Humans thousands of years ago were not big eaters of wild pumpkins or other members of the Cucurbita genus. Rather, it was the megafauna – animals like the mastodon, giant sloth, and mammoth – that played an important role in the dispersal and survival of these wild plants. Anthropologists from Penn State have recently released a study they did on ancient mastodon dung in which they found pumpkin seeds to be present. They hypothesized that some species of Cucurbita are no longer found in the wild today due to the disappearance of these megafauna about 12,000 years ago.
These early humans, as well as smaller mammals, would not have been interested in wild Cucurbita due to its strong bitter taste. Bitter taste receptors help humans and other animals detect and stay away from foods that may be toxic. However, this study finds that larger mammals do have as good bitter taste receptors and so would not have strayed from wild Cucurbita species as humans would have. With these wild pumpkins, squash, and gourds as a part of the megafauna diet the plant seeds would be widely dispersed as the megafauna carry them on their travels, similar to how bees inadvertently spread pollen between flowers as they search for nectar. This symbiotic relationship between megafauna and wild Cucurbita collapsed when the megafauna disappeared about 12,000 years ago due to ecological shifts and human predation. With no mechanism to help spread the Cucurbita seeds they could no longer thrive.
The study suggests the only reason we can enjoy pumpkins today is due to a mutation that might have left a few Cucurbita species less bitter than others. These mutations were domesticated by humans and became the squash we enjoy today, the wild bitter Cucurbita disappearing with the mastodon.
