Robert Attenborough is a senior lecturer in biological anthropology, at the School of Archaeology and Anthropology, Australian National University, Canberra. His principal interests are in health, nutrition, population and ecology, with principal field experience in Papua New Guinea and the Himalayas. He has co-edited Human Biology in Papua New Guinea (Clarendon Press, 1992) and Papuan Pasts (Crawford Press, in press). A recent publication on population is his contribution to Human Population Dynamics (ed. H. Macbeth & P. Collinson, Cambridge University Press, 2002).

Population and resources: some hurdles for empirical research
by Robert Attenborough

Session 6: Questions/discussion

As a human biologist – or, as I would more often say, a biological anthropologist – I have struggled in trying to articulate or synthesise a view from my discipline on population and environment. There are several reasons for this, including the smallness of the discipline, especially in Australia; and perhaps more troublingly, the fact that – to be blunt – most of us in our daily work do not address the issue. Indeed, it seems to me that the work at a local level, which most nearly approaches such issues, was more prevalent in the 1970s than it is now – as was interest in the wider, macro debates of a ‘limits to growth’ nature. I am having, therefore, to be a bit speculative in piecing together some fragments of what I think my colleagues and I might say.

The population-environment relationship is multi-dimensional and impacts flow both ways. Amongst other things on which there is not time to focus, environments hold resources, both renewable and otherwise, to which human populations look in order to satisfy their needs and desires. To a human biologist the most obvious of these resources are food and water. In the bare fact of depending on such resources, human populations resemble those of other mammals. But there’s the rub. Animal population ecology is a complex and sometimes contentious discipline, but it is one discipline and there’s fair consensus amongst its practitioners as to the issues and the analytical approaches. If we were here to discuss moths or frogs, or kangaroos or chimpanzees, we might differ as to our estimates of carrying capacity, or whether density-dependent or density-independent factors were more powerful; but I don’t think we’d be having something we’d call a ‘population-environment debate’. So what is distinctive about humans, or about human population ecology?

Part of the answer to that, surely, emerges when we try to imagine studying the population ecology of one particular local human population and community, as if we were animal ecologists working on a particular forest, lake or island. Even the thought experiment is sufficient to show the horrendous number of empirical measurements required.

More than that, it immediately raises the question: which human society? Whereas we may be likely to take one population of white-winged choughs, for example, to stand for others, it matters very much which human society we choose for study. They vary hugely in their ways of making a living out of an environment, even if it’s the same environment – most hunter-gatherers famously living at especially low population density, for example. This renders problematic any attempt to define a fixed carrying capacity for humans in a particular environment. It is always possible that, differently organised in social or economic terms, a community in a given environment might have a different – though of course never infinite – carrying capacity.

Such a thought experiment in local human population ecology also shows that the dynamics of the system – the interplay between, say, local population numbers and local food abundance – are not fully captured, because, wherever you draw a line around a population, food and other material resources will cross it, often on a large scale. Thus many of the interesting things are elusive: they happen off stage (Thomas 1976 example). The capacity of human communities to use social exchange systems to reach for resources beyond their local environments is, especially nowadays, scarcely at all impeded by geographical barriers or by distance, though very much impeded by poverty.

The conclusion must be, not that there is no population-environment dynamic in the human case, but that peculiarly human complications make it hard to see. One response to this challenge – you may think it a somewhat romantic response – has been to make this dynamic visible by looking for it in out-of-the-way places: closed mountain valleys, small remote islands, and clusters of rainforest hamlets. In such places one may, if one is an optimist, hope that people and resources mainly stay within the local ecosystem; feedback loops are short, local and fast-acting; traditional ways of life may promote population homeostasis; and ecological variables are on a limited scale, amenable to measurement.

(Click on image for a larger version)

Useful points can emerge from the study of such cases. For example, there is no guarantee of an eventual population-resource equilibrium. Homeostasis can fail, as it apparently did for the Henderson Islanders in Polynesia who, from the archaeological evidence, seem to have brought about the extinction of six bird species and then disappeared themselves. A more complex case, but one of survival, is that of the Hawaiian archipelago. By an ingenious method based on the density of radiocarbon-dated materials, Dye & Komori (1992) have drawn a graph of pre-censal population growth, calibrated by the first credible census in the 1830s. If we accept the method, the result appears to document slow growth from the 4th century AD, faster growth from the 12th to the 15th century, and then fluctuation without net growth to the 19th century. An ecologist might read into this the arrival of a first human population in a vacant, productive and healthy environment, the population of that environment, and eventually the encounter with density-dependent brakes on population growth as the new niche fills up. While there are other possible interpretations, and faunal extinctions along with social, political and agricultural changes are part of the picture, Hawaii does nonetheless look like a reasonable candidate for successful population homeostasis over several centuries.

(Click on image for a larger version)

(Click on image for a larger version)

However, as a study, the Hawaiian case is unusual. And there are limits on what can be learnt from the human population ecology of small remote places. I have already hinted at some of the reasons. Another is the observer effect whereby outsiders tend to contribute to the transformation of what they have come to study. One of the most credible censuses of any hunter-gatherer population was undertaken in 1929 amongst the Tiwi people of Bathurst and Melville islands; but by the time of their next census, their way of life had been substantially changed – and one census is a slender basis for a population ecology.

