TRANSACTIONSOF THE ROYAL SOCIETYOFTROPICAL MEDICINEAND HYGIENE (1993) 87, SUPPLEMENT 1,13-18 s1113

Economic implications of demographic change

R. H. Cassen International Development Centre, Queen Elizabeth House, University of Oxford, 21 St Giles’s Street, Oxford, OX1 3LA, UK

Abstract This paper considers the principal economic arguments surrounding the fact of rapid population growth in developing societies. It suggests that the extent of controversy which has attended this topic in the past can be greatly reduced by identifying precisely the indicators in respect of which the economic effects of population growth are judged. If indicators of individual well-being are chosen, the effects are likely to be negative in most cases. For other indicators the outcomes are less clear. The paper also examines some of the principal national and global issues affected by population growth, and suggests that it is not population alone, but the relations between population and income growth and technological and policy choices, which have to be understood if the ‘population problem’ is to be seen in true perspective. Prospective population growth can be accommodated; but institutional and political capacities will be severely tested by it, and could prove inadequate. Most countries, and the world as a whole, would certainly be better off if population were to grow more slowly.

Introduction It is well known that Thomas Robert Malthus pro-

duced the first dynamic economic-demographic model, though his 18th century English would never have en- compassed such a barbarous term. It is also well known that his model’s main assumptions and predictions have proved false. Agriculture, on a global basis, has grown faster than population for a very long time, far from being doomed to lag behind it as Malthus thought. And populations in most countries have slowed their rates of growth with rising living standards, rather than been re- strained by ‘positive checks’ when population presses against the means of subsistence.

It is less well known that by the end of his life Malthus was no longer a Malthusian; in the last (1826) edition of the Essay on Population (the first was in 1798), he advo- cated universal education as a counter to the ‘population principle’; it would help to postpone marriage and limit population growth, giving to the ordinary man ‘a portion of that knowledge and foresight which so much facilitates this object in the more educated part of the community’.

This is a glimpse of the historical background to the modern understanding of the demographic transition. Relations between population growth and economic de- velopment are two-way’. Increases in population affect both the volume and composition of output; and, as economic development takes place, a wide variety of changes occurs which in turn influence both mortality and fertility. There is a period during which population growth is relatively rapid, while mortality declines before fertility responds both to that decline and to other forms of social change--especially the spread of education; and then fertility begins its decline. Neither Malthus’s orig- inal views, nor modern models of ‘immiserising growth’, or ‘low-level equilibrium traps’, have any significant cur- rency among economists today.2

In what follows, I seek significant generalizations, largely abstracting from major differences across and within countries. In almost everything to do with devel- opment, exceptions can usually be found to any proposi-

’ This is essentially why there is no (negative) correlation between population growth and economic growth. Some authors, e.g. SIMON (1989), use this fact to counter the common view, that population growth has harmful effects on the economy; but there is a simultaneity bias in the correlations--see BLANCHET (1991).

2 This would include ‘demographic traps’ of the kind suggested by KING (1990). One fundamental flaw in that argument lies in the fact that the sooner mortality declines, the sooner fertility is likely to follow, and the lower will be the ultimate population size. Infant and child mortality declines appear to be a necessary, though not a sufficient, condition for fertility decline in poor, high fertility countries. It is unlikely to be a good strategy (not to speak of ethical issues) to postpone mortalitv decline deliberatelv. (This is not to say that there cannot 6e low-level dynamic equilibria; there can be, and at least locally, there have been. But they are not inescapable.)

tion. In a half-hour lecture on an enormous topic, one cannot hope to do more than capture some general tend- encies, and contribute to the analysis of issues; the sub- ject is, in any case, a long way from being prone to defi- nite conclusions.

The macroeconomic case Academic discussion of the theory of the effects of

population growth on the developing economy has been full of controversy. Much of it has arisen from a lack of clarity about indicators. One can look at 4 separate ques- tions, in each case implicitly contrasting 2 paths for an economy over time, one with a higher and one with a lower rate of growth of population.

(i) Does rapid population growth reduce the rate ofgrowth of a poor country’s gross national product (GNP)?

The answer to this question is ‘probably not’. Popula- tion is a resource, and unless no use whatsoever can be made of additional numbers, or actual growth-reducing effects occur, it will add to growth.3

(ii) Does rapid population growth reduce the rate of growth of a poor country’s GNP per head?

