Technological Change and Population Growth

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The relationship between population growth and technological change has been debated since the end of the eighteenth century–a debate whose main configuration has proved remarkably persistent. During the ensuing 200 years, historically unprecedented rates of change have been observed in both variables: in industrial, commercial, and communications revolutions spreading out from Europe, North America, and Japan; in parallel (though spatially and temporally uneven) revolutions in the technological base of agricultural production; and in a demographic transition–in which mortality decreased and fertility first increased, then decreased–that is still underway in many developing countries. Interconnections there must be, yet the attribution of primacy and direction of causation among these variables, not to mention the nature of the mechanisms involved and means of influencing outcomes in the interest of meeting social goals, remain controversial. Meanwhile, a new awareness of the emergence of complex social-environmental systems, whether at local or global levels, has extended the debate beyond the discipline of economics, and broadened its emphasis from the welfare of the human race to that of the planet.

Malthus: Limits and Closed Systems

Two grand theories dominate the macro-demographic debate, differing on whether technological change is regarded as originating from within (endogenous) or outside (exogenous) the system in question. Proponents of "neo-Malthusian" views, following T. R. Malthus's Second Essay of 1803 and its subsequent revisions, emphasize the biophysical limits to resources (whether renewable or nonrenewable), in a system that is essentially closed. Technological advances, which are introduced to the system by autonomous invention, can increase productivity, thus buying time for growing populations, but they serve to stimulate further growth. Continued growth entails eventual diminishing returns to labor or capital and scarcities in food or other commodities. As the prevailing technology determines the "carrying capacity" of natural resources, in Malthus's own time it seemed natural to point to the famous "checks" which, by increasing mortality, brought the population back into equilibrium. In the world of the early twenty-first century, the environmental agenda interposes scenarios of the destruction or degradation of natural resources between predicted population growth and an eventual Malthusian outcome. Indeed, the threat of mass mortality has receded in a post-Cold War world in which boundless confidence in the potential of induced technological change, and a capacity to ship food and other necessities in large quantities from surplus to deficit regions, have shifted the geographical reference from local or national to global.

Technological change holds out the promise of rising global income levels, following the example of the developed world. Yet it also brings potential threats–two in particular. On the one hand, it is seen as having facilitated population growth in poor societies to ultimately insupportable levels (as in Ireland in the mid-nineteenth century), and on the other, it has generated demands, especially in richer societies, for an unsustainable exploitation of nature, with effects that may be global (e.g., atmospheric warming). It is far from obvious that the economic benefits of urban-industrialism can eventually be extended to the world's poor. Led by writers such as Paul and Anne Ehrlich and Lester Brown, a powerful constituency emerged in support of population limitation in countries with high fertility. To reflect the multivariate nature of the environmental threat, Ehrlich and Holdren in 1974 invented the I=PAT formulation (Impact of an economic system on the environment = Population × Affluence × Technology). However, although its simplicity has recommended it to many researchers and policy makers, the complex interdependencies and dynamics among P, A, and T render it unsuitable as a model of complex systems.

Boserup: Technological Change and Agricultural Growth

A view of technological change as endogenous is often associated with the economist Ester Boserup (1910–1999), who explored the implications of this assumption for agricultural growth. Such views see necessity as the mother of invention and the uptake of technology as a process driven by changing factor proportions, in particular (in the agricultural case) those between labor and land. As scarcity drives up the value of land, and of agricultural and other outputs, investments in higher productivity become possible, first as additional labor per hectare (by increasing the frequency of cultivation or the intensity of weeding and fertilizing) and then, as increasing population densities generate markets and urban concentration, in the form of investments in land improvements. At low population densities, laborsaving investments best respond to poor farmers' factor ratios; but as densities increase, land-saving investments become necessary. Adoption of known technologies (whether indigenous or imported) is the key process, though Boserup acknowledged that demographically-driven demand can also play a role in spurring new inventions. An analysis of the technological history of agriculture and its relations with the growth of dense and secure populations, cities, and commerce, suggests "a quantitative relationship between an area's population density and its predominating food supply system" (Boserup 1981, p. 15). However, a growing density is a necessary, but not a sufficient, condition for labor-intensive agricultural growth. This is reflected in the technological diversity among contemporary farming systems in developing countries.

