Agricultural Legacies

Disease, Writing, and Technology in Eurasia

Population DensityAgriculture does not produce better people; it produces more dense populations.

This density will tend to favor the agricultural populations in head-to-head conflicts with hunter-gatherers.

Bantu Migration

But these societies not only produce greater population density, they produce more lethal diseases.

The major killers of humanity throughout our recent history—smallpox, flu, tuberculosis, malaria, plague, measles, and cholera—are infectious disease that evolved from diseases of animals.

The germ’s strategies:Passively wait for the next victim.

Wait for one victim to be eaten by the next victim. Salmonella bacteria, e.g., is consumed by eating infected eggs or meat. Trichinosis worm gets from pigs to us by our eating the pigs.

Hitchhike on the saliva of an insect (bites old host, flies off to infect new host).

Mosquitoes, fleas, lice, tsetse flies (et al) which spread diseases like malaria, plague, typhus, or sleeping sickness. Some hitchhike from mother to fetus, like AIDS, rubella, and syphilis.

Inducing coughing or sneezing is a more aggressive strategy.

Influenza, common cold, pertussis (whooping cough) Inducing diarrhea is a similar strategy: cholera. Rabies actually changes the host’s behavior (biting new victims ) in order to use the saliva. Hookworms burrow through the skin of their victims.

Fighting back:

Develop a fever. Mobilize our immune systems.

In the cases of illnesses like measles, mumps, rubella, pertussis, and smallpox, one exposure confers immunity forever (hence vaccinations). Our resistance to flu and the common cold is only temporary. New strains evolve. Malaria and sleeping sickness are able to rapidly change their antigens. They are very difficult to battle.

Natural selection can be effective, but over subsequent generations.

Sometimes this comes at a cost: e.g., the way the sickle-cell gene, Tay-Sachs gene, and cystic fibrosis may confer on African blacks, Ashkenazi Jews, and Northern Europeans some immunity against malaria, tuberculosis, and bacterial diarrheas.

Epidemics

Epidemic diseases produce no cases for a long time, then a whole wave of cases, then no more cases for awhile. Great Influenza Epidemic (during WWI): killed 21 million.

Black Death killed as much as half the population of Eurasia.

In the 1880’s Indigenous peoples in Saskatchewan died at a rate of 9%/year.

Epidemic diseases share several characteristics:

1. Spread quickly and efficiently form infected person to healthy person with the result that an entire population is exposed in a brief time.

2. They are acute diseases. Within a short time you either die or get better.

3. Those who recover develop antibodies that leave them immune for a long a time, possibly for the rest of their lives.

4. These diseases tend to be restricted to humans.

Because this is how they spread, they die out when they have ravaged a population and can’t return until there is a new generation of susceptible victims. Small bands of hunter-gatherers and slash-and-burn farmers could not be sites of sustaining such epidemics. Not only can they not sustain epidemic diseases, such diseases cannot evolve in such small groups of people. The Faeroes Measles Epidemics of 1781 and 1846. (A severe epidemic reached these people in 1781, died out, and then returned with an infected Danish carpenter.)

Why do diseases arise only among agricultural communities with dense, larger, settled populations? Because such denser populations are the only ones that can sustain such epidemics. Because farmers are settled, living among their own sewage. The development of world trade routes allows them to spread from one population to another. Because settled agriculturalists live among animals.For epidemics to develop among animals, they also require dense populations. The evolve among herd animals—exactly the kind that humans have domesticated. They were already afflicted by these epidemics, waiting for them to evolve in a form that could attack humans.

Four stages in the evolutions of specialized human disease from an animal precursor:

1. Diseases picked up directly from animals. For example, diseases we now pick up from our pets: cat-scratch fever, leptospirosis (from dogs), psittacosis (from chickens and parrots), brucellosis (from cattle). We can also pick up diseases from wild animals.

2. A former animal pathogen evolves to the point where it does get transmitted directly between people and causes epidemics, but dies out. O’nyong-nyong fever (East Africa 1959), Fort Bragg fever (1942).

