Dr. Pat McGovern, a biomolecular archeologist at the University of Pennsylvania Museum of Archaeology and Anthropology, in Philadelphia, is standing before some large and inscrutable scientific equipment on the museum’s fifth floor as he explains his process to me. “We always start with infrared spectrometry,” he says. “That gives us an idea of what organic materials are preserved.” From there, it’s on to tandem liquid chromatography–mass spectrometry, sometimes coupled with ion cyclotron resonance, and solid-phase micro-extraction gas chromatography–mass spectrometry.
The end result? A beer recipe.
Starting with a few porous clay shards or tiny bits of resin-like residue from a bronze cup, McGovern is able to determine what some ancient Norseman or Etruscan or Shang dynast was drinking as he kicked back thousands of years ago. From a cardboard box, McGovern pulls out several plastic bags containing ancient pottery shards from China. It was from these that he identified the world’s oldest known fermented beverage, dating to about 7000 B.C.—a few centuries after humans began transitioning from hunter-gatherers to farmers. From another box, he pulls out shards and residues collected from four Scandinavian settlements, dating to between 1200 B.C. and 200 A.D. All of them contained traces of an essentially identical beverage, suggesting a drink—McGovern dubbed it “Nordic grog”—that was popular across Scandinavia for more than a millennium.