The answer to this question is ‘very probably yes.’ Population growth may not influence the rate of capital formation positively or negatively-the literature is in- conclusive. But if capital formation is unaffected by population growth, &ere will still be less capital per head. and therefore less income oer head. (The moduc- tivit; of capital should rise with Lore labo& pe; unit of capital, and lower wages.)

Essentially, economists ask whether there is anything in population growth itself which raises labour produc- tivity; the answer seems to be that of course productivity can rise over time, but this is mostly independent of population growth; if anything (see question iv) rapid population growth makes it harder to raise productivity. There is one argument which points the other way: larger populations may permit economies of scale-the same combinations of capital and labour produce higher output.4 But this argument too has only limited force.

3 One argument has been the alleged ‘savings effect’-that savings, and therefore investment, would be reduced under high population growth. But this argument is uncertain today. For an early statement of the case, see COALE & HOOVER (1958). For some treatments of the entire debate, see BIRDSALL (1989), CASSEN (1976), MCNICOLL (1984), or KELLEY (1988, and an unpublished paper entitled ‘Revisionism revisited’, presented to World Bank Seminar in Washington, DC, in January 1992. The case is also made that environmental damage is not accounted for in GNP and, if it were, the impact of popuiation on GNP growth would be negative: but the relations between population growth and the environment will be addressed elsewhere in this paper.

4 See footnote on next page

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Economies of scale are available in export markets- countries do not necessarily need extensive markets of their own. Markets are not matters of sheer numbers, but of numbers with incomes to spend, so the argument makes assumptions about the issue it claims to address. Further, the argument has not normally encompassed natural resources and the environment as factors of pro- duction. It is at the least begging the question to assume that environmental effects do not create diminishing re- turns to scale. Clearly population cannot grow indefi- nitely without running into diminishing returns---but there are two questions: if there is a phase of higher re- turns to scale, what happens during the transition to- wards it? It could well be that the transition brings ef- fects which worsen the economy’s capacity to take advantage of scale economies. And at what point will diminishing returns be encountered? There is little if any empirical analysis of these issues.

(iii) Does population growth increase welfare? This is of course what interests, or should interest, us.

Economists, contrary to some views, are not concerned with incomes, but with happiness. Income per head is obtained by dividing total income by the number of heads; but this assumes that the number of heads is not itself a potential source of satisfaction. Income per head is commonly used as an index of welfare, but in this con- text it begs the question.

In fact, few discussions of our topic ever address this point, for a simple reason: economics has nothing con- clusive to say about it. Suppose we could actually measure individual welfare, in inter-personally com- parable ‘utils’. Is a society of a million individuals enjoy- ing 500 utils each better or worse than one of a million and a half enjoying 450 utils each? Economics cannot answer such a question and, in all probability, nor can anything else. The universal tendency is to consider le- vels of individual welfare, as measured by some index. But it is worth entering the caveat that one does so by ig- noring the issue of whether the existence of more human lives should enter positively or negatively into the cal- culus .

While it is difficult to talk of these things at a societal level, it is more comprehensible at the familial level. One can well imagine parents saying as a matter of deliberate choice ‘it may make us poor, but we want a large fam- ilv’.5 It is nerfectlv natural. and not denied even bv econ- omists, that parents may -value children for their own sake, regardless-up to a point at least-of the effects on their standard of living.

In this context one can refer to the ‘revisionist view’6 which grew up in the 1980s; in one version, it departs from the macroeconomic case, and asks: parents make their decisions, and have a right to do s+why is this a societal issue at all? The answer is, of course, that there may be conflicts between individual choices and the so- cial good: in fact the revisionist view argues that these conflicts have been exaggerated. I shall here bypass this argument; there are major conflicts, in my view-but they should be accurately reflected in the macroeconomic case. The effects, or ‘externalities’ as they are known to economists, that individual parental decisions impose on

4 This argument is due to BOSERUP (1965), much qualified later (BOSERUP, 1981). Most of her work relates to the question of whether increasing rural population density induces favourable technical change. It may well have done over the long sweep of history; but today relevant technology is commonly available, even if not adopted. See further below.

5 This is not of course the tenor of the developing country microeconomics of family formation, most of which assumes that parents take economic considerations into account in fertility decisions, and some of which-correctly or not-concludes that they may be better off with large numbers of children. (It could also be that parents are better off but the children are not: there are many difficult issues of welfare within the family.)

