Agriculture 1000
Pages 73-104
Jason Daffy, Michael Day, Adam Diakow, Colin
Doenz, and Evan Durnin
The focus of this piece is the spread of domestication. A domesticated animal is
defined as an animal selectively bred in captivity and thereby modified from its wild
ancestors for use by humans who control the animal’s breeding and food supply.
Domestication involves wild animals’ being transformed into something more
useful to humans. Truly domesticated animals differ in various ways from their wild
ancestors. Those differences result from two processes:
1. Human selection of those individual animals are more useful to humans
than other individuals of the same species.
2. Automatic evolutionary responses of animals to the altered forces of
natural selection operating in human environments are compared with
wild environments.
Domesticated animals have diverged from their wild ancestors in the following
ways:
1. Many species have changed in size: cows, pigs, and sheep become smaller
under domestication and guinea pigs became larger.
2. Some species of domestic animals have smaller brains and less developed
sense organs than their wild ancestors, this is because they don’t need the
bigger brains and more developed sense organs on which their ancestors
depended to escape from wild predators.
An example of changes developed under domestication is the wolf. The wolf is a wild
ancestor of domestic dogs.
Most of these domestic mammals were found in many parts of Eurasia while
small amounts were found across the rest of the continents. This unequal distribution
became an important reason why Eurasians were the ones to end up with guns, germs and
steel. This also has to due with the fact that Eurasia contains the worlds’ largest
landmass and it’s diverse ecologically. Eurasia was the continent with the most candidate
species of wild mammals to start out with, and lost the fewest candidates to extinction in
the last 40, 000 years. This is compared to the continents Africa, The Americas, and
Australia.
Potentially domestic animals must satisfy six major criteria, the failure of any one
will prevent domestication. They are:
1. Diet
2. Growth rate
3. Problems of captive breeding
4. Disposition
5. Tendency to panic
6. Social structure
Diet is based on feed conversion. Selection of herbivores will provide better feed
conversion. Growth rate relies on feedlots to improve average daily gain.
Social structure involves living in herds, well developed dominance hierarchies,
and the herds occupied overlapping home ranges rather than mutually exclusive
territories. These attributes allow humans to take over the dominance hierarchy and helps
to confine them due to their herding tendencies in the wild.
Animals failing to breed under captive situations are one problem of captive
breeding. Animals with particularly mean or unpredictable dispositions can not be
trusted. Animals that panic will either injure or be injured easily when handled. Only a
small percentage of wild animal species meet all of the above criteria.
If you look at a map of the world you will notice that the Americas span a much
greater distance north to south than east to west. In Eurasia the major axis is from east to
west. These axis orientations affected the rate of spread of crops, livestock, and possibly
writing, wheels and other inventions. This geographic feature is responsible for the very
different experiences hat Native Americans, Africans, and Eurasians have had in the last
500 years.
Food production arose independently from between 5 and 9 areas around the
world. Yet already in prehistoric times food production had started in many other areas
as a result of the spread of crops, Livestock and knowledge of how to grow them and, in
some cases, as a result of migrating farmers and herders.
The main spread of food production were from southwest Asia to Europe, Egypt
and North Africa, Ethiopia, Central Asia and the Indus valley: from the Sahel and west
Africa to east and south Africa, from china to southeast Asia, the Philippines, Indonesia,
Korea and Japan; and form Mesoamerica to north America. Even in areas where food
production originated there was an addition of crops and livestock and techniques from
other areas of origin. As food production spread around the world some areas proved to
be much more suitable than others. Among all the areas where food production spread
during the prehistoric era the rates and dates of spread varied considerably. The rate of
spread from east to west like form southwest Asia both to Europe, Egypt and the Indus
valley was very fast at 0.7 miles per year. The rate of spread from north to south like
from Mexico to the U.S southwest was less than 0.3 miles per year.
There were also great differences with which species of crops and livestock
spread. Sometimes a certain species would spread but another species would not, even
though they would both be valuable. An expression of this geographically different
spread of food production is the phenomenon termed preemptive domestication.
