1. In Sumatra, E. Dubois found 3,170 orang-utan teeth in the Lida Air, Sibrambang and Jambu caves on the Padang highlands in 1889 (Von Koeningswald, 1979); in Borneo, T. Harrisson discovered 111 orang-utan teeth in the Niah cave complex in eastern central Sarawak (Hooyer, 1960); in Java, both Dubois and Von Koeningswald found orang-utan teeth, the former at Trinil, the latter at Gunung Kidul (W. Java) and Sangiran (C. Java), all in lower and middle Pleistocene deposits.
2. Payne (1988) noted that ‘several aspects of the distribution of orang-utans point to the likelihood of a relationship with the distribution of minerals’ his empirical findings, however, do not support this hypothesis. The present survey also yielded no indications that mineral deficiency was important enough to be taken into account.
3. During the present surveys these two populations were found to be extinct.
4. It is not surprising that these early data correspond with the type localities of museum specimens collected between 1780 and 1941 throughout the lowlands of Bomeo; data were kindly provided by M. Jose Braga of Bordeaux University (France) in 1995.
5. According to Payne (1988) this record is supposedly an error; one should, however, not discredit too readily the observation of a respected naturalist, because it is certainly not improbable that orang-utans are able to reach such altitudes during day trips, in particular when much sought-after strangling-figs (e.g. Ficus deltoidea var. kinabaluensis) and a wealth of oaks (Lithocarpus, Castanopsis, Trigonobalanus spp.) and berries (Rubus spp.) occur in the 1,000–2,500 m zone (Comer, 1978; Cockbum, 1978) on mount Kinabalu.