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Artificial selection

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content, procedures, skills

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Tier II: High frequency words used across content areas. Key to understanding directions, understanding relationships, and for making inferences.

Tier III: Low frequency, domain specific terms

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Make connections to prior lessons from this year.
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From Evolution 101: “Long before Darwin and Wallace, farmers and breeders were using the idea of selection to cause major changes in the features of their plants and animals over the course of decades.”

“Farmers and breeders allowed only the plants and animals with desirable characteristics to reproduce, causing the evolution of farm stock. This process is called artificial selection because people (instead of nature) select which organisms get to reproduce.”

“As shown below, farmers have cultivated numerous popular crops from the wild mustard, by artificially selecting for certain attributes. These common vegetables were cultivated from forms of wild mustard. This is evolution through artificial selection.”

Artificial selection of broccoli kale

Image from Evolution 101, evolution.berkeley.edu


Corn has been genetically modified through artificial selection.

That plump ear of corn in the farmer’s market is just as much a product of human engineering as an iPod. Ten thousand years ago, there was no corn — there was just the weedy grass teosinte.

Since then, humans have used evolution’s tool-kit to shape teosinte into the tall stalks of modern corn, joining in the other green revolution — the 6000 years of human history during which we transformed our lifestyles and environments.

Over this time used artificial selection to genetically modify the major crops that we depend upon today: corn, rice, wheat, squash, millet, barley, banana, taro, tomato, potato, beans, and cotton.

Corn teosinte

Image from The other green (r)evolution, Understanding Evolution.


Plants and animals are domesticated through artificial selection,
which works like natural selection does, but with humans instead of nature
doing the selecting. As a simple example, imagine a stand of teosinte plants.

The population varies: some plants are taller, some shorter, some have plumper seeds, some puny seeds, some have more seeds, some fewer (see step 1 below).

Which would you prefer to eat next year? Perhaps, you collect some of the plump seeds and plant them in a convenient location (step 2 below).

The plants that grow from those seeds carry more genes for plumpness
(and have plumper kernels), but they still vary in many ways.
That year, you collect seeds from the few plants in your crop with particularly plump kernels that are easiest to pick off and eat (step 3 below).

The plants that grow from those seeds carry more genes for plumpness and for accessible kernels…and so on.

Over many years of selection, the frequency of desirable gene variants increases in the population — and so does the quality of the crop (step 4 below).

Artifical selection of corn

{ image from University of California Museum of Paleontology’s Understanding Evolution (http://evolution.berkeley.edu). }

Is genetically modified food safe?

It is just as safe as any other food. We already know this, because almost every food we eat is already genetically modified.

Even “natural” and organically grown foods like apples, oranges, tomatoes, corn, broccoli, wheat, and rice were all genetically modified by our ancestors over several thousands years, through a process called artificial selection. This is a process by which humans notice naturally occurring changes in food plants, mutations. Humans then choose what seeds to plant, and not to plant. In the next generation there are also genetic mutations, making subtle differences. Once again, people choose which seeds to plant. Those seeds that are planted have their genetic modifications (mutations) become more common. That is all that there is to evolution


James Kennedy is a Chemistry Teacher at Haileybury, Australia. He created infographics, showing how “natural” foods are in fact genetically modified. And they are just as safe as the natural varieties that used to exist.  Here are a few.

James Kennedy Monash Artificial-vs-natural-foods

artificial-natural-watermelon1 (1)

All of the grains we eat have been genetically modified by thousands of years of artificial selection wheat, barley, rye, spelt and oats.

Consider modern domesticated wheat:




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