Updated 11:12 a.m. Sept. 18
At-home DNA testing is everywhere.
In a matter of years, the nascent technology has emerged as a potent — and sometimes controversial — criminalistics tool. It’s also unearthed troves of family secrets and dropped more than a few “genetic bombshells” on users.
Now, the commercialization of this technology is making a much broader revelation possible — one involving the arc of human history and set an hour south of Pittsburgh.
At Meadowcroft Rockshelter in Avella, researchers gathered recently to collect soil samples that will be analyzed for genetic information — skin flakes, droppings, and more — potentially left behind by birds, animals, and nomadic humans some 19,000 years ago.
The results of this testing could improve our understanding of the site’s cultural and scientific significance. They could also give us a previously unglimpsed picture of what life was like at the “oldest site of human habitation in North America.”
And all of this was made possible by the falling prices and rising accuracy that have accompanied the free market rise of (partly) DIY DNA.
In an effort to better understand the stakes here, we reached out to the researchers involved: Archaeologist Devlin Gandy and Meadowcroft’s newly appointed Director of Archaeology, James M. Adovasio, whose books and one-on-one tours of the site continue to captivate audiences.
We asked them about how modern technology is forming our understanding of the ancient world, what they hope to see come of this testing, how this information could help address Meadowcroft’s critics, and more.
The conversation has been edited for clarity and length.
Q: The Meadowcroft site was discovered decades ago. Why is this testing only being done for the first time now?
Devlin Gandy: Using it for archeology is very new. It’s really only in the last five years that we’ve kind of started to reanalyze archeological sites by looking for DNA left in the sediment, and of course that DNA comes from the organisms that were alive in these places.
Q: How does that work?
Devlin Gandy: It could come from birds flying into caves and defecating. It could come from people coming in there and having a meal or people just scratching their heads and leaving skin flakes which DNA binds to the soil. Or it could come from plant pollen flying into cave or from a basket that’s left there and rots away until there’s nothing left of it.
Q: So this type of testing is relatively new in this application?
Devlin Gandy: Environmental DNA is a field of genetic research, and while it was first made a possibility in 2004, it has really undergone a renaissance in the last five years because the technology has gotten so much better and the costs of doing genetic work have dropped dramatically.
Q: How dramatically?
Devlin Gandy: Basically we can do things that 10 years ago would have cost hundreds of thousands of dollars for just a thousand dollars now. So the technology has really changed in that respect.
Q: How did it become so much cheaper?
23 and Me, basically. Like, the future is in genetics, so all the processes and all the different aspects of it have gotten cheaper.
And you now have the ability to do a lot with very little material, as long as the preservation is there. And that’s the question — we don’t know what the preservation is at Meadowcroft.
Q: What do you expect/ hope to find through this testing?
Devlin Gandy: This site never had environmental DNA testing done before, and I’m doing this as an exploratory measure to see what the genetic information potentially is at this site. At the moment we’re keeping an open mind until we know what the conditions of the soil are. The best-case scenario is that we find a phenomenal preservation of genetic material and greatly expand our knowledge of the site. At worst, we might just add to what we already know but not have it be anything mind-blowing.
Q: When you say “greatly expand our knowledge,” what exactly do you mean?
Devlin Gandy: Information that would allow us to reconstruct the prehistoric environment and see if there’s animals that we maybe don’t have bones of here, plants we don’t have the pollen of. We can also try to understand some of the bacteria and fungi we may not be able to see otherwise. And, of course, there’s the potential for a human presence as well. Of course, there’s no guarantee with any of this.
(A press release about the project says the discovery of human DNA at Meadowcroft could help identify the origin of the humans who used the site thousands of years ago, giving us a better understanding of how North America was populated.)
Q: So you’re trying to get a better sense of what the ecosystem looked like back then?
Devlin Gandy: Yes. There’s been criticism of the site over the years simply because there isn’t a very clear record of ancient plant and animal remains here. So this is one way to see if they might be present. And the other way, for very early layers, is to see if we have a cultural presence and human presence as well.
Q: Who’s funding this testing?
Devlin Gandy: This is part of my PhD work. I’m a PhD candidate at the University of Cambridge, and I’m part of Eske Willerslz’s lab. (Willerslz is considered the founder of the field of environmental DNA.)
So the processing of these samples will take place at his center, the Center for Geogenetics, in Copenhagen. I will be transporting these samples there myself. I just flew out for this and am going right back.
Q: What do the samples look like?
Devlin Gandy: They’re basically plastic centrifuge vials (containing soil taken from different layers and depths of the Meadowcroft site).
Q: Doctor Adovasio, you were the first researcher to lay eyes on the site and unearth some of the artifacts contained there. What’s the emotional significance of this testing for you personally?
James Adovasio: The participants of this enterprise never thought initially that we were going to find anything very old. We always wanted the excavation to be a methodological tour de force, which means that every time something new, whether it’s a piece of hardware or a new analytical tool, comes on the scene, we would try to incorporate it into our repertoire of research activities. So when this opportunity presented itself and Devlin made himself available, we naturally jumped at it because it shows you archeology is never static and should never be static; it needs to, as field, constantly reinvent itself so that the kinds of questions we ask of the past can be answered better than we could do it yesterday.
But emotionally we’re very pleased that even if the results of this testing are negative, we’ve had the opportunity of doing this.
Q: … in the interest of being as thorough as possible and never resting on your laurels?
James Adovasio: Exactly.
Q: Unrelatedly, I was at the site with my family recently, and a piece had fallen from the rockshelter roof days earlier, puncturing the protective overhang. That left me wondering, what are the risks of weather and even climate change on this site long term?
James Adovasio: If you were here a couple weeks ago then you saw the current structure and realized that if a large enough part of the roof detached for whatever reason, climate change or whatever, it will go through that (protective overhang) like an eggshell. We have done our best to stabilize sections of the roof that seem most prone to detachment, but somewhere down the line there will be a major block detachment from that roof. Hopefully not for centuries.
Dave Scofield, director, Meadowcroft Rockshelter and Historic Village: We have an expert who checks the cliff face regularly and earlier this year we installed anchors in the rock and cable netting over a particular rock. That rock wasn’t moving, but we thought we should be conservative about it.
Q: How will you publicize your findings from this DNA testing?
Devlin Gandy: We just don’t know yet. We aim for a peer-reviewed journal, of course, but don’t know what we’re going to find — and what we find is really going to dictate how we do the media for that.
Q: What’s the timetable?
Devlin Gandy: The samples are collected but testing of the material will last three to six months.
Q: Could the results alter or rewrite our understanding of what life was like at Meadowcroft millennia ago?
Devlin Gandy: This will enhance our understanding of what life was like then and at this site, but I see it as more complementary. The site already had so much great work done. I hope I can fill in some blanks and add more info to it, but we just don’t know yet. There’s still a lot of uncertainty in archeology. I think archeology is that quest just to know about the past, however fleeting.
Update: This article has been updated to reflect a new estimate for the earliest known uses of the Meadowcroft Rockshelter by prehistoric people. Experts now believe the site served as a campground for early nomads going back at least 19,000 years.