Had mastodons, mammoths and giants sloths not gone extinct thousands of years ago, there may not have been enough pumpkins or squash to go around – especially for humans. While early humans did not necessarily eat wild varieties of gourds, large animals, also known as megafauna, often consumed these fruits 12,000 years ago.
"It's been suggested before, and I think it's a very reasonable hypothesis, that wild species of pumpkin and squash weren't used for food early in the domestication process," Logan Kistler, a postdoctoral fellow at Pennsylvania State University, said in a news release. "Rather, they might have been useful for a variety of other purposes like the bottle gourd, as containers, tools, fishnet floats, etc. At some point, as a symbiotic relationship developed, palatability evolved, but the details of that process aren't known at the present."
Humans did not initially take a liking to wild pumpkin and squash, which are members of the cucurbita family, because they were originally bitter and toxic. Today, however, pumpkins and squash are widely consumed – especially during the holiday season.
For their study, researchers from Penn State recovered wild gourd seeds from ancient, preserved mastodon dung and compared them to modern varieties and other archeological specimens. When tracing evolutionary history of gourd seeds, researchers found that the disappearance of large animals directly correlated to changes in distribution of the wild plants.
"We performed an ancient DNA study of cucurbita including modern wild plants, domesticated plants and archaeological samples from multiple locations," George Perry, assistant professor of anthropology and biology, explained in the university's news release. "The results suggest, or confirm, that some lineages domesticated by humans are now extinct in the wild."
When the large animals disappeared the plants grew where the seeded fruit dropped – basically, as far as a pumpkin could roll. These plants became increasingly isolated before eventually going extinct.
Somewhere along the way, pumpkins and squash eventually evolved without their toxicity, which allowed for at least six domestication events and wide-spread consumption.
"There is a huge amount of diversity in some of the domestic species and between them as well," Kistler cocluded. "Cucurbita pepo is probably the most variable, with jack-o-lantern pumpkins, acorn squash, zucchinis and others. Cucurbita moschata contains the butternut squashes and the kind of pumpkin that goes into the cans that a lot of folks will be baking into pies in a few weeks."
Their study was recently published in the journal Proceedings of the National Academy of Sciences.
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