so true of many other tribal groups.
The indigenous socio-economic system: Is it sustainable?
While asserting the ability of many threatened peoples to adapt, and stressing the resilience of their traditional economic systems in handling many external influences, it still has to be asked whether the traditional system by itself can, in the light of continued pressure from outside as well as from within the society, provide tribal groups with a sustainable future. While indigenous skills could be an appropriate starting point for trying to improve technologies suitable for tribal societies, there is also evidence which suggests that not all indigenous resource-use practices are ecologically and environmentally sound. Increased population pressure on land resources, increased dependency on a commercial economy, and demand for cash incomes have brought about environmentally destructive changes in native resource-use patterns.
This is most evident in one of the principal traditional agricultural systems- swidden agriculture, which is frequently portrayed in modern environmental literature as ecologically sound. While it was indeed so in the past, all evidence in South-East Asia suggests that population density is a key variable in the sustainability of the swidden system (Cramb, 1978; Dove, 1981; Spencer, 1966). The maintenance of an adequate long fallow period-the critical basis for sustainability-depends on a sufficiently low man-land ratio. But in South-East Asia, even in the sparsely populated island of Borneo, there are only a few regions, especially agriculturally suitable areas, where such a situation still prevails. In other words, the assumption of socio-economic and environmental equilibrium in tribal societies is gradually becoming a misplaced notion. Economically, this is partly exemplified by changing land-use patterns, especially the pattern of a mixture of subsistence and commercial agriculture in place of swidden, which by the early 1990s characterizes the rural cultural landscape of large parts of South-East Asia.
This is still more true of economies with minimal involvement in agriculture, and reliance principally on wild or semi-sown food sources, and on the hunting and fishing of wildlife. A low population density is an essential part of the environment of such a system. The whole problem will therefore be illustrated here with reference to the situation observed among one of the now more famous tribal communities in South-East Asia-the Penan of Sarawak, who, as claimed in much recent writing (for example, Hong, 1987; INSAN, 1989; Sahabat Alam Malaysia, 1990), are still practicing an economic system which is ecologically in balance with the environment. It is proposed, especially by many environmentalists, that the best way to ensure a sustainable future for the Penan is to maintain their traditional way of life as a nomadic tribe.
The penan and the timber blockade
The Penan have attracted global attention since 1987 through their blockade of timber roads. In general, however, outsiders' perceptions of the Penan tend to differ from the actual situation. Despite all the changes that have occurred, most current descriptions of the Penan still tend to follow the ethnographic models: an isolated society hitherto unaffected by or not interested in interacting with the outside world; self-sufficient and contented with their traditional way of life even to the extent that they are not interested in any worldly possessions from the outside. While these notions may fit some pre-1960 Penan communities, it is no longer the case in over 90 per cent of the current Penan societies concerned. There is no doubt, of course, that the Penan everywhere in Borneo are economically the most backward.
In 1987, the Penan embarked on large-scale blockade of timber roads in the Baram district of Sarawak, one of the main logging areas in the state. A number of reasons have been put forward to explain the blockade. Prominent among these is the destabilization of the traditional economic systems of the Penan, principally the destructi