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Palynological studies throughout Madagascar have demonstrated the importance of Quaternary climate variation and fire ecology in determining the character of prehuman vegetation in Madagascar. Although rain forest may have persisted along the eastern escarpment throughout the Cenozoic, dynamic shifts have occurred in other areas, forcing the biota of dry woodland, grassland, montane, and semi-desert regions to accommodate changes in temperature, precipitation, and seasonality. Some highland and western regions were influenced by drought and fire long before any known human inputs, and this is reflected in plant and animal adaptations and ranges. The probable effect of burning by humans has been to increase fire frequency and to spread pyrogenic communities into areas previously too wet or too dry to ordinarily support a natural fire regime. The emerging synthesis regarding presettlement vegetation and subsequent human-caused changes helps clarify some of the formerly puzzling aspects of species distributions.