6 The phrase is due, I believe, to BIRDSALL (1989).

other families and society and economy as a whole should broadly be captured in the assessment of the impact of population growth on the economy.

(iv) Does rapid population growth impede the attainment of other developmental goals?

The answer to this question is‘yes’, in virtually every case. Whether the goals are those of human develop- ment-health, education, personal fulfilment of every kind-or sustainable economic growth with rising em- ployment and levels of living, any low income economy has to struggle to provide for growing numbers and can provide more easily and at higher standards for less rapidly growing numbers. The rest of this paper looks at these issues.

Human development Education

All low income countries are far from being able to offer adeauate educational and health facilities for their existing populations. In most countries primary school enrolments at least have grown faster than population for several decades, with some faltering in sub-Saharan Af- rica in recent vears. This reflects the hiah nrioritv most governments have placed on education ‘;s long as econ- omic conditions permit. But the quality of this education is often Door-insufficient nhvsical facilities. text-books and educational materials, few’ levels of teacher training; and there are high drop-out rates. Increasing enrolments and reducing drop-out rates require increasing both the quantity and the quality of provision.

It is obvious that the larger the numbers for whom this has to be done, the harder-it is to attain. A projection for Pakistan shows that, starting in 1990, a 20 year dif- ference in the date of reaching replacement fertility makes a difference of over one-third (7 million children) in the population of primary school age by the year 2010; and over 27% (5.5 million children) in that of secondary school age (WORLD BANK, 1989). Such figures would be typical of a country with a high rate of population growth. Given Pakistan’s already low rates of enrolment and low levels of public expenditure available for educa- tion, this fact by itself implies severe difficulties for the country in achieving economic progress.

Production and competition world-wide are becoming increasingly based on skill and knowledge. Low-income countries, and especially those with modest educational attainments and rapid population growth, will find it dif- ficult either to complete their development or to keep up with the speed of change in the international economy. There is a distinct possibility of a widening of the econ- omic gulf between the better-off and the poorer countries for this reason alone.

Health All developing countries except the most advanced

have huge backlogs of health provision. As with educa- tion. raoid nonulation growth hinders the achievement of universal &&ision and improvements in quality of health services, as societies labour to make modest stand- ards available to growing numbers. In addition, high fer- tility is itself a cause of high mortality-both child and maternal mortality. Pregnancy-related deaths and, espe- cially where contraception is not available, lethal abor- tions, are the leading sources of female mortality in the 15-50 years age-group in very many developing coun- tries. (Risk of death due to pregnancy is 50-200 times more in developing than in industrial countries.) There are numerous other adverse effects on mothers’ and children’s health of large families and close child spacing.

It is not only a matter of health services., of course, but of other health investments, particularly m water supply and sanitation. What needs to be done, or more usually the backlog of what is undone, grows at a pace that ren- ders remedial measures difficult where population num- bers are doubling in a generation; in the poorest coun-

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generate relatively little increase in demand for cereals, and none at all amongst better off people, whose demand is more or less saturated; but there would be shifts in de- mand amongst poorer people whose incomes were ridng from rice to wheat and to coarse grains for animal feed. According to one estimate, total world demand for food grains rises from 2 billion (2x 109) tonnes in 1990 to 3-6 billion in 2030: only O-14 billion is the result of rising in- comes, per caput cereal consumption increasing from 377 to 404 kg: 1.46 billion, or over 90% of the increase in demand, iz the result of- a projected 68% increase in population over the40yearsa.

tries, remedy may be simply out of reach. At best they are duplicating facilities for growing numbers, at the ex- pense of investments which could be making the rest of the economy more productive, or raising quality within the health s.ecfor.

One of the most obvious ways in which family deci- sions affect those outside the family is through the labour market. Each household makes an imperceptible dif- ference; but the combination of all households hoping for income gains from large family size results in a rapidly expanding labour market which will tend to depress pay. Couoled with the effects on education and health orovi- sion; and the calls a growing po ulation spreading the capital stock among arger numbers, in- P

mak& on

stead of raising the amount of capital per worker in the productive sectors, the result is a poorly educated and in- sufficiently healthy labour forcbitself a condition for low productivity-whose numbers drive down pay in an economy which can transform itself only slowly.

This is not a ‘low-level equilibrium trap’; even under such conditions, living standards can rise. Eut the alter- natives are the same when looked at from this point of view: conditions improving only slowly for rapidly rising numbers, or improving faster for a more slowly growing population. It is not only a question of productivity and mcome growth; people deprwed of education and good health cannot avail themselves of much that society has to offer in terms of the quality of life.

