origins of agriculture. david s. seigler department of plant biology university of illinois urbana,...

ORIGINS OF AGRICULTURE

David S. Seigler Department of Plant Biology

University of IllinoisUrbana, Illinois 61801 USA

seigler@life.illinois.eduhttp://www.life.illinois.edu/seigler

Origin of agriculture

• hunter-gatherer societies• past - resources available• sedentary vs. nomadic• cooking and other detoxification methods

• knowledge needed to begin agriculture• theories for how agriculture began• the origins of specific crops

READING

CHAPTER 1: Read over chapter one: Plants and Their Manipulation by People. We will refer to material from this chapter throughout the semester.

CHAPTER 2: Origins of Agriculture.

Introduction

Important points to consider:

• We are absolutely dependent on plants.• Ultimately, only plants can "harvest" the sun's energy by photosynthesis.

• All nutrients and energy are cycled.

• Although we tend to think that we are less dependent on plants today, this is partly a U.S. and European bias. This is not true for most people in the world. We are dependent on fewer species of plants than formerly, but even in the U.S. we are highly dependent on plants.

• Petroleum is the remains of former plants. What will we do when we use it up?

• In this course, we will talk about domesticated plants, gathered plants, and wild plants.

• Perhaps 10,000 plants (of possibly 350,000) are used by the peoples of the earth, but all human civilization depends mostly on 10 or fewer.

Processing of foods

• Cooking makes foods more edible• There is an association of cooking and detoxification of plants.• Cooking made more plants usable by humans.• Cooking arose before agriculture.• Humans were using fire as much as one million years ago

• The cultivation of plants began about 17,000 years ago.

• Evidence for domestication of plants goes back to about 12,000 years ago.

• Text: page 41 ff. on dating methods.

• There were, perhaps, 10,000,000 people on earth at that time. By 2000 years ago, most of the major peoples and regions of the earth practiced agriculture.

• By 1900, there were 1.6 X109 people. Today there are about 6 X 109.

Before agriculture, humans were hunter-gatherers.

• By 1900, hunter-gatherer societies were restricted to small areas that were too dry, too cold or too wet for agriculture.

• In good areas, people of hunter-gatherer societies don't have to learn to plant.

• Many hunter-gatherer societies know all they need to know about growing plants, but don't.

• Some gatherers do plant seeds. Some gatherers replant parts of root crops.

• Most cultures are based on seeds, not root crops, although many root crops are important in the lowland tropics.

• Some gatherers also irrigate. • Gatherers learned how to cook or otherwise detoxify food plants.

• Our system requires energy input, whereas gathering produces excess energy.

Ethnobotanical humor

• There was an association of agriculture and sedentary society.

• Cultivation may have arisen in the zones between sedentary and hunter-gatherer societies.

• Agriculture never arose in California and in the sub Saharan African savanna.

• On the other hand, some sedentary people never developed agriculture (e.g., fishermen).

• Studies of present day hunter-gatherers indicate that they have considerable leisure time.• Until recently, the !Kung bushmen of the Kalahari desert were gatherers. They mostly ate 14 plants. They recognized 105 species of edible plants. Their diet was quite good in protein and in total calories. They worked about 2.5 days per week to gather food.• Agricultural societies work harder.

• Most hunter-gatherers eat (ate) plants. How do we know that? 12C/13C ratios, dentition, abrasion on teeth. Archaeology.

• Meat was an occasional luxury.

• Populations of hunter-gatherer peoples usually are maintained below the carrying capacity.

Origin(s) of agriculture?

• Why did agriculture arise?• Where did agriculture begin? Almost all of the oldest records are from the Near East.

• How do we know the plants they used were cultivated?

• Domesticated animals (dog, sheep, goat, cow) all arose about the same time as domestication of plants. Only about 50 animals were ever domesticated.

• Animals may have been linked to religion.

• Animals were used to till fields mostly in the Old World.

Domesticated animals

• Did agriculture arise as an extension of gathering?

1. religious: Many peoples viewed agriculture as a gift from the gods. Some have felt that agriculture arose for religious reasons, i.e., for sacrifices (more probable for animals).

2. "genius" or "eureka" theory (see "The Source" Mitchener).

Theories of origin of plant domestication

More theories ….

3. refuse heaps - Edgar Anderson. This might have been especially true around houses or cattle pens. Both are also disturbed areas. Parts of the plants that were utilized were often discarded.

4. Carl O. Sauer felt man had to be sedentary first. He favored SE Asia as the place of origin. But many nomadic peoples grow plants for food. The Near East center clearly did not develop in the tropics.

5. Edgar Anderson saw weeds as potential domesticates. They "preferred" disturbed habitats.

Even more theories ….

Origins of particular cropsAlphonse De Candolle - in 1882, wrote a book on the origin of cultivated plants. He based his ideas on historical writings, archaeological information, ethnological data, linguistics etc.

(1806-1893)

N. I. Vavilov

• N. I. Vavilov - added genetics, chromosome studies, and anatomical data. He was interested in the presence of wild ancestors.

• Vavilov concluded that the most likely areas of origin were where the plant was cultivated and the wild ancestors grew.

• Further, the areas of origin should be areas in which there was lots of variation. He decided that there were 8 major areas that met these requirements.

Vavilov’s Centers

• These were: Mexico and Central America, the Central Andes, Abyssinia, the Mediterranean, Indian (Middle East), SW Asia, China, and SE Asia.• Later, he added more till he got up to about 20 or so. At this point you couldn't really call all of them "centers".

Nicholai Vavilov

(1887 – 1943)

Vavilov’s Centers

Harlan concluded that there were three "centers": the Near East, Northern China, and Meso-America and three other areas with diffuse origins (S.E. Asia, S. America, and much of Africa) that he called "non-centers".

Further, it had become clear that a "center of origin" often was not the same as a "center of diversity". Harlan concluded that it is very difficult to separate the origin and later expansion of a successful crop.

Jack Harlan

Jack Harlan

J. R. Harlan, Plant Scientists. Franklin Watts. New York. 1964.

(1917–1998)

Harlan’s Centers and Non-centers

Every model generated so far has evidence for and against it.

Some were for ritual, magic, ceremony, or religious sacrifice. Some were from "dumps". Some weeds gave rise to crops. Some crops gave rise to weeds. Some weed-crop complexes had common progenitors. Some crops arose in Vavilov's centers, some did not.Some people were sedentary before agriculture. Harlan proposed a "no-model" model. That is, he left room for a whole array of motives, actions, practices, and evolutionary processes.

Early agriculture

Many people with hunter-gatherer life styles used fire to control or manage both plants and animals in their area. This became common at the end of the Pleistocene Epoch about 11,700 years ago.

Much agriculture by so-called primitive peoples today is of the slash-and-burn type.

Prairies and savannahs are difficult to farm. Much agriculture is on the margin of forested lands.

The advent of the steel plow made possible settlement of the prairies and plains in the U.S. and Canada in the middle 1800's.

Burning forest in Madagascar

Courtesy Dr. Voara Randrianasolo

Fields in Madagascar

Courtesy Dr. Voara Randrianasolo

Preparing the field

Planting the crops

Slash and burn agriculture in Venezuela

Egyptian agriculture

B. Lehane, Power of Plants, McGraw Hill. New York. 1977

Plowing in Bengla Desh

Courtesy Dr. Ted Hymowitz