Climate change, society, and pandemic disease in Roman Italy between 200 BCE and 600 CE.

Records of past societies confronted with natural climate change can illuminate social responses to environmental stress and environment-disease connections, especially when locally constrained high-temporal resolution paleoclimate reconstructions are available. We present a temperature and precipitation reconstruction for ~200 BCE to ~600 CE, from a southern Italian marine sedimentary archive-the first high-resolution (~3 years) climate record from the heartland of the Roman Empire, stretching from the so-called Roman Climate Optimum to the Late Antique Little Ice Age. We document phases of instability and cooling from ~100 CE onward but more notably after ~130 CE. Pronounced cold phases between ~160 to 180 CE, ~245 to 275 CE, and after ~530 CE associate with pandemic disease, suggesting that climate stress interacted with social and biological variables. The importance of environment-disease dynamics in past civilizations underscores the need to incorporate health in risk assessments of climate change.

Measles virus and rinderpest virus divergence dated to the sixth century BCE.

Many infectious diseases are thought to have emerged in humans after the Neolithic revolution. Although it is broadly accepted that this also applies to measles, the exact date of emergence for this disease is controversial. We sequenced the genome of a 1912 measles virus and used selection-aware molecular clock modeling to determine the divergence date of measles virus and rinderpest virus. This divergence date represents the earliest possible date for the establishment of measles in human populations. Our analyses show that the measles virus potentially arose as early as the sixth century BCE, possibly coinciding with the rise of large cities.