranges comparison. Hunter-gatherers may have been in better health because the weak were dead.

The advent of settled society swapped high mortality for high morbidity. Relief from the chronic warfare of roving tribes meant grinding out an existence in one spot rather than being ground out of existence altogether.

Crop failure could be catastrophic. Food supplements from the nearby forest were largely lost as residents had deprived the animal life that once lived there of a decent habitat. The critters not killed prudently moved on.

One constant of human history has been a disregard for sustaining natural resources, demonstrating an impressive lack of planning and a sense of entitled self-interest that lessened the quality of life for future generations. From the earliest humans on, casual environmental destruction has been ceaseless in pursuit of immediate gain.

Food shortages shrank human height 15 cm in the early centuries of agriculture. Populations plummeted 30–60%. This was as bad as the Black Death: the bacterial epidemic that devastated Europe 1348–1350, carried by gerbils from central Asia where it spawned.

Land left fallow for a few years regained its vigor for crops. Those that lived through the tough times were more cautious – but then optimism would regain its hold and the cycle would begin again.

Despite severe initial setbacks, a dramatic rise in human population numbers occurred during the Neolithic.


Food storage in Neolithic communities played no small part in dietary choice, especially with variable climate. Seed crops kept well, whereas tubers do not. That difference had knock-on effects.

Animal Domestication

Ancient foragers suffered less from infectious diseases. Most of the infectious diseases that have plagued agricultural and industrial societies originated in domesticated animals and were transferred to humans. ~ Israeli historian Yuval Noah Harari

Animal domestication was often a form of food storage. Those animals indifferent to human presence and induced into appreciating edible scraps were the first to become livestock. Pigs and poultry overcame their hesitations early on.

8,500 years ago, itinerant farmers from the Near East encountered hunter-gathers as they came into Europe. The immigrants brought pigs with them which they had domesticated in their native lands nearly 1,500 years earlier. Europeans so got the taste for pork that they domesticated the wild boar that roamed the continent even before they took to tilling the soil.

Most animals domesticated for food, such as pigs and chickens, are behaviorally and cognitively quite similar to their ancestors and wild counterparts, as they are mainly selected on physical characteristics. This stands in contrast to the case of dogs and wolves, who, of course, share a number of characteristics with each other but, because dogs were selected as companions, are also distinctly different on several cognitive and behavioral dimensions. ~ American zoologist Lori Marino

Dogs and horses can offer close companionship to humans only because they are submissively solicitous. This aspect of canine behavior is well-known but is also true of horses. When a horse needs help it solicits a human using visual and tactile signals. How a horse tries to communicate depends on what the horse thinks the human knows.

 The Descent of Dogs

The earliest dogs arose alongside hunter-gathers. ~ American evolutionary biologist Adam Freedman et al

Wolves and humans are both collaborative social animals: dependent upon cooperation as well as wiles for survival. ~40,000 years ago the two met on the trail of the large grazing animals upon which both preyed and decided they had coinciding interests.

Humans may well have picked up hunting stratagems from watching wolf packs at work. Providing leftovers was another aspect of early interaction. Indeed, scavenging scraps was key to wolves turning into dogs.

A crucial early step in the descent of dogs came in diet. Early dogs managed to thrive on more starch than wolves can stomach. Wolves are hard-core carnivores.

Where dogs descended is still disputed, but Eurasia looks most likely based upon genetic analyses. Dog domestication happened at least twice. Pigs were also domesticated twice: in China and Anatolia.

Companionship and guarding the home front were not the only benefit to humans in adopting would-be tail-waggers. Upon occasion, dogs were also dinner. Whereas westerners have shunned supping on the pooch for centuries, this culinary custom is maintained in the Far East.

The dog is literally the wolf that stayed. The descent of dogs started with a self-selection process: certain wolves especially inclined to tolerate proximity to humans. In effect, dogs invented themselves. Wolves are hard to tame, even as puppies.

Morphological changes from the larger wolf to domestic dog came from minor epigenetic alterations. This is the least momentous change.

Certainly, dogs developed a different lifestyle. Wolves mate for life, and wolf fathers help rear their pups. In contrast, male dogs are promiscuous and pay their offspring no mind.

Behavioral changes are especially striking. Wolves tend to reconcile shortly after conflicts, but dogs do not. Wolves live in packs, so quick resolution to conflicts is critical to group coherence. In becoming domesticated dogs lost many of their pack survival skills. (Wolf conflicts are short-lived, and combatants make up immediately. Contrastingly, dogs tend to fight more viciously and avoid one another after fighting rather than reconciling.)

Wolves will cooperate with men but take the lead in doing so. Dogs wait and see what its human partner does and follow that behavior.

