Figures & data
Table I. Year one (2000) and year two (2002) mean baseline and unusual event levels of cortisol for each individual chimpanzee. Raw cortisol/ creatinine values (pmol/mg) are presented in column one, but in order to account for the diurnal pattern of cortisol secretion, residual cortisol levels (obtained by using the regression of cortisol on time of collection) were used in the analyses. Sample sizes are listed in parentheses. Blank cells indicate that no samples were collected from the individual for that event; an asterisk next to a name indicates the animal was sampled in both years. The dagger symbol (†) indicates a condition that was significantly different from baseline.
Figure 1 Residual cortisol values for statistical analysis were calculated using the regression of urinary cortisol level (pmol/mg Cr) on time of collection (h). The two years (a, 2000 and b, 2002) were regressed separately to control for between-year differences in baseline cortisol.
Table II. Rates of all social behavior, aggression, and agonism in LJ's group (n=9) in the enrichment condition compared to the baseline condition.
Table III. Rates of all social behavior, aggression, and agonism, as well as aggression and agonism directed toward individuals in the bottom-half of the hierarchy, in Mickey's group (N=9 before change, N=11 after change) in the group change and baseline conditions.