Plant and animal domestication
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Plant and Animal Domestication. Jared Diamond, Guns, Germs, and Steel. Why Farm?. Hunting and gathering can supply a day’s calories with a couple of hours’ work Many early farmers less well off than hunter-gatherers Line between hunter-gatherers and farmers is fuzzy

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Plant and Animal Domestication

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Plant and animal domestication

Plant and Animal Domestication


Jared diamond guns germs and steel

Jared Diamond, Guns, Germs, and Steel


Why farm

Why Farm?

  • Hunting and gathering can supply a day’s calories with a couple of hours’ work

  • Many early farmers less well off than hunter-gatherers

  • Line between hunter-gatherers and farmers is fuzzy

    • In rich environments, hunter-gatherers may have permanent settlements (Pacific Northwest)

    • May practice some agriculture along with hunting and gathering (Apaches)


The ice age and agriculture

The Ice Age and Agriculture

  • Sea level rise stops about 7000 years ago

  • Agriculture spreads widely roughly same time

  • Stable coastal plain and river valley environments

  • Warm, dry climate favors spread of wild grains

  • Extinction of megafauna (and domestication candidates?)


Mediterranean climate

Mediterranean Climate

  • Dry Summer, Rainy Winter

  • Favors plants with seeds that can survive long dry periods

  • These seeds can be stored for extended periods

  • Will not spoil or germinate while dry

  • Eurasian Mediterranean is world’s largest zone, greatest ecological diversity in small areas


The fertile crescent

The Fertile Crescent


Large seed grasses

Large Seed Grasses

  • 56 species, <1% of total grass species

  • Eurasian Mediterranean 32 species

  • Rest of Eurasia 7 species

  • Sub-Saharan Africa 4 species

  • North America 4 species

  • Mesoamerica 5 species

  • South America 2 species

  • Australia 2 species


Human plant environments

Human Plant Environments

  • Select desirable plants in wild

  • Some seeds, fruits scattered at habitation site

  • Other seeds deposited in wastes

  • Eventually have desirable plants growing close-by

  • Protection from foragers

  • Seed collection


Plant domestication

Plant Domestication

  • More than just planting seeds or transplanting

  • Most plants inedible or otherwise unusable

  • Most plants unsuited for primitive domestication

  • Not every locality has abundant plants suitable for human use

  • Need nutritional balance

  • Requires changes in plant characteristics


Highland new guinea

Highland New Guinea

  • Simple agriculture for thousands of years

  • Active experimentation and inquiry

  • Chronic protein deficiency

  • Introduction of sweet potato (South America via Philippines) caused population boom

  • These people knew their environment as well as any people on earth

  • If any local plants could have been successfully domesticated, they would have found them


Five levels of domestication

Five Levels of Domestication

  • Unconscious selection of plants for desirable traits (9000 BC)

  • Conscious cultivation of plants with desired traits (BC)

  • Deliberate breeding to improve traits (1700)

  • Scientific breeding: genetic mechanism known and exploited (1900)

  • Direct genetic manipulation (2000)


Reversing natural selection

Reversing Natural Selection

Seed Scattering

  • Non-bursting pods (peas)

  • Non-shattering heads (grains)

  • Fruits without seeds

    Germination Inhibition

  • Nature: favors seeds that germinate slowly and over time

  • Agriculture: favors seeds that germinate quickly all at once


Reversing natural selection1

Reversing Natural Selection

Deterrents

  • Loss of Toxicity (Almonds)

    Changes in Reproduction

  • Asexual Reproduction

  • Self-Fertilization (Hermaphrodites)

    Annuals favored: would evolve more quickly under artificial selection


Plant domestication1

Plant Domestication

  • Single Mutation

    • Chance of getting multiple favorable mutations very slim

  • Self-Pollinated or Asexual Reproduction

    • Pollination from elsewhere would negate mutation


Some non domesticates

Some Non-Domesticates

Oaks

  • Food Source in Many Places

  • Grow Slowly

  • Bitterness Controlled By Many Genes

  • Seed Dispersal by Animals

    Berries

  • Seed Dispersal by Animals

  • Domesticated only after greenhouses invented


Fertile crescent founder crops

Fertile Crescent Founder Crops

  • Emmer Wheat

  • Einkorn Wheat

  • Barley

  • Lentil

  • Pea

  • Chickpea

  • Bitter Vetch

  • Flax


North american crops

North American Crops

  • Gourds

  • Sunflower

  • Sumpweed (seed crop)

  • Goosefoot (leaf crop)

  • Corn (from Mexico)

  • Beans (from Mexico)

  • Squash (from Mexico)


Agriculture and civilization

Agriculture and Civilization

Why the Link?

