Principal Investigator: Brian Stewart
Understanding the origins of our species is one of humanity’s great scientific puzzles. Leveraging recent methodological breakthroughs, this Klinsky Expedition will shed much-needed light on this critical issue by extracting ancient human DNA (aDNA) trapped inside items of jewelry worn by our early ancestors and incorporated into the sediments of archaeological sites they inhabited.
For more than half a century, debates raged over where and when Homo sapiens evolved its uniquely “modern” anatomical form, cognitive capacity, and behavioral repertoire. Today, the genetic, fossil, and archaeological records are in full agreement that, firstly, our species evolved—both biologically and behaviorally—inside of Africa; secondly, this took place sometime between 3000,000 to 200,000 years ago; and thirdly, all non-Africans possess limited genetic input from close evolutionary relatives like Neanderthals as a result of sapiens groups encountering and interbreeding with them after leaving Africa.
What we do not know, however, is where within Africa our species evolved. Did this occur in one small area or across a larger one? Or is it a mistake to consider any individual region, with speciation instead proceeding among far-flung groups whose mobility and interaction maintained genetic bonds strong enough to coevolve across this vast continent? Similarly, the precise timing and pace of our evolution within Africa remain obscure. Whereas the earliest traits characteristic of Homo sapiens emerged 300,000 years ago, the full package was only in place some 100,000 years later. What happened in between? Did a specific climatic, cognitive, demographic, or other event (or feedback mechanism) trigger a sudden change? Or was this simply the gradual crystallization of long-term evolutionary trends? Are these changes reflected in the archaeological record, and if so, how?
This project aims to address such questions by taking advantage of recent improvements in aDNA extraction and amplification that are bringing previously overlooked archaeological materials into play. It will include geoarchaeology and biomolecular specialists who will target and extract aDNA from extant museum-curated archaeological collections from African sites that have yielded objects of personal adornment and archaeological sediments from the Late Pleistocene. Together, these archives can offer unprecedented windows into the genetic ancestries of deep-time populations of Homo sapiens before moments of major population dynamism—and resulting genetic overprinting—at the tail-end of the Pleistocene and again during the spread of food production systems during the Holocene.
Meet the Principal Investigator
Brian Stewart is associate professor of anthropology at the University of Michigan and curator of African archaeology in the Museum of Anthropological Archaeology. His research explores the deep-time selective contexts and biocultural responses that led to the evolution of our species’ adaptive plasticity. His primary focus is the archaeology of hunter-gatherers in southern Africa, where he investigates and compares human engagements with highland and desert environments. He obtained a DPhil (2008) and MSt (2001) from the University of Oxford, after earning a BA from the University of Vermont (2000). He was also a postdoctoral research fellow at the University of Cambridge (2008–2012) and a College Fellow at Harvard University (2012–2013). His publications include a sole-authored book, two edited volumes, and articles in venues such as Nature Human Behaviour, PNAS, Antiquity, and many others.