Once again one might note that high fertility makes its own contribution to this: a woman experiencing the cur- rent average fertility levels of sub-Saharan Africa will spend approximately one-third of her adult life in preg- nancy or breast-feeding (DASGUFTA, in press). Under high fertility, the burdens of child-rearing on women are particularly heavy. One of the most absurd of the pro- population arguments in the literature is that the more people a society has, the more ‘geniuses’ there will be, and these are the people who create technical and cultu- ral innovation (SIMON, 1981). It is the unfulfilled poten- tial of society undergoing rapid population growth that should concern us, rather than the possibility of such growth generating additional exceptional individuals; how many such individuals may there not already be, whose porcntial gifts are never discovered.

Sustainable economic development The issues discussed above seem relatively uncon-

troversial to me. Much more difficult are the uestions of the implications of rapid population growth 7 or the sus- tainabiliry of economic development, and indeed of life on the planet’. The most difficult issue is to isolate the effects of population growth from those of economic growth. In what follows, I shall make the simplifying as- sumption that population growth has no effect on econ- omic growth; economic growth takes place, but its com- position and distribution are affected by population growth, and so are living standards. We can then ask, what effects are attributable to economic growth, and what to population.

Perhaps the 3 most significant effects come through the demand for food; through increasing rural or urban population density; and through poverty. While income growth affects environmental impact, the differences with and without population growth are particularly sig- nificant in these areas. The environmental impacts will be felt particularly on renewable resources: soils, air, water,and plant and animal populations.

FOUd Without population growth, rising incomes would

7 By ‘sustainable’ 1 mean ‘reproducing levels of consum rion withour detriment to the productive capaciry availab e 10 Y future generations’.

One major concern is the potential environmental im- pact of meeting this demand. Naturally much will de- pend on where the additional crops will be grown. But it has to be expected that a great deal of it will have to be grown where the additional demand originates, i.e. in the developing world. Here there is little scope for bringing additional land under cultivation at acceptable economic and environmental cost. (Some 60% of current deforesta- tion in Africa and Latin America may be due to agricul- tural expansion; WORLD BANK, 1992.) Most of the in- crease will thus have to come from improved yields; in any case, while there are environmental problems in in- tensifying agricultural production, they are probably less troublesome than extending low-input agriculture. They are, however, quite troublesome enough.

Assuming no major climate change [and of couzsc glo- bal warming is an uncertain factor), the environmental effects depend mainly on land, water and technology. One study has examined fairly carefully the prospects for achieving output increases on the scale projected. It con- cludes that, OII the basis of existing knowledge, environ- mental damage on a considerable scale is the likely result.

The roles o p"

ce of current land degradation, and the relative human and natural causes, arc among many sig-

nificant unknowns (ANDERSON & CROSSON,, 1991; MYERS, 1988). If agriculrure were to expand by mcreas- ing the area of forest, range and pasture land brought under cultivation, erosion and sedimentation would in- crease; hence the conclusion that intensification is essen- tial. It is well known that considerable damage is curren- rly being done to soils already under cultivation, but it is believed that improved soil conservation practices could limit it (‘could’ is the critical word; one would not predict that such Dractices will necessarilv be widelv followed>. The critical and most intractable*limiting constraint on increasing output under existing technology is water.

The problems arise for a number of reasons. One is the growing economic and environmental costs of extending irrigations; another is the increasing competition of water demand arising from sources other than agriculture- urban and industrial growth; and a third is the ‘extcr- nality’ problem: each farmer's use of water for irrigation imposes costs on downstream users of the same water, through the transmission of salts, agricultural chemicals and sedimentation. It is very difficult to induce farmers, either by incentives or by regulation, to change practices that have no cost to themselves in any way which would limit the cozt to others. Although use of agricultural chemicals in the developing countries is at present mostly at low levels, needs for agricultural intensification are likely to expand their use greatly. For all These reasons, econotic and environmental costs associated with water for agricultural expansion are likely to rise very consider- ably.

The upshot of this analysis is that yield-improvinp technology, and particularly water-saving or dro;ght-rey

6MY calculations, based on WORLD BANK (1992) and ANDERSON & CKOSSON (1991).

