Epigenetic correlates of neonatal contact in humans.

Animal models of early postnatal mother-infant interactions have highlighted the importance of tactile contact for biobehavioral outcomes via the modification of DNA methylation (DNAm). The role of normative variation in contact in early human development has yet to be explored. In an effort to translate the animal work on tactile contact to humans, we applied a naturalistic daily diary strategy to assess the link between maternal contact with infants and epigenetic signatures in children 4-5 years later, with respect to multiple levels of child-level factors, including genetic variation and infant distress. We first investigated DNAm at four candidate genes: the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), µ-opioid receptor M1 (OPRM1) and oxytocin receptor (OXTR; related to the neurobiology of social bonds), and brain-derived neurotrophic factor (BDNF; involved in postnatal plasticity). Although no candidate gene DNAm sites significantly associated with early postnatal contact, when we next examined DNAm across the genome, differentially methylated regions were identified between high and low contact groups. Using a different application of epigenomic information, we also quantified epigenetic age, and report that for infants who received low contact from caregivers, greater infant distress was associated with younger epigenetic age. These results suggested that early postnatal contact has lasting associations with child biology.

The heights of French-Canadian convicts, 1780s-1820s.

This paper uses a novel dataset of heights collected from the records of the Quebec City prison between 1813 and 1847 to survey the French-Canadian population of Quebec-which was then known either as Lower Canada or Canada East. Using a birth-cohort approach with 10year birth cohorts from the 1780s to the 1820s, we find that French-Canadian prisoners grew shorter over the period. Through the whole sample period, they were short compared to Americans. However, French-Canadians were taller either than their cousins in France or the inhabitants of Latin America (except Argentinians). In addition to extending anthropometric data in Canada to the 1780s, we are able to extend comparisons between the Old and New Worlds as well as comparisons between North America and Latin America. We highlight the key structural economic changes and shocks and discuss their possible impact on the anthropometric data.