NESTS, TREE HOLES, AND THE EVOLUTION OF PRIMATE LIFE-HISTORIES

In contrast to the majority of primates, many prosimians, some New Wor ld monkeys, and the great apes rest in tree holes or self-constructed nests during their inactive periods. The goal of this comparative stud y was to examine possible functions of this interspecific variation. I nformation on resting behavior, maternal behavior, and basic life-hist ory traits was gleaned from the literature and mapped onto a phylogene tic tree of primates for various comparative tests. Parsimony-based re constructions revealed that only the use of nests or tree holes as she lters for young infants can be unequivocally reconstructed for various higher taxa, suggesting that it is functionally different from the us e of shelters by adults (who may be accompanied by infants). Further r econstructions revealed that the ancestral primate was most likely noc turnal and solitary and produced a single infant that was initially le ft in a shelter and later carried orally to a parking place in the veg etation-a combination of traits exhibited by many living galagos. Evol utionary losses of the use of nests were concentrated among diurnal an d nonsolitary taxa and weakly associated with evolutionary increases i n body size. Thus, protective functions of nests or tree holes used by prosimians are either secondary or there are alternative ways of obta ining protection. Because the evolution of larger litters was signific antly associated with the presence of shelters, the presence of relati vely altricial young among prosimians best explains the use of nests a nd tree holes, which are in most but not all cases also used by adults . These shelters therefore play an integral part in the life-history s trategies of primitive primates and their ancestors and evolved second arily among anthropoids for other purposes. (C) 1998 Wiley-Liss, Inc.