Pumpkin Eater

Other than the turkey itself, no other foodstuff says Thanksgiving like pumpkin. Notably, both the turkey and the pumpkin are native to the Americas. Turkeys and pumpkins both were supposedly components of that first meal shared by native Americans with the colonists. Pumpkin pie is so ubiquitous that the combination of spices used to flavor it – cinnamon, nutmeg, cloves, and ginger – have come to be called pumpkin spice, and that flavor shows up in a number of the products we consume this time of year.

Pumpkins are in a large family, Cucurbita, with over 900 species. These species include gourds, winter and summer squash, all sorts of melons, and even cucumbers. Native Americans over thousands of years transformed what we know today as a Pumpkin from a tennis ball sized gourd with a very bitter taste.

As are so many other things we eat, pumpkins were made palatable via selective breeding. Pumpkins originated in Central America, and seeds of domestic Pumpkins dated to 8,000 years Before the Current Era (BCE) have been found in the highlands of Mexico. Softer, sweeter pumpkins were chosen from the wild or selected from purposeful plantings. This process continues to this day. Burpee’s Catalog offers 26 varieties of pumpkins.

The story of the post-human-manipulation pumpkin is interesting in and of itself but the natural history of the pre-humanpumpkin is also exciting. There is evidence that megafauna: mastodons, mammoths, giant sloths, etc., were an important part of the pumpkin’s story. Deposits of mastodon dung dated to 30,000 years ago contained squash seeds. The survival of the seeds after passage through the digestive tract of the megafauna provided a means of dispersal and fertilization which is valuable mechanism for evolutionary success.

It is quite likely that the bitter taste is important to this story. The bitterness of the ancestral pumpkin was due to compound called Curcubitacin which not only imparted the bitter taste but was also toxic. Plants and animals have been duking it out over billions of years. Plants have evolved to produce a great number of toxins to prevent herbivores from damaging their reproductive parts or seeds.

Had small mammals eaten these squash, they surely would have also eaten the nutritious seeds. And here is where the bitterness comes in. Modern gene sequencing has shown that among mammals at least, there is a correlation between sensitivity to the bitter taste and size. Sampling animals from rodents to elephants has shown that the smaller the animal, the greater the sensitivity to bitterness. Small mammals such as rodents avoided the bitter plants leaving them to the megafauna.

The effect is that early pumpkins allied with the megafauna to promote a type of mutualism. The megafauna got the benefit of the pumpkin as food while the pumpkin benefited by dispersion/fertilization. The demise of the megafauna would have been a problem for pumpkins, but luckily humans came along and partnered up. Pumpkins are now cultivated around the world, a range far in excess of its ancestral home.

Dr. Bob Allen is Emeritus Professor of Chemistry, Arkansas Tech University.

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