In 1997, MacPhee and Marx speculated that a rapid spread of hypervirulent disease might explain the die-offs that occurred after the appearance of humans worldwide, including Madagascar. Finally, in 1999, David Burney proposed that the complete set of human impacts worked together, in some cases along with natural climate change, and very slowly (i.e., on a time scale of centuries to millennia) brought about the demise of the giant subfossil lemurs and other recently extinct endemic wildlife. Since all extinct lemurs were larger than the ones that currently survive, and the remaining large forests still support large populations of smaller lemurs, large size appears to have conveyed some distinct disadvantages. Large-bodied animals require larger habitats in order to maintain viable populations, and are most strongly impacted by habitat loss and fragmentation. Large folivores typically have slower reproductive rates, live in smaller groups, and have low dispersal rates (vagility), making them especially vulnerable to habitat loss, hunting pressure, and possibly disease. Large, slow-moving animals are often easier to hunt and provide a larger amount of food than smaller prey. Leaf-eating, large-bodied slow climbers, and semiterrestrial seed predators and omnivores disappeared completely, suggesting an extinction pattern based on habitat use. Since the subfossil bones of extinct lemurs have been found alongside the remains of highly arboreal living lemur species, we know that much of Madagascar had been covered in forest prior to the arrival of humans; the forest coverage of the high plateau region has been debated. Humbert and other botanists suggested that the central plateau had once been blanketed in forest, later to be destroyed by fire for use by humans. Recent paleoenvironmental studies by Burney have shown that the grasslands of that region have fluctuated over the course of millennia and were not entirely created by humans. Similarly, the role humans played in the aridification of the south and southwest has been questioned, since natural drying of the climate started before human arrival. The marshes of the region (in which subfossil remains have been found) have dried up, subfossil sites have yielded a host of arboreal lemurs, and site names, such as Ankilitelo ('place of three or tamarind trees') suggest a recent wetter past. Pollen studies have shown that the aridification process began nearly 3,000 years ago, and peaked 1,000 years prior to the time of the extinctions. No extinctions occurred prior to the arrival of humans, and the recent