Effects of intergroup conflict anticipation and participation on log-transformed urinary oxytocin levels in wild chimpanzees of East group (n = 67 samples, 7 subjects, 29 events). Shown are medians (thin horizontal lines), quartiles (boxes), percentiles (2.5 and 97.5%; vertical lines), minimum and maximum (laying crosses), as well as the fitted model and its 95% confidence intervals (thick lines).