9 The potential for improving rhe management of existing irrigation is considerable, and a large proportion of past irritation works alreadv reauires refurbishmenr: but such measures are nor judged-to be- likely to make a large lm~acc an increasing irrigation porenrial relative to rhe magnitude of the needs for increased cropo~tput.

sisting and noxious-chemical-avoiding technology, is going to be essential for raising crop production on a sus- tainable basislo. Such technology has appeared in the past; but that is no guarantee that it will in the futureI]. Many observers believe thar the volume of resources cur- rently being devoted to agricultural research does not come close to meeting the likely needs.

The discussion here has concentrated on cereals, which are of course critical for growing populations in low-income countries. There are naturally problems as- sociated with fish and other food sources. many of which already face threats from growing demand and insuffi- cient regulation. But on rhe whole these threars have arisen mostly through income growth and improvements in catching, preservation and transport technologies. It is true that once incomes reach the point where mosf people can afford fish and animal foods, the more people there are the grearer will be the strains on resources, and the more costs will increase. Increasing population also induces more people to seek Iivelihoods from coastal and fresh-water fishing. But these issues cannot be treated within the scope of the present paper.

This discussion is of course highly relevant to the wider issue of the macroeconomics of population change. Were populations growing more slowly, economies could devote fewer resources to decreasing-return agriculrure and foodproduction,andmoretootherformsof produc- tion which may prove easier to expand on a sustainable basis. 12

Critical questions in the population debate surround the effects of increasing population density. In addition to the food issues discussed above, rural population growth puts pressure on land, plant and forest resources, and wild anti habitats; increasing urban densities or the spread of urban areas also create a host of problems. Once again, one must try to separate the population ef- fects from those of income growth and technological change-though this is exceptionally difficult in the rural scene.

There is a familiar syndrome in many parts of the rural ‘Third World’ of deforestation, soil degradation, declin- ing agricultural productivity, and deteriorating ecology. It has to be said, however, that these phenomena are far from universal. Africa alone exhibits a varietv of exoeri- ence: there are areas where agricultural producnvlty, forest cover and soil conservation have all improved with increasing population density (see, e.g., TIFFEN, 1992). There are also examples of where these things have nor happened; indeed, many parts of Africa could be cited as counter-examples IO the ‘Boserup hypothesis’ of popula- tion-induced improved intensity of cultivation (see foot- note 4 on p. 14). One author contrasts the Boserup view of Lauf~n~m~u~ inrensitication’ with thar of policy-led in- tensificationl3. The favourable factors include positive government policies, market development, education, access to information, technology and capital, and changes in family and community which permit en- hancedrolesforwomen.'~

Unfavourable developments have stemmed most often from shortening fallow periods (which are imposed by in- creasing population density), without adequate attention to conservation and nutrient-maintaining measures. But

“The water problem varies in importance from region to region; but it may prove in many places to be the most immediately limiting constraint on agricultural growrh. By 'technology' here is meant improvements in plant varieties as well as cultivation pracrices.

11 at nitrogen as a constrainr, and the likelihaad of technologicalimprovementa,see Sti1L(*991).

” CASSEN (197X) sug alreadyapparenrin ndlam the 1970s f .-

ested that rxsing agricultural costs were

” LELE &- -STONE (1489). The paper cites and discusses examples of improving and dcrerioraring situations. See also chaDrer 2 (Ho. T . 1. Population nrowch and aericultural

much of the environmental destruction has been due to factors other than population. Road construction through forest areas, for example, often measures in ad- vance only the forest area to be cleared for the road itself, and does not allow for roadside setrlement which follows the new economic opportunities presented by the road; the latter often results in large tracts of deforestation. Governmenr policies, technological change, even land re- forms unsupported by appropriate productivity measures have all been blamed for environmental damage (see DASGUPTA & M&~R, 1990). Wood fuel requirements for cooking, on the other hand, are strongly population- related--though here again the extent of damage de- pends on whether favourable change does or does not fol- low population growrh.

