The question of when humans first entered the Americas is enormously exciting and contentious for the simple reason that it is so consequential. History begins in the Western Hemisphere with the first human footfall in Alaska. The late Francois Bordes famously observed that that this epochal benchmark in human history would not be matched “until man lands on a hospitable planet belonging to another star.” And, of course, the consequences of finding that metaphorical footprint are not limited to its implications for science and history. There are social and political implications as well. Some American Indians regard the very idea of fixing a date for the original discovery of the Americas as a threat to their status as indigenous peoples. If it can be shown that their ancestors arrived here only 13,000 or even 20,000 years ago, they worry that their moral and legal claims to the New World would be undermined and they could be considered as just another immigrant group. Because the answer to this question is so consequential, it’s important that we neither accept a claim for a very early site that is not well substantiated nor reject a claim simply because it doesn’t fit our expectations. To some extent, the answer to the question of when people first came to America is constrained by the genetic histories of North and South American Indians. The genetic variability documented so far suggests strongly that the ancestors of all living Indians left Asia no earlier than about 17,000 years ago. Of course this doesn’t mean that there could not have been earlier arrivals. It just means that if there were people here much earlier they did not contribute to the genetic legacy of modern American Indians. This could mean they came in insufficient numbers to thrive and so went extinct before the ancestors of modern groups arrived. But if someday we establish that humans were here prior to 17,000 years ago, we will need to explain why there is no indication of their presence in the genetic signal. In my September column in the Columbus Dispatch, I discuss the recent claim that the South American site of Vale da Pedra Furada might be 20,000 years old. This site is not the same as the related site of Pedra Furada, which was evaluated by the archaeologists David Meltzer, James Adovasio and Tom Dillehay back in 1994. Many of the same issues, however, are central to the debate over the meaning of Vale da Pedra Furada. The so-called artifacts may be naturally broken quartz cobbles that only happen to look like human-made tools and the early radiocarbon dates may not relate to the human occupation of the site. The problem of how to tell the difference between artifacts and “geofacts” — naturally broken rocks that only resemble artifacts, is more complicated than you might think. It’s made even more complicated by the fact that Tom Dillehay found that people at the 14,600-year-old site of Monte Verde in southern Chile appear to have used naturally broken rocks as tools. Dillehay and his team were able to identify them as tools only because they had been hafted to wooden handles and the wood was preserved along with the stones. The search for the earliest site in the Americas is a bit like hunting for a snark. How will we ever know when we’ve found it? If you find a site that turns out to be older than any previously documented, how can you know that there isn’t an even older one out there somewhere waiting to be found? It’s also possible that older sites were here, but over the millennia have been destroyed by glaciers, floods, farming, surface mining, or looting. In Ohio, we don’t have much evidence for sites older than the widely accepted 13,000-year-old Clovis culture though we have lots of Clovis points. There are artifacts made from Ohio’s Flint Ridge flint in the deepest levels at Meadowcroft Rockshelter, which tell us that people at least passed through here earlier than Clovis. A leg bone from a giant ground sloth found in a Huron County wetland bears evidence that the animal was butchered by Paleoindians around 13,700-years-ago. Brian Redmond of the Cleveland Museum of Natural History and several colleagues have identified a number of cutmarks on the bone made by the stone knives of either very early Clovis or pre-Clovis people. We’ll keep looking for older sites, because the search is fun and it matters. And while we may never find the oldest site in Ohio, or America, it’s virtually certain that we’ll find sites older than anything we’ve found so far. Who knows, maybe even a site more than 20,000 years old! But, as in any science, such an extraordinary claim, which appears to defy our expectations, will need to be supported by convincing data and thoughtful arguments. Brad Lepper For further reading Boeda, Eric, et al. 2014 A new late Pleistocene archaeological sequence in South America: the Vale da Pedra Furada (Piaui, Brazil). Antiquity 88:927-941. Dillehay, Tom 2014 Standards and expectations. Antiquity 88:941-942. McConaughy, Mark 2004 Meadowcroft Rockshelter. National Historic Landmark nomination, National Park Service. Redmond, Brian G., H. Grebory McDonald, Haskel J. Greenfield and Matthew L. Burr 2012 New evidence for Late Pleistocene human exploitation of Jefferson’s Ground Sloth (Megalonyx jeffersonii) from northern Ohio, USA. World Archaeology 44:75-101.