2,000 years ago, people domesticated these plants. Now they’re wild weeds. What happened?
Ars Technica said:Adventurers and archaeologists have spent centuries searching for lost cities in the Americas. But over the past decade, they’ve started finding something else: lost farms.
Over 2,000 years ago in North America, indigenous people domesticated plants that are now part of our everyday diets, such as squashes and sunflowers. But they also bred crops that have since returned to the wild. These include erect knotweed (not to be confused with its invasive cousin, Asian knotweed), goosefoot, little barley, marsh elder, and maygrass. We haven’t simply lost a few plant strains: an entire cuisine with its own kinds of flavors and baked goods has simply disappeared.
By studying lost crops, archaeologists learn about everyday life in the ancient Woodland culture of the Americas, including how people ate plants that we call weeds today. But these plants also give us a window on social networks. Scientists can track the spread of cultivated seeds from one tiny settlement to the next in the vast region that would one day be known as the United States. This reveals which groups were connected culturally and how they formed alliances through food and farming.
Natalie Mueller is an archaeobotanist at Cornell University who has spent years hunting for erect knotweed across the southern US and up into Ohio and Illinois. She calls her quest the “Survey for Lost Crops,” and admits cheerfully that its members consist of her and “whoever I can drag along.” She’s published papers about her work in Nature, but also she spins yarns about her hot, bug-infested summer expeditions for lost farms on her blog. There, photographs of the rare wild plants are interspersed with humorous musings on contemporary local food delicacies like pickle pops.
Indigenous to the Americas, erect knotweed grows in the moist flood zones near rivers. It’s a stalky plant with spoon-shaped leaves, and it produces achenes, or fruit with very hard shells to protect its rich, starchy seeds. Though rare today, the plant was common enough 2,000 years ago that paleo-Americans collected it from the shores of rivers and brought it with them to the uplands for cultivation. Archaeologists have found caches of knotweed seeds buried in caves, clearly stored for a later use that never came. And, in the remains of ancient fires, they’ve found burned erect knotweed fruits, popped like corn.
Mueller told Ars Technica that erect knotweed was likely domesticated on tiny farms on the western front of the Appalachians. There are clear differences between it and its feral cousins. After years of comparing the ancient seeds with wild types, Mueller has found two unmistakable signs of domestication: larger fruits and thinner fruit skins. We see a similar pattern in other domesticated plants like corn, whose wild version with tiny seeds is almost unrecognizable to people chomping on the juicy, large kernels of the domesticated plant.
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