Most of the species that spread vary genetically from area to area due to
mutations. Similarly the changes required to change wild plants to crops are due to
alternative new mutation or new courses of selection to yield equivalent results. If
someone carries out a genetic analysis for major new world crops many of them prove to
include two or more of these alternative mutations. This suggests that the crop was
domesticated independently in at least two different areas, in at least two different areas
and those different varieties of crops inherited different mutations from different areas.
In Mesoamerica and South America plants were domesticated independently at least
twice. This implies that for just a single domestication the plant spread more quickly
than 2 or more domestications.
The Fertile Crescent showed a very rapid spread of crops. This is partly because
localities distributed east and west of each other at the same latitude share exactly the
same day length and seasonal variations. They also tend to share the same diseases,
temperature, rainfalls and habitats. An example is Portugal, Japan, north Iran lie about
4000 miles east or west of each other but on the same latitude and have similar climates.
This leads to plants in specific areas to germinate, grow and have different disease
resistant. Seasonal changes, day length, temperature, and rainfall affect how the plant
will grow from seed to maturity. Each plant population becomes genetically adapted
through natural selection to respond to its own climate. An example is months with
temperature and day length suitable for plant growth are shortest at higher latitudes and
longest at the equator, which affects the growing season.
Animals like plants are adapted to latitude related climates. Much like us humans
who have adapted to certain climates. Example tropical people developed some genetic
resistance to malaria where as Europeans used to die in droves from it. This was part of
the reason why the Fertile Crescent domesticates spread west and east so rapidly. An
example when farming came to Europe from Hungary around 5400 B.C it spread so fast
that archeologists have trouble deciding where farming originated in Europe.
By the time of Christ cereals of the Fertile Crescent were growing from Ireland to
Japan a distance of 8000 miles. This allowed the launch of agriculture over this area.
Due to this the Roman Empire used to import or use crops from the fertile crescent much
like a modern day restaurant imports food from crops grown all over the world or that
originated from different parts of the world.
Eurasia was the world’s widest band of land at the same latitude and therefore the
most dramatic example of rapid spread domesticates. Another example of rapid spread is
the subtropical package of south china that includes bananas, taro, yams, chickens, pigs,
and dogs spread 5000 miles with in1600 years.
The east-west diffusion in Eurasia was fairly easy compared to the spread of
agriculture in Africa. The Fertile Crescent crops/animals didn’t reach South Africa due
to tropical conditions that halted there spread thanks to disease and extreme climate
change. This stopped the advance of cattle, sheep and goats for 2000 years until humans
were able to develop new livestock breeds around 1-200 AD . This was 8000 years after
livestock was domesticated that they finally reached South Africa.
Likewise since Fertile Crescent crops couldn’t reach South Africa. They were
forced to domesticate there own plants which were successful in there own climate but
were not able to be moved north into different climates much like the Fertile Crescent
crops halt. It was not until Europeans brought Fertile Crescent crops in 1650 to South
Africa that agriculture began to thrive. This came with a price of constant war between
Europeans and blacks and many new diseases.
Much like in Africa the Americas had the same problem with agriculture moving
south. Although some crops and animals did make it to South America in the preColumbian era.
Difficulties in Spreading Agriculture
There were many factors that held the spread of agriculture back in both the Americas
and Africa. The main theory behind this is the North-South axes in which the Americas and
Africa seem to diffuse their ideas and products of agriculture very slowly from one end of the
spectrum to the other. In some cases it took plants 200 years to cross an area of only 1200
miles. For example some of the plants and animals that were in the cool highlands of the South
American Andes would have prospered greatly in the very similar climate of Mexico.
However any northward spread of this was stopped completely by the hot intervening lowlands
of Central America.
In North America, corn that was domesticated in Mexico failed to grow in eastern
northern parts of America, because of the shorter growing season and cooler
temperatures. Not until 900 A.D. did corn begin to be developed in America.
Most fertile crescent crops prove, upon genetic study, to derive from only a single
domestication process, whose resulting crop spread so quickly that it preempted any other
incipient domestications of the same or related species.
Topographical & Ecological Barriers
Topographic and ecological barriers, much more pronounced on some continents
than on others, were locally important obstacles to diffusion. Throughout the course of
thousands of years agriculture began to “diffuse” at different rates. For example food
production in Africa’s great lakes region spread very quickly to southern Nepal very
quickly because both had very similar rainfall regimes. In contrast, between a much
shorter distance between Mexico and the US, the agriculture production was much slower
due to the areas of intervening deserts.
