TheAlexKnapp writes: Different groundwater supplies in different geographic regions often have different oxygen isotope ratios. Archaeologists have been using this fact to help track migration patterns in ancient cultures by examining oxygen isotope ratios found in human bones. But there may be a catch to this — namely, humans don't only drink water. They often drank alcohol instead. Anthropology students at Wagner college brewed chicha de maíz, an ancient Peruivan corn beer, and discovered that its oxygen isotope ratios are different from the water it was brewed with. Since ancient Peruvians drank a LOT of chicha, archaeologists need to properly consider this consumption when they're trying to reconstruct migrations..