The following figure is adapted from a paper by Cohen, Kaplan, Cunnick, Manuck, and Rabin (1992), which examined the immune response of nonhuman primates raised in stable and unstable social groups. In each group, animals were classed as high or low in affiliation, measured by the amount of time they spent in close physical proximity to other animals.

Higher scores on the immunity measure represent greater immunity to disease. How would you interpret these results?