I have always assumed that world population level and rate of increase are a major problem. I recently read more widely on the subject (e.g. Nicholas Eberstadt, in The True State of the Planet, The Free Press, 1995), and as a result I have somewhat modified my opinion. The world has coped well with explosive population growth this century. Nevertheless, the capacity of social systems to absorb the huge increase in numbers should not lull us into overoptimistic expectations that the world can continue to handle ongoing unregulated increase in population.
In 1798 the Rev Thomas Malthus argued that humanity tends to reproduce much faster than food supplies can increase. Therefore, a portion of humanity must always be condemned to starvation. The thinking of environmentalists has been dominated by the Malthusian principle. They warned that sharply increasing populations this century would quickly use up limited world resources, resulting in dire consequences. In his 1968 book, The Population Bomb, Paul Erlich warned that hundreds of millions of people would starve to death by the 1970s. This dire prediction never came to pass. The reasoning of Malthus applies much more closely to animal populations than to humans.
World population has more than tripled since 1900, rising from 1.6 billion in 1900 to 5.3 billion in 1990, an average annual growth rate of about 1.3 per cent. The pace of growth has not been steady, peaking in the 1960s at about 2 per cent a year. It is now about 1.6 per cent a year. Today the annual rate of growth in more `developed' regions is about 0.4 per cent; the annual rate in the `less developed' regions is about 1.9 per cent. Within less developed regions distinct differences are also clear. Africa's annual rate of increase is about 2.8 per cent, while the average rates of Asia and Latin America are about 1.7 per cent.
In 1950 North America and Europe contained about 28 per cent of world population. In 1990 this share was down to 19 per cent. This is quite a change from previous centuries. During the Ages of Exploration and Colonisation, European populations grew much more rapidly than non-European populations. Global life expectancy has increased this century from 30 to 64 years. Global infant mortality has fallen from 170 deaths per 1,000 births in 1950 to 60 in 1990. Rapid population growth has occurred mainly because people have stopped dying so readily and not because they have started breeding like rabbits.
In fact, fertility rates have been declining in Europe since the end of the 18th century and in most developed countries today birth rates are well below population replacement rate. Populations in East/Western Asia, the Caribbean and Latin America have also shown declining fertility rates since the early post-war era.
Total fertility rate (TFR) is the average number of births per woman. TFR for the world as a whole dropped between 1950 and 1995 from about 5 to 3.1. In the more developed countries, TFR dropped from 2.8 to 1.7. In the less developed regions TFR dropped from 6.2 to 3.5. TFR values differ markedly among low income countries. In 1950 the TFR in Africa was about 6.5. By the early 1990s it had only declined to 5.8.
As world population boomed per capita world food production increased markedly and per-capita food availability has risen in every major region. Global per capita calorie availability rose by 30per cent between 1930 and the late 1980s. For the less developed regions of Africa, Asia and Latin American as a whole, per capita food supplies rose by about 40per cent. Sub-Saharan Africa performed well until the early 1960s but increased little thereafter. Per-capita productivity world wide has increased markedly along with the population boom. Between 1950 and 1990 per capita gross domestic product tripled in the developed world, doubled in India, Pakistan and Latin America, increased six fold in Asia (including a nine fold increase in Japan), and increased by 30 per cent in Africa (South African figures not included).
On the negative side, there have been several famines this century, prolonged periods of economic downturn, and a generally weak performance in sub-Saharan Africa. Can these problems be explained in terms of population pressures overwhelming limited resources? There were three major famines this century and each claimed several million lives: the Soviet famine of 1934, the Bengal famine of 1943, and the China famine of 1958-1961. African famines have also caused hundreds of thousands of deaths. Over-population was not the primary cause of any of these problems. For example, the Chinese famine followed Mao's collectivisation campaign that destroyed the agricultural system.
Sub-Saharan Africa's poor performance followed decolonisation which occurred between the late 1950s and the early 1970s. The history of native governments has been troubled. Civil strife and ethnic tensions have been common, not infrequently erupting into tribal warfare. Traditions of accountability and the rule of law have been eroded. Widespread primary education often suffered. In the light of such impediments it seems entirely unnecessary to invoke over-population to primarily explain Africa's poor agricultural and economic performance.
To recap, over the past century surging global population growth has been accompanied by improved standards of health, wealth and longevity. Nevertheless, I believe it would be wise to limit population growth at this stage. The improvements over the last century have occurred in spite of increased world population, not because of the increase. So far, human ingenuity has kept us "ahead of the game". But there are down sides to having too many people.
The greater the number of people, the greater the amount of energy that must be expended to service their needs. This causes environmental damage. We can see this in the form of the enhanced greenhouse effect, acid rain, etc. Overcrowding is also polluting and stressful in itself. Imagine how awful it would be if there was no longer such a thing as an open road, or a lonely place. And finally, Malthus underestimated mans ability to adapt to changing conditions, but, even for humans, there must be a Malthusian limit. I see no advantage in discovering where that limit lies.
William Reville is senior lecturer in biochemistry at UCC