Many of the relevant features of the rural economy in developing countries are described under the rubric of ‘the management of common properry resources’. Very often traditional communities do have adequate systems of management of such resources; but these quite com- monly break down under ~opularion pressure. Here a crucial factor is whether at er commututy management can be strengthened, or property righrs become vested in individuals so that they have incentives for appropriate management. The fuel-wood situation is affected by these and other features. Many communities show con- siderable ability to substitute other fuels for wood, or adapt by other means, when wood is scarce (see, e.g., DEWEES, 1989). If markets in wood develop, and grow- mg it becomes profitable, farmers will devote a share of their land to trees15. Once again, experience is variable, and population is far from being the sole cause of prob- lemsin ~ommonpropertyresourcemanagement.l6

The urban problem is more clearly population related, though of course the nature of development, incentives and policies also play a part. The very rapid growth rates of urban populations in developing countries have partly to do with natural increase rates, and partly with rural- urban migration”, which is obviously affected by the character of rural development and the relative arrrac- tiveness (from pay and other points of view) of urban life. It is possible to produce nightmare scenarios of the urban future based on simple extrapolations of the pasr, showing huge urban agglomerations developing with in- superable problems. In fact cities in a given country will tend to follow S-shaped growth curves; as the larger ones reach the flatter u

5: as growth uoles.’ per part of the S, other cities take over

And as rural develotxnenr Droduces staGdards df living closer to those of the cities, Migration rates decline.

Economic development in fact tends to improve most aspects of urban lifedventually. Urban sanitation, housing and air quality are all things that improve as in- comet rise, (WORLD BANK, 1992 [chapter 11; BBCKER-

“T’& candiit%n;c$nder which population grawrh induces or fO

obviously favourable accorn~n;~lmg c+nges are

exrremc1v comdex. attrlbuuon of envlronmenral damage to population growth will depend on whether such change is incorporated m one’s ‘model’ as a variable or as a constraint, and appropriate specification of tie initial condzrions, favourable or unfavourable. Clearly tie arrrlbution of d-age m population growth in a view such as That ofKlNC <1990) is overly simplistic.

" See chaprer 3 (Barnes, D. F., Popularion growth, wood fuels, and resource oroblems) in ACSADI ef or. 11990‘1.

I6 Other fact&s inclube ;z;kzn

goyernme~n! . po&ies;- migration

f from drought, confl~cc or cwxlunresr; r+ngmarker

or natural resource products and ensu,ng ourwd~ entrepreneurialororherinterests.

“One should not exazzgerare the role of mimarion. Not surprisingly, escimare;shaw rhar cities grow -fastest when national popularions are growing fasresr.

" CASSEN (1987) observed that the central wards of Calcutta Losr population between the 1961 and 1971 censuses. Rural-urban migration is usually analysed in terms of ‘push' and ‘pull' factors; as Ashish Bose, the distinguished Indian put ir,

saciologisr, with Indian aties one has to reckon w,th rhe

‘push-back’ facror.

MAN, 1991), though the latter (and of course transport- ation problems) go through periods of worsening until remedies are achieved. ‘Eventually’ is, however, rhe key word, and the abysmal conditions of life in most ‘Third World’ cities in their phase of rapid expansion need no emphasizing here.

Nightmare scenarios are sometimes aozompanied by huge and unaffordableestimates of investments requiFed for improving urban environments. In fact when low-cost rech- nologies and cost-recovery techniques are taken into ac- count, many desirable measures seem much more within reach. And when benefits are taken into account, they can often be shown to be even more desirable: manv of the urban pollution effects of rapid population growth a& major health hazards, and also reduce labour productivity. WORLD BANK (1992) cites the extreme case of Peru, where the losses of agricultural exports and tourism earnings in tie iirst ten weeks of the 1991 cholera epidemic were 3 times the entire amount invested by the cou&ry in wa!er and sani- tarion during the whole of the 1980s; less extreme cases in- dicate hiih pay-offs to public invesunent on these items. It also cites studies from Africa? Asia and Latin America showing tbac individuals at all uxome levels are williig 10 pay much more than is conunonly thought for household water and sanitation.

It seems rhat there is a cycle through which all coun- tries go, during which cities move through periods of in- tense environmental stress, after which most-if not all-things gradually improve. It is clear that the ma- jority of the problems are population related; automotive pollution is the most obvious feature which is mainly in- come related. This apart, economic growth tends 20 im- prove the urban environment-again, one must add, eventually. And appropriate policies and technologies can do much to mitigate the damage of urban growth.

