Behavior of Infant Chimpanzees During the Night in the First 4 Months of Life: Smiling and Suckling in Relation to Behavioral State

This article reports the behavior of 3 newborn chimpanzees in the first 4 months of life, reared by their mothers and living in a community of 14 chimpanzees in a semi‐natural enriched environment. We focused on spontaneous activity during the night partly because sleeping behavior constitutes an essential part of the infants' activity. Observation during the night also had the advantage of keeping the influence of the mothers' activity as well as the environmental stimulation constant throughout the observation period. We report several interesting findings. Behavioral states defined through overt features such as open or closed eyes were variable during the night, with the rapid eye movement (REM) and non‐REM sleep patterns alternating much as they do in human infants. Although crying is one of the distinctive behavioral states in the case of human infants, the chimpanzee infants did not cry like humans. Suckling behavior was often accompanied by open eyes until the end of the first 2 months. Thereafter, suckling with the eyes closed became more prominent. Although there were no explicit stimuli, the newborns showed neonatal smiling with the eyes closed during REM sleep periods. However, neonatal smiling disappeared within the first 2 months and was replaced by social smiling with open eyes. Taken together, the results suggest a strong similarity between human infants and chimpanzee infants in terms of developmental changes in spontaneous activities at around 2 months of age.     

WHEN DO SHELTER‐IN‐PLACE ORDERS FIGHT COVID‐19 BEST? POLICY HETEROGENEITY ACROSS STATES AND ADOPTION TIME

This study explores the impact of Shelter‐in‐Place Orders (SIPOs) on health, with attention to heterogeneity in their impacts. First, using daily state‐level social distancing data, we document that adoption of a SIPO was associated with a 9%–10% increase in the rate at which state residents remained in their homes full‐time. Using daily state‐level coronavirus case data, we find that approximately 3 weeks following the adoption of a SIPO, cumulative COVID‐19 cases fell by approximately 53.5%. However, this average effect masks important heterogeneity across states‐early adopters and high population density states appear to reap larger benefits from their SIPOs. (JEL H75, I12, I18)