We synthesised evidence on biological correlates of psychological stress in hospital-based healthcare professionals, and examined whether there was evidence of consistent biological changes. Electronic databases were searched for empirical studies; 16 articles (0.6%) met the inclusion criteria. Evidence of a relationship between indices of psychological stress and biological parameters was limited and inconsistent. There was some evidence of a consistent relationship between natural killer cells and lymphocyte subpopulations. Considerable heterogeneity in the methods used was seen. Future prospective studies examining the relationship between indices of psychological stress and natural killer cells, including lymphocyte subsets, is required.
Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amount and timing of animal activity varied widely. Under higher human activity, mammals were less active in undeveloped areas but unexpectedly more active in developed areas while exhibiting greater nocturnality. Carnivores were most sensitive, showing the strongest decreases in activity and greatest increases in nocturnality. Wildlife managers must consider how habituation and uneven sensitivity across species may cause fundamental differences in human-wildlife interactions along gradients of human influence.