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Ancient maize genomes! Our new research #openaccess in @PNASNews. There’s a rockshelter in Honduras—El Gigante—with amazing organic preservation of plants. Avocado, squashes and gourds, agave, lots more species spanning the last 11,000 years. https://www.pnas.org/content/early/2020/12/09/2015560117
And, maize. El Gigante has over 10,000 maize cob fragments and seeds beginning a little over 4,000 years ago. We sequenced genomes from 3 of these, and they look surprisingly like modern and ancient maize from South America.
Indigenous cultivators introduced maize to South America in at least two waves, a first very early dispersal around 7,000 years ago, and a later wave of a lineage that’s also widespread in other parts of the Americas. https://science.sciencemag.org/content/362/6420/1309
The El Gigante maize is similar to this second group, the “pan-American” cluster. But more precisely, it resembles the South American members of this cluster, and also carries some ancestry from the first wave that was introduced much earlier to South America.
So these three genomes suggest that Indigenous farmers in South America folded variation from the long-established first wave landraces into newly arriving pan-American maize, and then moved the new hybridized varieties northward again.
This isn’t super surprising. Indigenous farmers introduced Amazonian crops like manioc to Mesoamerica, and of course maize would have moved around quite a lot alongside people and other crops. But we don’t usually get this kind of resolution using archaeology alone.
We can’t say when this happened exactly, although we think it may have been more than 4000 years ago. That’s when maize cultivation and consumption really started to increase in Central America. https://advances.sciencemag.org/content/6/23/eaba3245
We also don’t know how this introduction may have helped shape maize diversity, resilience, productivity, and ultimately its importance for people in Mesoamerica at the time. These are questions for another day, and these genomes open up some exciting new possibilities!
And while we’re here, applications are open until Jan 27 for our 2021 @NMNH REU #NHRE internship program, currently planned to run remotely this summer. Please send your undergrads to apply! https://naturalhistory.si.edu/research/natural-history-research-experiences (end)
