The Evolution of Animal Agriculture

Gordon King, Department of Animal and Poultry Science, University of Guelph

"Edible, adj. good to eat and wholesome to digest, as a worm to a toad, a toad to a snake, a snake to a pig, a pig to a man and a man to a worm." [Bierce, A. The Devils Dictionary.]

food chain Every living organism is part of a food chain so humans share a necessity to compete directly for nutrients with all other species that are present in the ecosystem. Plants obtain all their essential requirements for maintenance and function by using solar energy to transform simple chemical elements into complex molecules. Animals cannot convert solar energy so must obtain essential nutrients from other sources.

Comparison of Survival Strategies for Plants and Animals

Plants are converters of solar energy, requiring only sunlight, moisture and simple elements to manufacture and maintain their tissues.

Plant success or failure depends entirely on conditions in the surrounding environment.
Under favorable conditions they produce luxuriant growth, reproduce prolifically and perhaps compete with others.
Unfavorable conditions result in slow or no growth. Some, many or all may wither and die, depending on the severity of the unfavorable conditions.
Plants are not total pacifist just waiting to be abused through displacement by other vegetation or consumption by animals. They bend, thrust and spread to gain advantages over other plants. Some develop sharp leaf edges and thorns while others synthesize unpalatable and even toxic chemicals to discourage consumption by animals.

In contrast to plants, animals must obtain nutrients for maintenance of existing or synthesis of new tissues and any production activities by consuming the already formed material of plants or other animals.

Herbivores are the primary consumers, obtaining all nutrients from plants. Some herbivores may be killed and eaten by secondary consumers who, in turn, could provide meals for higher order consumers.
Most species of animals are at the mercy of their environment since they must obtain essential nutrients from their surroundings. However, many can migrate if local conditions become unfavorable and alternatives are accessible.
Humans, in contrast to most other animals, have the mental capacity and manual dexterity to modify environments. They exploit plants, animals and the physical world to satisfy their basic requirements plus many additional desires.

The chemical compounds forming animal flesh are concentrated, easily digested and capable of satisfying all human nutrient requirements. Thus, the earliest Homo sapiens were carnivorous through necessity or choice since, as long as game was abundant, satisfying dietary needs through hunting other animals required considerably less time and effort than by gathering plants. Jack Cohen asserts that a taste for animal flesh was a prerequisite for the development of intelligence since: "You don 't need much intelligence to sneak up on a blade of grass." [Cohen, J. 1991. Biologist 38:7-10].

Agricultural Evolution

Eventually, Neolithic tribes took the first steps towards agriculture, discovering that some plants could be grown from seeds and some animals tamed. This realization that keeping animals and cultivating plants close to the campsite could alleviate the uncertainty of the hunting chase or foraging expedition, provided the first major step in modifying human culture. During the transition from hunter-gatherer to farmer, attention focused on a small number of species and these became adapted into a symbiotic relationship with people. Selected animals were domesticated to provide commodities for consumption by the family group, with surpluses available occasionally for barter or sale to others. In return, humans undertook responsibilities for provision of some feed and care for their livestock, including protection from predators and other potentially distressing factors.

These initial farming efforts, although primitive by current standards, freed humans from total dependence on following wild game and allowed establishment of permanent settlements. Once more effective farming practices evolved, some individuals could pursue other activities for at least part of their time. Such alternative occupations eventually fostered the gradual transition from primitive to more civilized societies. The history of Homo sapiens as food producers rather than as food procure is relatively recent. Once established, however, agriculture reduced the danger of transient or prolonged food shortages and allowed time for other activities. Animal-Human interactions progressed through a series of antagonistic to commensal to exploitative stages.

Antagonistic Interactions

Commensal Stage of Animal-Human Interactions

The earliest agriculturists kept some semi-domesticated animals to assist in hunting, as pack animals or as a mobile feed reserve.

Animals maintain a loose association with humans with humans placing few or no restrictions on animals.
Those animals in association with humans assist in the hunt and warn of potential enemy approach.
In return, animals receive some share of kills and possibly warmth near the fire.
This casual association evolved to situations where humans place some minor restrictions on animals' freedom but provide modest protection from weather extremes and attack by predators.
Humans realized that animals provide a readily accessible food reserve for use whenever game or crops fail and that some species posses potential for draft power.

Exploitative Stage of Animal-Human Interactions

Sometime later, actual keeping of livestock specifically as a food source began in tropical or semitropical regions of the Middle East. The early farmers also discovered that whenever water was available, crops could be produced during most of the year. Thereafter, domesticated animals became an invaluable resource with smaller ruminants, pigs and poultry kept for food production and large ruminants providing the power to operate irrigation systems, plows and other farm implements. Additional innovations from antiquity were exploitation of the milk let down reflex and selection of individuals for prolonged lactation, allowing development of dairying. Also, the discovery of methods for incubating birds' eggs without nesting hens led to increased availability of poultry products. The Romans recognized and adopted improved farming methods such as irrigation systems and oxen drawn plows encountered in conquered regions. These techniques were subsequently introduced throughout western Europe, along with the Roman-devised crop rotation and fallow systems.

