Overview
- Researchers reported in Nature this week that DNA from Yersinia pestis was recovered from teeth at four cemeteries near Lake Baikal, appearing in 18 of 42 sampled individuals.
- Genetic and radiocarbon evidence indicate at least two separate Mesolithic outbreaks, the earlier one about 5,500 years ago and a second one several centuries later.
- The ancient strains carried virulence factors but lacked the flea‑adaptation gene ymt, which led the team to infer droplet (respiratory) human‑to‑human spread rather than classic flea‑borne transmission.
- Burial patterns and age data show unusually high mortality among children and close kin groups, suggesting rapid family‑level transmission during the outbreaks.
- The finding pushes back the timeline for deadly plague in Eurasia, points to marmots as likely animal reservoirs, and challenges the idea that large epidemics required settled farming communities.