  • Need for organization, surveying, record-keeping

  • Surpluses allow development of specialist classes

  • Protection?

    • Grain stores susceptible to raiding


Animal domestication

Animal Domestication

  • Genetic change that makes animal more amenable to human control

  • Not the same as:

    • Taming

    • Training

    • Captive Breeding

  • A lot more complicated than just capturing and taming animals


Animal domestication1

Animal Domestication

Happy families are all alike. Every unhappy family is unhappy in its own way.

--Tolstoy, Anna Karenina

Lots of things have to work for success. Failure in any one means failure of it all.


Unsuitable for domestication

Unsuitable for Domestication

  • Ferocity (Zebras, Rhinos, Hippos)

  • High Trophic Level (Carnivores)

  • Picky Diet (Pandas, Koalas)

  • Slow Growth (Elephants)

  • Territoriality (Deer, Antelope)

    • Large Range

    • Solitary Habits

  • Reclusive Breeding or Elaborate Courtship (Cheetahs)

  • Tendency to Panic (Gazelles)


Suitable for domestication

Suitable for Domestication

  • Docile (or selectable for docility)

  • Non-territorial

  • Dominance Heirarchy (Humans co-opt leadership role)

  • Uninhibited Breeding

  • Rapid Growth a plus


Thyroxine

Thyroxine

  • Governs many growth and maturation characteristics

  • Governs adrenaline (fear response)

  • Low thyroxine traits:

    • Reduced snout (pedomorphism)

    • Solid or patchy colors

    • More frequent reproduction

    • Larger litters


Self domestication

Self-Domestication

Humans create an environment

  • Free of Predators

  • Abundant food

  • Salt


Animal domestication2

Animal Domestication

  • 148 Species of Large Herbivores (>50 kg)

  • Eurasia 13/72 (18%) Domesticated

  • Sub-Saharan Africa 0/51 Domesticated

  • Americas 1/24 (4%) Domesticated

  • Australia 0/1 Domesticated


The big five

The Big Five

  • Sheep

  • Goat

  • Cattle, Oxen

  • Pig (Actually an Omnivore)

  • Horse

  • All are Eurasian


The lesser nine

The Lesser Nine

  • Arabian and Bactrian Camels (Eurasia)

  • Donkey (Eurasia)

  • Water Buffalo (Eurasia)

  • Yak (Eurasia)

  • Bali Cattle, Mithan (Eurasia)

  • Reindeer (Eurasia)

  • Llama (including Alpaca) (South America)


Why eurasia

Why Eurasia?


Why eurasia1

Why Eurasia?

  • Only Land Mass with east-west axis

  • Other barriers

    • Panama and Caribbean

    • Rain Forest (Africa)

    • Trypanosome Belt (Africa)

  • Extinction of Megafaunas

    • Not adapted to humans and vice versa

    • Possible candidates for domestication wiped out?


Why not domestication

Why Not Domestication?

  • Buffalo (bison) and elk successfully farmed in modern times

  • Have attributes that seem promising for domestication

  • Wild grapes in America not cultivated

  • If advantages marginal, domestication may not happen even if possible

  • Indians adapted to Horses Very Quickly


Domesticated carnivores

Domesticated Carnivores

  • Dogs

    • Have dominance hierarchy that humans can co-opt

  • Cats

    • Probably attracted to prey around grain stores

    • At best partially domesticated

  • Ferrets

    • Recently popular as pets but long used for pest control

    • Probably many of same factors as cats


Small animal domestication

Small Animal Domestication

  • Thousands of Candidates

  • Distinction between Domestication and Captive Rearing fuzzier

    • Do We Really Care if a Rabbit is Captive or Domesticated?

  • Very Rapid Breeding Cycle


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