The economist Julian Simon (1932–1998) took this argument further. National data from many countries–rich and poor, North and South–suggested a correlation between indicators of population size and growth on the one hand and technical innovation and cultural creativity on the other. Inventive potential is considered to be randomly distributed in a population (equity, education, interaction, and other variables being equal). "Hence the net result of an additional person is an increase in the total number of new ideas" (Simon 1986, p. 377). Taking a strong stance on the potential of technology to extend the effective size of resource inventories, to enable recycling, and if necessary to substitute for scarce resources, Simon argued against the advocates of population limitation. "Population growth spurs the adoption of existing technology as well as the invention of new technology" (Simon 1996, p. 376).

There is indeed an accumulation of knowledge about historical achievements in food and agriculture that calls into question models and scenarios predicting imminent scarcity or ecological collapse such as those found in The Limits to Growth (Meadows et al., 1972). FAO data show that in the 1990s, developing countries were increasing cereal output by 1.5 to 2.2 percent yearly on a cultivated area-per-person that had declined from 0.18 ha in 1960 to 0.10 ha in 1995. However, investing in technology requires economic incentives, as shown by the history of the green revolution in Asia or improved corn yields in Africa. An urban-industrial sector may be essential to motivate surplus production and offer a stream of new technologies, which in turn provide a route to high-productivity agriculture and promote the structural transformation needed in countries having abundant rural labor.

African Case Studies

A case study from Kenya illuminates these relationships. In the Machakos and Makueni Districts of Kenya, decades of rapid population growth, massive losses of natural capital through soil erosion and deforestation, and high food insecurity appeared to justify a Malthusian perspective–which was in fact embraced by the government and its advisers. However, closer investigation reveals a revolution in land conservation and economic productivity since the 1930s, favoring instead a broadly Boserupian process of change. In the 1930s wealth was channeled into livestock as the most readily marketable commodity the farming families in these districts could produce. Between 1930 and 1990, against a background of a sixfold increase in population and a massive transfer of land from common grazing land and woodland to permanent, privately owned farmland, the value of agricultural output per head increased nearly fourfold and its value per hectare more than eleven-fold. Keys to this achievement were changes in the profitability, sources, and technological priorities of private investment. Aggressive (even coercive) promotion of soil conservation measures by the government during the 1940s and 1950s produced a minor "Machakos miracle" of landscape transformation, which did not survive for long after independence (1962). The real "miracle" occurred later, beginning in the 1970s, when farmers in the long-settled and very densely populated hills recognized that conservation terraces improved crop yields (through their beneficial effects on soil moisture) and embarked energetically on private investment in terracing.

Further incentives for investment derived from improved access to markets (especially the coffee market, previously restricted to European producers), a loosening of restrictions on selling corn out-side the district, and above all the rapid growth of urban demand for fruit and horticultural crops, which progressively opened up new agricultural options. Farmers could draw on a growing bank of technological knowledge from both government and private sources. The agrarian transformation extended even to the driest areas, although the inhabitants of those areas were acutely aware of their constrained farming opportunities (due to drought, risks to animal health, and high cost of access to markets) and were more dependent on diversifying their incomes through education and migration. The social distribution of the benefits of this transformation were far from equitable and farmers continued to face significant economic and ecological risks. However, in broad terms a Boserupian framework appears to offer a valid explanation of the outcomes of long-term interaction between the growth of population and of technology.

The Boserupian model originally reflected Asian rather than African experience. The vigor of debate on the African cases (of which there are many; see Turner et al., 1993) reflects both the rapidity of economic and ecological change under rapid rates of population growth (fertility has only recently begun to decline in Africa) and the severity of environmental degradation as perceived by some international agencies. As the African drylands have a low agroecological potential, high risk of drought, and high rates of population growth, they pose the sharpest challenges to adaptive technology. Yet the possibility of a transition from more extensive (land-using) technologies, which are unsustainable under conditions of population growth, to more intensive (labor-using)–and sustainable–ones, even where the supply of capital is severely constrained by poverty, is suggested by a variety of African evidence. In Kano in Nigeria, on-farm population densities of over 220/km2 have evolved on a time-scale of centuries, supported by a system of fertilized annual cultivation, and in symbiosis with major urban product and labor markets. In Maradi in Niger a build-up of population through rapid in-migration, with extensive deforestation for farming, collided with the drought cycles of the 1970s and 1980s to threaten a collapse in productivity in a classic Malthusian crisis. But subsequently, there is evidence that a mix of market forces, project interventions, and indigenous investments have halted and in places begun to reverse this trajectory. Grain production per head has been maintained, in part through additional labor and investment.

