The evolution of extinction risk: past and present anthropogenic impacts on the primate communities of Madagascar.

There are two possible approaches to understanding natural and human-induced changes in the primate communities of Madagascar. One is to begin with present-day and recent historic interactions and work backwards. A second is to begin with paleoecological records of Malagasy primate communities before and immediately following human arrival, and the associated evidence of human and nonhuman primate interactions, and work forwards. On the basis of biological and climatic studies, as well as historic and ethnohistoric records, we are beginning to understand the abiotic and biotic characteristics of Madagascar's habitats, the lemurs' ecological adaptations to these unique habitats, the extent of forest loss, fragmentation and hunting, and the differential vulnerability of extant lemur species to these pressures. On the basis of integrated paleoecological, archaeological and paleontological research, we have begun to construct a detailed chronology for late prehistoric Madagascar. We are beginning to understand the complex sequence of events that led to one of the most dramatic recent megafaunal extinction/extirpation events. Combining the perspectives of the past and the present, we see a complex set of interactions affecting an initially rich but vulnerable fauna. The total evidence refutes any simple, unicausal (e.g. hunting/habitat destruction/climate change) explanation of megafaunal extinctions, yet unequivocally supports a major role--both direct and indirect--for humans as the trigger of the extinction process. It also supports a change over time in the relative importance of hunting versus habitat loss, and in the trophic characteristics of the primate communities in Madagascar.