Guns, Germs, and Steel by Jared Diamond Part Two: “How to Make an Almond” The unconscious development of ancient crops

How did certain wild plants get turned into crops? Wild almonds contain cyanide; a few dozen could be lethal – how did they become a crop that we eat today? Wild almonds contain cyanide; a few dozen could be lethal – how did they become a crop that we eat today? Wild corn is much smaller (about a half inch long) than farmed corn – what changes occurred in development of agriculture? Wild corn is much smaller (about a half inch long) than farmed corn – what changes occurred in development of agriculture? Peas were domesticated by 8000 BCE, olives around 4000 BCE, strawberries in the Middle Ages, and pecans not until 1846 – what made some plants so much easier or more inviting to domesticate than others? Peas were domesticated by 8000 BCE, olives around 4000 BCE, strawberries in the Middle Ages, and pecans not until 1846 – what made some plants so much easier or more inviting to domesticate than others?

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

How do plants spread offspring? Get animals to carry seeds by wrapping them in tasty, colorful, and fragrant fruit (but seed themselves are unattractive to eat) Get animals to carry seeds by wrapping them in tasty, colorful, and fragrant fruit (but seed themselves are unattractive to eat) Plants evolve through natural selection; the bigger and riper the fruit, the more likely it will be chosen by an animal and its genes passed on. Plants evolve through natural selection; the bigger and riper the fruit, the more likely it will be chosen by an animal and its genes passed on. Thus, human latrines and garbage dumps may have been a testing ground of the first unconscious crop breeders Thus, human latrines and garbage dumps may have been a testing ground of the first unconscious crop breeders

Almonds Example Almonds are seeds that have evolved to be bitter to discourage animals from eating them. Almonds are seeds that have evolved to be bitter to discourage animals from eating them. A snack of wild almonds contains enough cyanide to kill you. A snack of wild almonds contains enough cyanide to kill you. Individual almond trees have mutations in a single gene that prevents the almonds from producing the bitter cyanide. Individual almond trees have mutations in a single gene that prevents the almonds from producing the bitter cyanide. It is likely that curious children eventually sampled the nonbitter almonds It is likely that curious children eventually sampled the nonbitter almonds

Almonds Example The nonbitter almond trees would be the only ones the ancient farmers planted The nonbitter almond trees would be the only ones the ancient farmers planted By 8000 BCE wild almonds showed up in excavated archaeological sites in Greece By 8000 BCE wild almonds showed up in excavated archaeological sites in Greece By 3000 BCE almonds were being domesticated in the Mediterranean By 3000 BCE almonds were being domesticated in the Mediterranean The Egyptian King Tut was buried with almonds for the afterlife in 1325 The Egyptian King Tut was buried with almonds for the afterlife in 1325

Changes in characteristics that early 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 could not notice Seed dispersal mechanisms Seed dispersal mechanisms Germination inhibition Germination inhibition Reproductive biology Reproductive biology “A tilled, fertilized, watered, weeded garden provides growing conditions very different from those on a dry, unfertilized hillside.”

Stages of Plant Domestication 1. Early crops (such as barley and wheat) that were already edible and gave high yields in the wild. They grew quickly and easily. 2. First fruit and nut trees domesticated around 4000 BCE. Didn’t start to yield fruit until 3 years after planting and did not reach full production for 10 years. 3. Fruit trees that were harder to cultivate planted (through grafting method).

Beyond the Fertile Crescent The sequence of food cultivation is applicable beyond the Fertile Crescent, and involved a combination of the following starter crops: Wheat/barley = grains = fast-growing, high in carbohydrates, high yields (over 50% of all calories consumed by humans) Wheat/barley = grains = fast-growing, high in carbohydrates, high yields (over 50% of all calories consumed by humans) Peas/lentils = pulses = high protein (25 % of protein we eat) Peas/lentils = pulses = high protein (25 % of protein we eat) Fiber crops common across food production beginnings Fiber crops common across food production beginnings

Achievements and Difficulties By Roman times, almost all of today’s leading crops were being cultivated somewhere in the world. By Roman times, almost all of today’s leading crops were being cultivated somewhere in the world. However, there are still plants of value that we have not been able to domesticate. (example: the Oak Tree) However, there are still plants of value that we have not been able to domesticate. (example: the Oak Tree)

Summary Ancient humans selected for certain visible qualities among plant variations (ex: bigger apples). Ancient humans selected for certain visible qualities among plant variations (ex: bigger apples). The evolution of wild plants into crops was unconscious at first. The evolution of wild plants into crops was unconscious at first. Darwin, in his book On the Origin of Species, discussed principals of crop development by artificial selection.