Long-term effects of infant attachment organization on adult behavior and health in nursery-reared, captive chimpanzees (Pan troglodytes)

This research traces the long-term effects on health, well-being, personality, and behavior of adult chimpanzees as a function of their attachment to a primary human caregiver assessed when they were 1 year of age (van IJzendoorn, Bard, Bakermans-Kranenburg & Ivan, 2009). Of the 46 chimpanzees assessed at 1 year of age, we assessed health in 43 individuals, adult behavior in 20 individuals, and adult well-being and personality in 21 individuals. Attachment disorganization was found to be a significant predictor of stereotypic rocking in adult chimpanzees (F(1,18) = 7.50, p = .013). For those subjects (N = 24) with a full 20 years (birth through age 20) of health data available, both rearing experience and disorganized attachment were found to be significant predictors of upper respiratory infection frequency (F(2,21) = 8.86, p = .002).  Chimpanzees with disorganized attachment exhibited average subjective well-being as adults, whereas chimpanzees with organized strategies exhibited higher than average subjective well-being as adults. These results support the findings of human attachment research and are in line with attachment-based predictions for chimpanzees, such that the consequences of an early history of disorganized attachment may be adverse and long lasting.