Wolves are ready problem solvers. Dogs hardly give it a go, looking instead to their bipedal companion.

Dogs look to humans when confronted with an unsolvable task. ~ American zoologist Monique Udell

Therein lies the key to dogs’ success in domestication: emotional attachment and understanding coupled to willing submission. Wolves have social-learning skills. The sine qua non of domestication came with dogs taking that to the next level. Dog domestication came through transference of primary social affinity: from packmates to caretakers.

Dogs understand the emotional expressions on the faces of humans. They monitor their master’s attentions.

Dogs key their appeasement behaviors to pacify signs of threat and to garner loyalty. Thus, dogs develop a close empathic relationship between themselves and their human companions. Dogs dislike people who are mean to their caretaker.

Dogs make social and emotional evaluations of people regardless of their direct interest. ~ Japanese zoologist Kazuo Fujita


While most animals were first domesticated for food, the larvae of silk moths were prized for their industry. Over 7,500 years ago the Chinese bred silk moths for larvae that produced more silk and could tolerate extreme overcrowding and human handling.

For over 2,000 years the Chinese kept their silk-making methods secret. Smuggling silkworms out of the country was punishable by death.


The shift from glacial to interglacial conditions dramatically changed the landscape. New plant and animal communities came into being. Vibrant ecosystems arose from previously barren lands.

In the Levant 12 TYA wild cereals grew abundantly on the previously scrappy steppe. Foragers could collect grains in great numbers.

Domestication became a matter of will. Wheat and other crops were grown 10 TYA in various Fertile Crescent settlements.

9,500 years ago Fertile Crescent farms attracted wildcats from the desert: drawn to the rodents that invaded grain stores. These cats domesticated themselves. The friendly ones took advantage of table scraps and protection. They shrank a bit in size and shed some of their fears and antisocial tendencies, allowing them to lounge in comfort around animals that once filled them with suspicion.

China’s development of agriculture mirrored the western experience. The Chinese were grinding grains for consumption 23 TYA, but intensive crop cultivation did not develop until ~12 TYA.

Cattle domestication in both China and the Near East began 10 TYA. Sheep were tamed in southwest Asia around this time. They were kept penned when farmers wanted exclusive use of crop fields.

By 7 TYA the Neolithic populace in China had domesticated rice, millet, soy, swine, chickens, and water buffalo.

In the more than 100,000 years of human existence prior to the Neolithic, there had been times conducive to crop cultivation. What changed most was a higher gear of sociality, resulting in greater complexity in social organization. This was initially driven by a climate not conducive to crops, and thus the dire need to improve food production productivity or perish.

The earliest communities founded on different tribes coming into contact, sparking settlement in the prospect of trade as a path to prosperity. Culture intensified and formalized food production, creating agrarian societies.

Cultural Crops

The specific crops cultivated during the Neolithic shaped sense of community. Wheat was common in the Near East and north China.

In southeast Asia, south China, and Japan rice became the predominant grain. Rice was domesticated in China ~9,000 years ago.

Before mechanization, growing rice took twice as many hours as wheat. To deploy labor efficiently, especially at times of planting and harvesting, rice-growing societies developed cooperative labor exchanges. Neighbors staggered their farms’ schedules to assist each other during these crucial periods.

A collective outlook took root in rice-growing cultures. That sense of cooperative interdependence lingers to the present day, with the Japanese, Vietnamese, and Korean people as exemplary.

Cultures which relied upon wheat and other crops which could be independently grown led to a sense of individualism. This is most apparent in the Fertile Crescent, which birthed a variety of flinty peoples.

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Plants and animals were not the only organisms domesticated. Our love of leavened breads and fermented beverages led to favoring certain yeast. As the same yeast – Saccharomyces cerevisiae – is employed, it makes one wonder who did the domesticating.

We automatically think of domestication as something we do to other species, but it makes just as much sense to think of it as something done to us, a clever evolutionary strategy by other organisms for advancing their own interests. ~ American journalist Michael Pollan


Around 5800 BCE arose the first known farming communities: in the rich alluvial soil of Mesopotamia. Villages dotted the banks of the Euphrates river.

(Other parts of the world, notably China, were likely to have had contemporaneous agricultural communities. The attribution of Mesopotamia as first owes to archeological discovery and its lack thereof at disparate locales.)

By 5500 BCE farmers had started diverting floodwaters from the Euphrates and Tigris rivers onto their fields, then draining them to prevent salt buildup in the soil. Some irrigation canals extended 5 kilometers from the river.

The largest cluster of villages covered 11 hectares: home to 2,500–4,000 people. Villages were linked by kin ties which facilitated leadership and cooperative coordination: essential skills needed to survive a harsh environment.