As noted above, a rapidly growing labour force will make for intense labour market competition; this is not the condition for a high wage economy with rapidly in- creasing living standards. At the household level, large numbers create difficulties in achieving better health and education; productivity is consequently likely to be low. At the same time, with few resources of other kinds, par- ents are likely 10 see children as potential sources of fam- ily income. High fertility is rightlv seen to be both a con- sequence and a cause of poverty

Many of the adverse ecological trends observed in de- veloping countries are in considerable measure artribut- able also to poverty. In rural areas, it is the poor who de- pend on many of the comon property resources for consumption and livelihoods, and their growing numbers subject these resources to sfress. Time horizons are typi- cally short for poor peoplelg, and mining of resources rarher than attention to conservation is conunon. In urban areas also,. the conditions in which the ooor live conrribute a la&e share fo urban health and other ha- zards; the poor are also rhe main sufferers from pollution and lack of clean water and sanitation.

Families may be doing what they see fo be the best for themselves; but the outcome of large numbers of families doing the same is something of a self-perpetuating syn- drome, passing from one generation to the nexr. It is surely absurd for the ‘revisionists’ to suggest that high fertdity in these circumstances is anything oiher than harmful. But provided no threshold of irreversibility is passed, societies will emerge from these conditions. Eca- notic developmenr provides the resources for coping with environmental problems at large. It also brings to the individual both resources and motivation to alter fer- tility behaviour. A critical transition occurs as parents change, from looking at children as earning assets for the

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family in the near term, to putting a high value on their children’s future in the long term-something they can- not fulfill for large numbers of children.

One furrher iabour market aspect deserves a brier mention. Eecause of international trade and investment, the low wage economies of developing countries do exert some downward pressure on living standards, particu- larly those of the lower paid individuals, in the tndusrrial countries. The industrial worker in our societies has an interest in lower population growth and rising wages in developing counties (KING: 1991).

If living standards in these countries do not improve, and population growth condnues at high rates, one of the consequences may be increasing social and political fur- mail. Particularly in already populous countries where ethnic and other tensions are severe, rapidly increasing city size and population densiry without social progress can impose swains on gover-ent and people which make it difficult to carry our the wise policies on which improvements depend. The economist does not normally include governmental and institutional capacity in the analysis of economic development under rapid popula- rion growth; but these may prove to be critical con- straints in some countries.

It has fo be accepted that world population is going to grow considerably--to some 10 bilhon by 2030 under the World Bank’s ‘base case’ scenario. Even with ‘ra id fer- tility decline’ it will reach some 8 billion. The dl ference -P made by the time stable population is reached in the mid 22nd century is some 2-5 billion (12.5 as opposed to 10 bil- lion) (WORL.D BANK,, 19923. The rapid fertility decline fax is quite implausible; It appears that the difference which can be made to population rowth in the neare* term is rela- tively modes@. Every e B art should, nevertheless, be made to contain that growth, since the difference which resulrs in the longer term is very l~~tbe ‘slow fertility decline’ case does not much differ from the base case by 2030, but by 2160 the difference is more than 10 billion over the base caee(22-5biUionasopposedto 12-5 billion).

Econoxnic development will improve some aspects of life and environment, and-at least at first-worsen others. The WORL.D BANK (1992) suggests that it can all be accomplished without environmental disaster, given appropriate policies and research efforts; for a different but also balanced view see HARRISON (1992). This may well be correct; but it is hard to be confident that all the good things which have to happen will in fact happen. Good policies require stable governments, information, analytical capability, and people to carry them our, many of which are lacking in many countries. The social and political difficulties which may be caused by further population growth may themselves complicate the task.

Rapid population growth poses many threats fo indi- vidual and global well-being. l3ut as far as the global en- vironmenr is concerned, it is by no means impossible chat the behaviour of the industrial caunrries, where popula- tion will barely grow at all, will do the larger share of drastic and irreversible damage. Controlling the environ- menral effects of their economic growth is porentialjy hugely expensive, and by the time enough is known to convince policy-makers that action must be taken, it could be too late. Global warming, ozone depletion, acid rain-these are among the effects which do not improve with economic growth, or at least have not done yet. It must be hoped that developing countries will not make the same errors; they will at least be able fo learn from those aho are further down the path.

2oTherc is of course the major unknown factor of AIDS. BONGAARTS (1989) suggesrs chat it could increase the death rare in sub-Sahara" Africa by 10 poinrs per 1000 abovewhat it would otherwise have been by the year 2010; in axher ward--lf there were no cansequence for fertility-it would reduce papularion growth by 1%; bur see GARNET-~ 81 ANoEnsoN(1993).

Sl/l8

Ackmwledgements I am indebted to Will Cavendish, Peter Dew-3 and Gaie

Mendelssohn for helpful com.nen~s.

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