3. Former animal pathogens that did establish themselves in humans, that have not (yet?) died out, and that may or may not still become major killers of humanity. (Lassa fever, Lyme disease)

4. Long established epidemic diseases confined to humans.

Eurasian disease and the Conquest of the AmericasSmallpox reached Mexico in 1520 and killed half the Aztecs.By 1618 Mexico’s population had plummeted from 20 million to 1.6 million. Hernando de Soto (1540) encountered sites in the Southeastern U.S. that were essentially depopulated. The relics are the Great Mound Sites of the Mississippi Valley. Disease may have killed as much as 95% of the Indigenous population of North America. In the Americas denser populations didn’t emerge until very late (1000 years ago) and trade routes were later, slower, and less complete. Llamas had four strikes against them as a source of human pathogens:

1. Kept in smaller herds than sheep, pigs, and goats.2. Total numbers were never remotely as large as European domestic animal

populations.3. They never spread beyond the Andes.4. Llamas aren’t kept indoors.

By contrast, Europeans encountered “tropical diseases” such as malaria, cholera, and yellow fever in Africa, Indonesia, and Southeast Asia.

Writing . . . Begins with tokens:

Knowledge brings power. Writing facilitated this rise in communication, bureaucracy, information, and control.

Invention of writing:Sumerians (before 3000 BCE)Mexican Indians (before 600 BCE)Egyptian (3000 BCE)Chinese (by 1300 BCE)

Three basic strategies underlying a writing system:Single sound

Whole syllableWhole word

Common syllaberies:

Linear B (Mycenaean Greece)Kana system still used for Japanese in telegrams, bank statements, etc.

Sumerian writing was a mixture of logograms, phonetic signs, and determinatives (unpronounced but used to resolve ambiguities). About a dozen Mesoamerican scripts are known, all/most apparently related.

Maya phonetic signs were mostly signs for syllables of one consonant plus one vowel. Chinese and Egyptian tend to be logograms. Alphabetic writing evolved and included three further important developments:

Restricting signs to those for a single consonant.Organize letters in a memorable sequence.Provide for vowels.

Pictograms:

Cuneiform:

Hieroglyphics:

The decision to move to a writing system seems to have been driven initially by accounting concerns; it was a technology of power. According to Claude Levi-Strauss, ancient writing’s main functions was “to facilitate the enslavement of other human beings.”

Use of tokens.Prevalence of accounting records in Linear B.Remember Iliad and Odyssey were initially oral traditions.

We do have a line of poetry on an Athenian wine jug from around 740 BCE.

Diamond thinks this shows that alphabets were first used for personal communication and only later became bureaucratic tools.

Writing was never adapted by hunter-gathers because they lacked both the institutional uses of early writing and the social and agricultural mechanisms for generating the food surpluses required to feed scribes. Food production is a necessary, but not a sufficient cause for the development of writing. We also need to remember that the vast majority of societies acquired writing by borrowing it from their neighbors.

Agrarian Civilizations also create more powerful technologies . . .

Most of the history of invention is not the history of necessity giving birth to invention, but of invention in search of necessity.

Also, all recognized famous inventors had capable predecessors and successors and made their improvements at a time when society was capable of using their product. So, technology develops cumulatively, rather than in isolated heroic acts, and that it finds most of its uses after it has been invented, rather than the other way around. (Jared Diamond)

Factors influencing the acceptance of inventions:1. Relative economic advantage compared with existing technology. (A

wheel wouldn't be much help to Americans who had no animals to hitch to their carts.)

2. Social value and prestige. (Example, designer jeans.)3. Compatibility with vested interests. (QWERTY keyboard)4. Ease with which their advantages can be considered.

Factors influencing receptivity of new technologies:• Availability of cheap slave labor.• Patents and other property laws.• Opportunities for technical training.• Emphasis on individualism.• Propensity for risk-taking behavior.• A scientific outlook.• Religious attitudes.• War as stimulant to technological development.• Wars as setbacks.• Strong centralized government. (can be pro or against)• Environment (open to interpretation)• Natural resources (open to interpretation)

Technologies can also be abandoned: e.g., Japan’s abandonment of guns. Diamond argues that technological development is an autocatalytic process, speeding up with time. Metallurgy grew out of experience with metals melted by naturally-occurring fires.

It also grew out of thousands of years of experience creating ovens for pottery making.