http://www.sciencemag.org/news/2021/08/antibiotic-resistance-has-spread-deep-dark-forest-bear-teeth-reveal

Sweden’s brown bears nearly disappeared in the early 1900s, the victims of enthusiastic trophy hunters and angry farmers. Conservation efforts have slowly brought them back—along with an unexpected bonus. DNA from the animals’ teeth now reveals that, almost immediately after antibiotics were introduced in the 1950s, the drugs had penetrated even the remotest Swedish forests. The new finding, out today, could help scientists better understand the spread of antibiotic resistance, a worldwide problem with major impacts on human health.

“[This study] is a really nice example of how one can use ancient DNA for real-world problems,” says James Fellows Yates, an archaeogeneticist at the Max Planck Institute for the Study of Human History who was not involved with the research.