"Green thing eaten raw"

Independant centers of crop domestication. Image source: Science Direct, "The Molecular Genetics of Crop Domestication"

Independant centers of crop domestication. Image source: Science Direct, "The Molecular Genetics of Crop Domestication"

Thousands and thousands of years ago, humans began domesticating plants and animals. This happened independently in at least seven areas worldwide as people transitioned from hunter gathering to agrarian societies. Mesoamerica was one of these seven regions, and the birthplace of many beloved foods, including maize, beans, cocoa, cotton and today’s topic: squash

One very old squash seed from at least 8,000 years ago. Image source: ScienceMag,org "Squash seeds quash dissent on New World farming." 

One very old squash seed from at least 8,000 years ago. Image source: ScienceMag,org "Squash seeds quash dissent on New World farming." 

If you live in the Northern hemisphere, you may be tired of eating delicate summer squashes - like zucchini and alien-like pattypans - but winter squash season is just starting. Winter squashes, including acorns, butternuts and hubbards, have thicker skin and can be stored throughout the winter without going bad. On small farms, winter squash harvest takes place all at once towards the end of the season. Good squashes are sorted from bad in the field and then loaded into giant crates to be stored and distributed throughout the winter months. 

Both summer and winter squashes are part of the genera cucurbita. (Watermelons, cucumbers, non-edible gourds and giant pumpkins are related to squash on the family level of classification.) Five species of squash have been domesticated, but the two I’m most interested in – especially for eating – are C. pepo, which includes summer and winter squash, and C. moschata, butternut squash. 

Ancestral species of cucurbits were present in the Americas prior to humans. Domestication of squash from some unknown wild ancestor to the large, fleshy fruits we recognize today took place over 5,000 years ago. Much of the evidence supporting squash domestication is based on excavations from caves in Mesoamerica. These caves were well used by humans and contained plant remnants that span centuries. Artifacts found during the 1950’s, 60’s and 70s’s have been analyzed many times as newer dating technologies are developed. 

The peduncle is the stem coming out of the top of the squash. When a squash is harvested the peduncle is left on to help keep the fruit from rotting. Photo credit: Claire Collie

The peduncle is the stem coming out of the top of the squash. When a squash is harvested the peduncle is left on to help keep the fruit from rotting. Photo credit: Claire Collie

What kind of remnants did ancient squashes leave behind? Namely seeds, bits of rind and peduncles. (The peduncle is the stem bit that is attached to a squash. If you picture a jack-o’-lantern the peduncle is the ‘handle’ you use to take the top off when putting a candle inside.)

In the Ocampo region of Northeast Mexico, evidence from these caves suggests that early users, around 5,000 BP, were mainly hunter-gathers. The presence of C. pepo rinds and seed remnants suggests that these native people did some planting and cultivation. A few thousand years later, around 3500 BP, there were lots of cucurbit remnants found in the caves, as people became more agrarian. Not only did they farm many crops, they also lived in large, stable villages with thatched houses and used ceramics for cooking. 

The title of this post "green thing eaten raw" is the translation from the Narrangansett tongue of the native word for squash, askutasquash, according to Roger Williams. I've tried raw squash, and find it improves with cooking.

How can you tell that a fossilized piece of squash is from a domesticated plant and not some weed-seed that blew in? 

Size. Increasing fruit, seed or root size is usually the goal when cultivating plants for consumption. Humans originally domesticated squashes for their edible seeds. Seeds longer than 12mm are a good indicator that they came from domesticated plants. Thicker peduncles and rind are also indicators of cultivated plants.

A female squash flower with a butternut squash just starting to grow. Photo credit: Claire Collie

A female squash flower with a butternut squash just starting to grow. Photo credit: Claire Collie

How do you domesticate, or selectively breed a squash?

Making squash plants have bigger seeds, as early Mesoamericans did, was probably done much the same way that current squash breeders aim to create new varieties for us today. It all boils down to pollination. 

Squash plants have both female and male flowers. Telling which is which is pretty easy if you look closely. Underneath every female flowers there is a small embryonic fruit, and inside the flower is a stigma. Meanwhile, male flowers are usually atop long stems, and have anthers inside. Pollination of squashes is pretty typical: a bee collects nectar from the male flower and in doing so gets covered in pollen. When it collects nectar in a female flower the pollen is deposited on the stigma, which fertilizes the embryo. 

However, squash breeders may want a particular squash flower to be fertilized with only pollen from a particular other plant. Here’s how to hand pollinate squash: 

A male flower on the left (in the background) atop a long stem. Photo credit: Claire Collie

A male flower on the left (in the background) atop a long stem. Photo credit: Claire Collie

As soon as flowers start to open, find a male flower. Cut it off from the plant where the flower stem meets the main plant stem. Take off all the petals, so you’re left with a plant Q-tip covered in pollen. Next, find a female squash flower and ‘paint’ the stigma inside with the pollen. To keep pesky bees from contaminating the stigma with other pollen, you can tie or tape up the flower. Once the fruit below the flower starts to grow you can give yourself a pat on the back for successfully doing the work of a bee.

This fall when you’re roasting a butternut squash for dinner you’ll know that your meal was thousands of years in the making with the help of a lot of bees and dedicated breeders. Which is mind-boggling enough that you might need a piece of pumpkin pie to muse it over.

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