Guns, Germs, and SteelGuns, Germs, and Steelby Jared Diamondby Jared Diamond

Part Two: “How to Make an Almond”Part Two: “How to Make an Almond”The unconscious development of The unconscious development of

ancient cropsancient crops

How did certain wild plants get How did certain wild plants get turned into crops?turned into crops?

Wild almonds contain cyanide; a few dozen could be Wild almonds contain cyanide; a few dozen could be lethal – how did they become a crop that we eat lethal – how did they become a crop that we eat today?today?

Wild corn is much smaller (about a half inch long) Wild corn is much smaller (about a half inch long) than farmed corn – what changes occurred in than farmed corn – what changes occurred in development of agriculture?development of agriculture?

Peas were domesticated by 8000 BCE, olives around Peas were domesticated by 8000 BCE, olives around 4000 BCE, strawberries in the Middle Ages, and 4000 BCE, strawberries in the Middle Ages, and pecans not until 1846 – what made some plants so pecans not until 1846 – what made some plants so much easier or more inviting to domesticate than much easier or more inviting to domesticate than others?others?

Definition: DOMESTICATEDefinition: DOMESTICATE

Plant domestication is growing a plant and Plant domestication is growing a plant and thereby, consciously or unconsciously, causing thereby, consciously or unconsciously, causing it to change genetically from its wild ancestor it to change genetically from its wild ancestor in ways making it more useful to human in ways making it more useful to human consumers.consumers.

How do plants spread offspring? How do plants spread offspring?

Get animals to carry seeds by wrapping them in tasty, Get animals to carry seeds by wrapping them in tasty, colorful, and fragrant fruit (but seed themselves are colorful, and fragrant fruit (but seed themselves are unattractive to eat)unattractive to eat)

Plants evolve through natural selection; the bigger Plants evolve through natural selection; the bigger and riper the fruit, the more likely it will be chosen by and riper the fruit, the more likely it will be chosen by an animal and its genes passed on.an animal and its genes passed on.

Thus, human latrines and garbage dumps may have Thus, human latrines and garbage dumps may have been a testing ground of the first unconscious crop been a testing ground of the first unconscious crop breedersbreeders

Almonds ExampleAlmonds Example

Almonds are seeds that have evolved to be Almonds are seeds that have evolved to be bitter to discourage animals from eating them.bitter to discourage animals from eating them.

A snack of wild almonds contains enough A snack of wild almonds contains enough cyanide to kill you.cyanide to kill you.

Individual almond trees have mutations in a Individual almond trees have mutations in a single gene that prevents the almonds from single gene that prevents the almonds from producing the bitter cyanide.producing the bitter cyanide.

It is likely that curious children eventually It is likely that curious children eventually sampled the nonbitter almondssampled the nonbitter almonds

Almonds ExampleAlmonds Example

The nonbitter almond trees would be the only The nonbitter almond trees would be the only ones the ancient farmers plantedones the ancient farmers planted

By 8000 BCE wild almonds showed up in By 8000 BCE wild almonds showed up in excavated archaeological sites in Greeceexcavated archaeological sites in Greece

By 3000 BCE almonds were being By 3000 BCE almonds were being domesticated in the Mediterraneandomesticated in the Mediterranean

The Egyptian King Tut was buried with The Egyptian King Tut was buried with almonds for the afterlife in 1325almonds for the afterlife in 1325

Changes in characteristics that early Changes in characteristics that early farmers could notice:farmers could notice:

Fruit size (strawberries)Fruit size (strawberries) Bitterness (almonds)Bitterness (almonds) Fleshiness (squash)Fleshiness (squash) Oiliness (olives)Oiliness (olives) Fiber length (flax)Fiber length (flax)

Changes in early crops that farmers Changes in early crops that farmers could not noticecould not notice

Seed dispersal mechanismsSeed dispersal mechanisms Germination inhibitionGermination inhibition Reproductive biologyReproductive biology

““A tilled, fertilized, watered, weeded garden A tilled, fertilized, watered, weeded garden provides growing conditions very different provides growing conditions very different from those on a dry, unfertilized hillside.”from those on a dry, unfertilized hillside.”

Stages of Plant DomesticationStages of Plant Domestication

1.1. Early crops (such as barley and wheat) that Early crops (such as barley and wheat) that were already edible and gave high yields in were already edible and gave high yields in the wild. They grew quickly and easily.the wild. They grew quickly and easily.

2.2. First fruit and nut trees domesticated around First fruit and nut trees domesticated around 4000 BCE. Didn’t start to yield fruit until 3 4000 BCE. Didn’t start to yield fruit until 3 years after planting and did not reach full years after planting and did not reach full production for 10 years.production for 10 years.

3.3. Fruit trees that were harder to cultivate Fruit trees that were harder to cultivate planted (through grafting method).planted (through grafting method).

Beyond the Fertile CrescentBeyond the Fertile Crescent

The sequence of food cultivation is applicable The sequence of food cultivation is applicable beyond the Fertile Crescent, and involved a beyond the Fertile Crescent, and involved a combination of the following starter crops:combination of the following starter crops: Wheat/barley = grains = fast-growing, high in Wheat/barley = grains = fast-growing, high in

carbohydrates, high yields (over 50% of all carbohydrates, high yields (over 50% of all calories consumed by humans)calories consumed by humans)

Peas/lentils = pulses = high protein (25 % of Peas/lentils = pulses = high protein (25 % of protein we eat)protein we eat)

Fiber crops common across food production Fiber crops common across food production beginningsbeginnings

Achievements and DifficultiesAchievements and Difficulties

By Roman times, almost all of today’s leading By Roman times, almost all of today’s leading crops were being cultivated somewhere in the crops were being cultivated somewhere in the world. world.

However, there are still plants of value that we However, there are still plants of value that we have not been able to domesticate. (example: have not been able to domesticate. (example: the Oak Tree)the Oak Tree)

SummarySummary

Ancient humans selected for certain visible Ancient humans selected for certain visible qualities among plant variations (ex: bigger qualities among plant variations (ex: bigger apples).apples).

The evolution of wild plants into crops was The evolution of wild plants into crops was unconscious at first.unconscious at first.

Darwin, in his book Darwin, in his book On the Origin of SpeciesOn the Origin of Species, discussed , discussed principals of crop development by artificial selection.principals of crop development by artificial selection.