Using archaeological data of two human intestinal parasites from seventeenth- to early twentieth-century contexts, we explore the intersection of biological and cultural variables that shaped the ecology of cities in northeastern North America during the modern period. These parasites are useful because they require a developmental period in the soil, thus providing a link between human activities and changing environments. Prior to the last decades of the eighteenth century, Trichuris eggs dominate the archaeoparasitological assemblage. Around 1800, there is a shift to increasing proportions of Ascaris eggs, which appears to be largely complete by 1850—a period of increasing urbanization in the northeast United States. Both environmental and behavioral factors play a role in this shift and include the relationship between parasite biology and changing microenvironments, attempts to deal with waste, and use of urban spaces. During this period, poorer households would likely have been at greater risk of parasites because of the ways they used yard spaces, their delayed access to sanitary technology, and the changing nature of urban vegetation in densely occupied neighborhoods.

Archaeological evidence of the ancestral Huron-Wendat Nation of Southern Ontario, Canada, shows a population increase from the thirteenth through sixteenth centuries, suggesting high fertility. Birth timing and infant survival are influenced by mothers' decisions about weaning. This study explores trophic enrichment of δ15N in horizontal dentine slices from 35 deciduous molars (n = 33 dm1, n = 2 dm2) and 39 permanent first molars (M1) representing five Huron-Wendat ossuaries, dating from the fourteenth through seventeenth centuries. Weaning was normally incomplete at the end of dm formation, at an age of about 2.5 years. Post-weaning dentine values appear by the end of crown formation of M1. The weaning process began between 8 and 18 months and was complete in all cases by 3.5 years. Timing of the weaning process does not support the idea that Huron-Wendat population increase was associated with early weaning of infants. Communities from the sixteenth century and thereafter show earlier completion of weaning. Reasons for earlier cessation of breastfeeding may be found in the social and biological disruptions of the era of European contact. Values from permanent teeth of mandibles with sex attributed suggest a more homogeneous, possibly venison-oriented, post-weaning diet among males.