Continental differences in axis orientation affected the diffusion not only of food
production but also of other technologies and inventions. Around 3000 B.C. the
invention of the wheel was spreading rapidly east and west from southeast Asia within a
few centuries while the invention of the wheel in Mexico never spread south to the
Andes. The wheel then served a huge purpose in agriculture by allowing carts to be
drawn by ox and therefore allowing agricultural products to be spread easier.
Among wild plant and animal species only a small portion are edible to humans or worth
hunting/gathering. Most are useless for the following reasons
1) indigestible
2) poisonous
3) low in nutritional value
4) tedious to prepare
5) difficult to gather
6) dangerous to hunt
Most of the biomass on land we can’t digest so by selecting and growing a few
species of plants and animals we can eat so that they take up a larger part of the
biomass on an acre of land. We can obtain more edible calories and as a result feed
many more herders and farmers roughly 10 to 100 times more than hunter gathers.
This resulted in the first military advantage of brute numbers that farmers had over
hunter gathers.
Possession of domestic animals in human society fed more people in 4 distinct
ways.
1) Furnishing meat
2) Milk
3) Fertilizer
4) Pulling plows
Domesticate animals became a major source of animal protein replacing wild game. In
addition some served as sources of mild and milk products, those animals thereby yielded
several times more calories over there life then if they were just slaughtered. They also
interacted with domestic plants in 2 ways.
1) To increase crop production through use of manure applied as fertilizer.
2) By pulling plows and thus making it possible for people to farm land that they
originally could not.
An example is the first prehistoric farmers of central Europe the Linearbandkeramik that
arose slightly before 5000BC only farmed light soils that could be tilled by hand.
All of the above were direct ways lead to denser human population. A more
indirect way was the sedentary lifestyle enforced by food production. Hunter-gathers
moved frequently in search of food where as farmers remained near there fields. This
resulted in a much dense human population from increased birth rates. Hunter-gathers
only had a child once every 4 years where as farmers was half that. Hunter-gathers
spaced their kids out by means of lactational amenorrhea, sexual abstinence, infanticide,
and abortion. By contrast farmers raised as many as they could feed. This let farmers
achieve the higher population densities.
A separate consequence of settled existence was the ability to store food surplus
which is essential for feeding non-food-producing specialist (kings and bureaucrats) and
to support towns. Hence hunter-gatherers had no specialist and no formal type of
government.
Once food can be stockpiled a government can be set up to organize and regulate
such things as political activities and taxation and maintain an army. This gave them the
ability to sustain wars of conquest. By being able to feed there army with stockpiled
food. Stockpiled food also can feed priests for religion, artisan like metalworkers who
develop swords and guns, and scribes who preserve information.
These are not the only uses of crops and livestock, other uses include keeping us
warm from such things as blankets, clothing etc. We are able to make these from the
valuable materials that crops and livestock provide us with. Animals were another
important raw material for artifacts for Neolithic peoples before metallurgy.
Big domestic mammals revolutionized human society by becoming our main
means of land transport. Before animals the backs of humans was the main means of
transport. Large mammals changed that for the first time in human history it was
possible to move heavy goods in large quantities. From this the horse became the chief
means of long distance transport.
The most direct effect of plant and animal domestication to wars was from horses.
Horses became the equivalent to our modern day tanks and jeeps, this allowed many
nations to be conquered with ease like the Aztec and Inca empires. The use of horses
gave the nation using them a huge military advantage over those without them. Another
important factor in wars was germs that evolved in human societies with domestic
animals. Disease like smallpox arose as specialized germs of humans, derived most
likely from ancestral germs of that had infected animals. Hence humans who first
domesticated animals were the first to fall victim to the newly evolved germs but also
built up a resistance to them as well. Humans who had no previous exposure to the
germs resulted in epidemics in which there was a 99% kill rate in the population. These
types of germs played a huge role in the Europeans conquest of Native Americans,
Australians, South Africans and pacific islanders.
To sum it up plant and animal domestication meant more food and hence denser
human populations. This is a prerequisite for the development of a fully function society.
This then explains why empires, literacy and steel weapons developed earliest in Eurasia
and later or not at all one other continent.