Delayed Dispersal in Humans: Natal Territory Quality and Dispersal Timing

Elizabeth Blum, Birmingham-Southern College

In humans and numerous avian species, unlike most animals, dispersal from the natal family may not coincide with reproductive maturity. Combining longitudinal human population data with life history theory, this research tests explanations for this anomaly. Emlen (1995) suggested parallels between humans and birds with regard to the circumstances that influence dispersal timing; previous work applied Emlen’s model to humans using proxy measures of “Natal Territory Quality” (NTQ). Here, using two age-based cohorts from the PSID, direct measures of NTQ are extracted to more rigorously test Emlen’s prediction that higher NTQ leads to later dispersal. Specifically, this study investigates whether economic variables describing family of origin (NTQ) and local conditions influence age at three dispersal events. The various NTQ measures appear to have different influences on the three dispersal events, suggesting differential salience of NTQ components for each type of dispersal. Results also point to discrepancies across the two cohorts.