A Synthesis

An opposition between a view of population (Malthus) or technology (Boserup) as the dependent variable has not discouraged some analysts–including Pryor and Maurer (1982), Lee (1986), and Simon (1992)–from suggesting that a theoretical synthesis is possible. Simon proposed a single integrative model of technological change in which Malthusian "innovation-pull" and Boserupian "population-push" hypotheses coexist. The real world has also moved on: just as no closed Malthusian systems exist at the local or national level in the early twenty-first century, so Boserup's open system is finally closed at the global scale.

At its core, Malthusian theory posits an equilibrium between population and resources. Many environmentalists seek to control or reverse what they see as maladaptive departures from that equilibrium. However, some ecologists challenge this view of nature, seeing in many ecosystems evidence of variability, irreversibility, crisis, and surprise. A Boserupian frame of reference appears better suited to a dynamic and nonlinear view of social-environmental systems as it contains implicit provision for such concepts as thresholds, transitions, creative changes between states, and resilience under stress. Analysis of the complex interactions among populations, technologies, and environments should not be constrained in advance by modeling assumptions.

See also: Boserup, Ester; Carrying Capacity; Energy and Population; Limits to Growth; Natural Resources and Population; Simon, Julian L.; Sustainable Development.


Boserup, Ester. 1965. The Conditions of Agricultural Growth. London: Allen and Unwin.

——. 1981. Population and Technology. Chicago: University of Chicago Press.

Ehrlich, Paul R., and Anne H. Ehrlich. 1970. Population, Resources and Environment: Issues in Human Ecology. New York: W. H. Freeman.

Ehrlich, Paul R., and J. Holdren. 1974. "The Impact of Population Growth." Science 171: 1212–1217.

Gunderson, L. H., C. S. Holling, and S. S. Light. 1995. Barriers and Bridges to the Renewal of Ecosystems and Institutions. New York: Columbia University Press.

Kasperson, J. X., R. E. Kasperson, and B. L. Turner II, eds. 1995. Regions at Risk: Comparison of Threatened Environments. Tokyo: United Nations University Press.

Lee, Ronald D. 1986. "Malthus and Boserup: A Dynamic Synthesis." In The State of Population Theory: Forward from Malthus, eds. D. Coleman, and R. Schofield. Oxford: Basil Blackwell.

Meadows, Donella et al. 1972. The Limits to Growth: A Report for the Club of Rome. New York: Picador.

Mortimore, Michael. 1998. Roots in the African Dust: Sustaining the Sub-Saharan Drylands. Cambridge, Eng.: Cambridge University Press.

Rosenberg, Nathan, and L. E. Birdzell Jr. 1987. How the West Grew Rich: The Economic Transformation of the Industrial World. New York: Perseus Books.

Simon, Julian L. 1986. Theory of Population and Economic Growth. New York: Blackwell.

——. 1992. Population and Development in Poor Countries. New Haven, CT: Princeton University Press.

——. 1996. The Ultimate Resource 2. Princeton, NJ: Princeton University Press.

Tiffen, M., and Michael Mortimore. 1994. "Malthus Controverted." World Development 22: 997–1,010.

Tiffen, M., Michael Mortimore, and F. Gichuki. 1994. More People, Less Erosion: Environmental Recovery in Kenya. Chichester, Eng.: John Wiley.

Tomich, T. P., P. Kilby, and B. F. Johnson. 1995. Transforming Agrarian Economies: Opportunties Seized, Opportunities Missed. Ithaca, NY: Cornell University Press.

Turner, B. L. II, G. Hyden, and R. W. Kates. 1993. Population Growth and Agricultural Change in Africa. Gainesville: University Press of Florida.

Michael Mortimore

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Technological Change and Population Growth

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