Geoffrey S. Hope and Simon G. Haberle
natural fires. Eucalyptus savannah, like that around Port Moresby today, was probably more extensive all along the southern coast.
New Guinea has a curious fauna which included several large mammal species at the time that people first arrived (Flannery et al. 2002). The island lacks some families of marsupials found in Australia but has a rich rodent fauna. Mammalian predators are almost lacking, their niche being filled by pythons and large birds of prey. Several cave and swamp sites are known (Flannery 1995; Menzies & Ballard 1994) from the central highlands of the island which contain bones of extinct taxa, principally species of large kangaroos (Protemnodon spp.) and diprotodontids (for example Hulitherium, Zygomaturus and Maokopia). These are poorly dated but occur around 35,000 years or older, suggesting that they may have been contemporary with humans. For example a calf-sized diprotodontid, Maokopia ronaldii has been recovered from Kwiyawagi in central Irian Jaya where it seems to have been adapted to extensive subalpine grasslands. It lived until perhaps 30,000 years ago, but no association of its remains with human artefacts has been found. However fire is apparent from around 33,000 years ago in the Baliem Valley, the same catchment as the fossils (Hope 1998). The subalpine fauna seems to have disappeared well before the climate warmed after 14,000 years BP at which time forest limits rose and the mountain grasslands diminished. Hence some other cause (which may include human hunting or disturbance) must be involved.
A more direct case for human interaction is known from Nombe Cave in the Simbu of Papua New Guinea (Flannery et al. 1983). Here extinct fauna occurs in the horizons just preceding human artefacts. The altitude of Nombe makes it likely that it was forested, hence hunting may have been a more gradual process than in open country. Humans have also been responsible for introducing biota to islands in the Pleistocene and subsequently. An example is the Northern Common Cuscus (Phalanger orientalis) which arrived in New Ireland about 20,000 years ago (Heinsohn 2001).
Human hearths up to 30,000 years old are known from the Baliem, the Wahgi peatlands and Kosipe Mission (Hope 1998). Some sedimentary sequences, for example peat beds at Tari and Lake Hordorli in the Cyclops Mountains, record no fires at all over tens of millennia in the Pleistocene. In such places the appearance of charcoal is probably an indicator of human activity (Haberle et al. 2001). The pollen record from the Tari Basin is the only record that shows a continuous sequence from before 28,000 BP through to the present (Haberle 1998). The study shows that, prior to 21,000 BP, forests dominated by Nothofagus, Castanopsis, and Myrtaceae covered the basin floor. Just before the onset of the last glacial maximum at around 21,000 BP we find the first evidence for burning that created a mosaic of grassland and forest. Although there is no direct archaeological evidence for humans in the basin at this time, the rapid increase in burning and opening up of the vegetation is unprecedented in earlier glacial records from the basin and is therefore considered to be a consequence of the arrival of humans in the region. This is at least 10,000 years later than the charcoal records from the Baliem and Kosipe and archaeological sites at Chuave. It may represent a later occupation of the wetter sites.