Livestock transport Before 1750 a very substantial proportion of the world's population lived in rural areas and engaged in subsistence farming activities. Food supply was never excessive, famines occurred with some regularity, and surpluses were rare, even in the most affluent regions. Such subsistence or near subsistence agriculture still persists in many regions of the world.
Shortages of food provided the major incentive for emigration to newly discovered lands and reduced population pressure in some western European countries. The colonists brought their own livestock with them, introducing new species or strains from Europe into America, Australia, Africa and New Zealand. This was not entirely a one-way exchange. Turkeys, corn (Zea maize), potatoes and tobacco, species previously exploited only by agriculturists in the Americas, were transported back to Europe and eventually spread around the world. An extensive plantation and ranch based agriculture developed in the colonies with a substantial proportion of colonial economy dependent on sending grain and meat back to the mother countries.

Through modern technology, food self-sufficiency or even surpluses resulted in some regions that were traditional importers. Europe no longer needs or wants cereals, meats or dairy products from former colonies and now competes with them to dispose of its own excess production. This creates many problems including depressed producer incomes, excessive export subsidies and the need to develop new trading partners by many countries previously supplying food for EEC members.

The industrial revolution created a wave of urban migration through demand for more factory workers but also increased productivity of laborers remaining on farms. The first innovations of agricultural importance (1750-1880) produced some mechanized equipment for use on larger farms. Of even greater significance was mass manufacture of improved metal hand implements, making these available at reasonable cost so even peasant farmers could benefit. In addition, Pasteur's discoveries on preservation or processing were applied to various foods. Also, the development of clipper and later steam ships provided faster maritime shipment for cereals and other durable commodities from the colonies.

Although the practice of tilling the soil, growing of crops and rearing of livestock was common throughout parts of Asia, Europe, Africa and even in the Americas for millennia, it has a much shorter history in some other regions. Settlers began moving into southern Ontario, clear cutting the forests, establishing farms and displacing the indigenous peoples less than two hundred years ago. The following note provides a brief insight into conditions around Guelph at the beginning of the 20^th century.

"But seventy years or more have wrought very great changes, both on the appearance of the county and its inhabitants, for it was in the year 1832 and the few following seasons that a great many immigrants arrived and settled in Guelph and the surrounding townships."
"In a few years some of the more thrifty of the settlers possessed a yolk of oxen and a sled, also a cow or two, and a few hogs, that fed mostly on beechnuts. These, with a quantity of fowls, kept the larder supplied with such varieties as beechnut fed pork, eggs, and very leaky milk and butter, maple sugar and molasses. Money was very scarce, and when we could sell eggs at three pence per dozen we thought it a good price. But these days and the pioneers have all passed from the changing scenes of the world, having served their day and generation. But to them and their successors, all honor and credit is due, for having changed a dense forest into a fruitful garden, and the haunts of the wolf and the bear into homes of peace and plenty, occupies by a refined, intelligent and educated people, both in city and country, who are also in the enjoyment of many of the improvements of an advanced civilization."
David Kennedy Sr. (1903) Pioneer Days at Guelph and the County of Bruce. Reprinted by the Bruce County Historical Society. 1973.

A more recent phase in agricultural evolution (1880-1950) produced further farm mechanization, employed cold storage for long distance transport of meat or processed dairy products and began the application of genetic selection for livestock improvement. Simultaneously, the emerging science of agricultural chemistry began contributing substantially to improvements in animal nutrition. Since 1950, a better understanding of animal physiology and environmental requirements, the selection of superior genotypes and the availability of pharmaceuticals at reasonable costs resulted in the evolution of production systems yielding very high biological efficiency. Research programs in the areas of animal production and disease provided the background knowledge necessary for development of efficient production practices that provide consumers with animal products at reasonable prices. An almost limitless parade of technical innovations diverted more and more resources for use by humans, increasing their chances for survival and expansion, often at the expense of other species. One consequence of this progression is that domesticated animals became more and more dependent on people. Humans now exercise almost total control over livestock activities and should assume full responsibility for welfare.

Some Major Highlights in the Evolution of Animal Production
Long, long Ago	Small numbers of hunter-gatherers
circa 8,000 BCE	Earliest domestication of animals and cultivation of plants. Beginnings of mixed farming.
circa 2,000 to 2,000 BCE	River civilizations (Sumar on Tigris-Euphrates; Egyptian on Nile; Indian on Indus; Chinese on Yellow Rivers. Mixed farming with small ruminants, pigs and poultry for meat and large ruminants mainly for work.
circa 1,000 BCE	Central and South American Indians had mixed farming with turkeys, cameloids, guinea pigs, corn, potatoes and tobacco.
1^st century	Romans spread innovations such as the iron share plow, different breeds of livestock and the fallow system throughout their empire.
5^th - 15^th centuries	Dark Ages and Medieval Period
16^th century	Colonization begins and European livestock breeds transported to "New World."
17^th century	Formation of scientific societies and breed associations. Europe imports considerable food from colonies.
18^th century	Industrial revolution promotes agricultural research, production and storage of forages, establishment of herd books and veterinary collages.
19th century	Louis Pasteur: agricultural microbiology, chemistry and animal nutrition established as disciplines in agricultural colleges.
Early 20^th century	Discipline approach to research and practical application of results. Agricultural mechanization, refrigeration, Mendal rediscovered.
Mid 20^thcentury	Antibiotics, AI, sire evaluation, more mechanization, move to monoculture, total confinements, European 'exotic breeds' to N America.
Late 20^th century	Biotechnology rediscovered, recombinant DNA products, genetic engineering, interest in sustainable production.
21^st century	More emphasis on recycling (less on specialization?). Food surpluses in some regions should lead to reduces government subsidies for surplus generating production. More society concerns about animal welfare, environmental quality and sustainability. Higher energy costs + questions about consumer preferences=uncertainty!