North American raccoons are widespread across the contiguous United States and live in close proximity to humans (i.e. urban) and in rural environments. This makes them an excellent species for comparative work on the effects of human environments on phenotypic traits. We use raccoons as a mammalian model system to test whether exposure to human environments triggers a trait of the domestication syndrome. Our data suggests that urban environments produce reductions in snout length, which are consistent with the domestication syndrome phenotype. These results are crucial for the discussion of the validity of the Neural Crest Domestication Syndrome hypothesis. They also offer new opportunities to potentially observe early-stage domestication patterns in a yet non-domesticated mammalian species, without the possibility of introgression or hybridization with other already domesticated mammals.

An updated and extended meta-analysis confirms that the central estimate of the social cost of carbon is around $200–250/tC ($700–900/tCO2) with a large, right-skewed uncertainty and trending up as e...