Adult male positioning in baboon progressions: order and chaos revisited.

Abstract

Evidence of nonrandom positioning among adult males is crucial for a protection theory of the spatial organization of baboon progressions. In a recent study it was suggested that systematic positioning of troop members other than mothers and infants is so slight and rare that progressions may be regarded as essentially random. This suggestion depends upon debatable methodological points presumably downgrading previous findings of nonrandom order. Reanalysis of data from this study revealed numerous analytical and statistical problems, as well as serious calculation and other errors, and showed that the findings are consistent with results of the present and previous research. Adult males tended toward the front or back of progressions, a tendency which was intensified in potentially dangerous situations. Dominant males were disproportionately more often frontward and subordinate males rearward. Nonrandom order, which was found for a variety of circumstances at high levels of statistical significance, was unusually general in that it occurred in 6 studies, 7 troops, 2 species, and 5 locations. Such generality is consistent with a protection theory postulating phylogenetic underpinnings of a sociospatial organization which allows an advanced primate to adapt to terrestrial coexistence with predators.