North America’s cradle of civilization can be traced 3,800 years back to the lower Illinois River valley.
It’s there that archaeologists have found evidence of the continent’s first so-called agricultural complex — a set of different crops, rather than a single domesticated plant species.
A rough biological analogue of an agricultural complex is a multicellular animal: It represents a higher level of both complexity and possibility, in which the ability to process more types of energy and better adapt to shifting environmental conditions.
As described Monday in the Proceedings of the National Academy of Sciences, molecular-scale imaging of botanical remains from the Riverton, Illinois archaeological site shows that at least five crops were harvested 3,800 years ago: bottle gourds, sunflowers, marshelders and two varieties of chenopods (pictured at right).
Two other plants, the Cucurbita pepo squash and little barley, appear to have been consumed, though evidence of their domestication is not as clear.
Turn back the clock another 200 years, and no such complex is apparent.
The findings provide an early window into the dietary habits of the region, and could ultimately help anthropological sleuths trace a narrative of cultural evolution from hunter-gatherer to complex society.
In the meantime, they suggest the makings of a retro-historical Thanksgiving feast.