Insights into human population ecology – also limited but nonetheless useful – may also come from a perhaps less expected source, that of historical demography. At least there we may sometimes obtain long runs of data. The most substantial data come from Europe and China, from 1 AD to the present (Heilig 1999: International Institute for Applied Systems Analysis). In neither area are annual population growth rates, calculated as averages for each century or so, further from zero than 0.4 per cent, until 1700 AD: often they are considerably closer to 0 than that. While these growth figures exceed the 0.015 per cent calculated for the whole human population from 100K years ago to the present, they are not huge figures. It has been argued (Wilson and Airey 1999) that, far from showing us human populations up against a series of dramatic Malthusian crises, these figures show us low growth and a significant measure of population homeostasis over the greater part of recorded human history. The demographic mechanisms and the ecological background are hard to link in, but the proposition of population homeostasis relative to environmental resources is there on the table, and it’s not without supporting evidence, at least for pre-industrial populations. Of course the counter-proposition is also argued.

(Click on image for a larger version)

For pre-industrial populations, too, we now have some sophisticated theory, due to writers such as Lee (1986) and Wood (1998), which brings Malthus together with other theorists, notably Boserup. Wood develops concepts which he calls ‘individual well-being’ and ‘demographic saturation’, with a ratchet model of population growth and economic intensification. From this some striking propositions emerge. To quote him a little,

population regulation may indeed be common in the preindustrial world...it rests upon the ultimate inability of individuals and economies to overcome the inherent finitude of resources. …regulation is something imposed on the population, not an evolved feature of it. …It is hard to believe…that preindustrial populations routinely adopt behaviours to ensure the long-term sustainability of resources. …population growth can lead to economic stagnation and its attendant population pressure but also …that pressure can induce further economic change and a temporary amelioration of conditions for the average individual. …preindustrial populations are not expected to evolve spontaneously to a state in which they are well buffered against environmental perturbations.

Wood does not extend his uncomfortable model to industrial populations, and I shall not presume to do so for him.

Just as with local studies, so also with macro, national and global studies of the ‘Limits to Growth’ type, my impression is that these attract less attention amongst my disciplinary colleagues than they did in the 1970s. I think this is partly because of their huge difficulties as empirical research exercises. In some respects at least they subsequently proved wrong or at least too simple in what they said about population growth, food shortage, depletion of non-renewable resources, and environmental pollution with toxicological consequences. The long-term population growth future now looks somewhat more moderate, with population ageing counter-balancing growth as an issue. The food issue is partly one of distribution, organisation and technology. And so on. This is not to say that my colleagues think everything is fine on these fronts. But I don’t detect big new initiatives to tackle them holistically. Perhaps the newer worries are attracting more of that kind of attention from them: these include global warming, and for Australia in particular, water.

Environments, as the topics just raised illustrate, are more than merely resource banks, even if we look at them purely materialistically and anthropocentrically. I must mention one further aspect, even if with Frank Fenner and Tony McMichael here I don’t need to make much of it. That is the bearing of the environment, including human society itself, on human health. To some extent that has already been implicit: density-dependent regulation of human numbers may sometimes mean excess mortality including from infection, malnutrition or a combination. Frank, as some will know, has written amongst other things on the different disease patterns – infections, injuries and so forth – associated with different ways of life – especially with different population sizes and densities, patterns of sedentism or nomadism, and close associations with other animal species and their pathogens. Populations that are small enough and isolated enough are much less vulnerable than large cosmopolitan ones to certain airborne infections, for as long as that state lasts. Malaria too, still a large-scale killer, has been considered greatly aggravated by the advent of agriculture and sedentism. Some now believe that the origins of HIV should be sought in the growth of the bush meat trade, associated with human population growth in central Africa: it need not be the only such infection.

And there I am on the brink of another important point: the implications of human population growth for the survival of other species and the biodiversity around us. But I had better not open that.

We have been encouraged to express personal views. It will be apparent that I think the project of human population ecology, even viewed as pure research, is an immensely difficult one. I think it is difficult in any setting, and especially so in a complex modern industrialised and globalised economy like Australia’s. And it is made no less difficult by the hope of basing policy, including sustainable development, on them. Such an acknowledgement of the hurdles ahead is surely part of the process of surmounting them. I think that this conference is entirely right to include serious dialogue between members of different disciplines as amongst the things that could help us in these efforts.

My own feeling – to go out on a limb, and I promise that I was planning to say this before I heard yesterday’s mention of boundary-patrolling – is that the role of economics is a particularly crucial one. This is not solely because of its historical character as a discipline, but also because in its very subject matter it holds the key, or seems to, to what I described a few minutes ago as 'the capacity of human communities to use social exchange systems to reach for resources beyond their local environments'. I would like to close with a short quotation from the distinguished anthropologist Roy Rappaport. I don’t know whether economists, including ecological economists, would accept his comments as fair; but as a confessed non-expert I do think they capture something of the frustrations of non-economists. Writing about a certain approach which he called monetisation, he wrote (1993):

Monetisation…forces the great range of unique and distinct materials and processes that together sustain or even constitute life into an arbitrary and specious equivalence. Phenomena that relate to each other essentially in terms of their qualitative distinctiveness are represented and understood in terms of a logic that reduces all qualitative distinctions to mere quantitative differences, a logic that, as it were, attempts to 'bottom line' the world. This logic is especially destructive of ecological systems. …The criticism here is not of all uses of monetary metrics or all forms of economic analysis but of their privileged status.

For a revitalisation of research and debate in this area, and indeed for sustainable development, I think we need an approach which goes beyond monetisation in this sense: I don’t claim to know what it is.