Excessive Human Population Growth and Human Geneticists

Genetics, Environment, and Social Problems A View from the Third World

by Francisco M. Salzano, PhD.

Dr. Francisco Mauro Salzano is the recipient of the 1973 medal of the Silver Jubilee of the Brazilian Society for the Advancement of Science. In 1994, he received the National Award in Science and Technology, the highest honor the Brazilian Government confers to its scientists. During the same year, the Laboratory of Molecular Genetics at the Center of Biologic Sciences of the Federal University in Para, Belem, was named in his honor and in 1995 he was conferred the Grand-Cross Class of the National Order of Scientific Merit of Brazil. These are but a few of the awards earned by our colleague. Born in Rio Grande do Sul, Brazil, Dr. Salzano obtained his Ph.D from the University of Sao Paulo, Brazil and started his scientific career in genetics as a Drosophila investigator. After a fellowship with Dr. James Neel, Dr. Salzano focused on human population genetics with an emphasis on South American Indians. The multifaceted investigations by Dr. Salzano are described in nearly 400 scientific papers, numerous reviews, articles, chapters and 11 books.


An examination of the world today shows a worrisome picture. Rich nations, where indiscriminate consumption is the rule, coexist with countries where standards of living vary from luxury for a few to abject poverty for the many. Such differences are intrinsically unethical, negating the principle that all should have access to a worthy life. The excuse that such differences always existed and will continue to exist due to diverse biological abilities of the inhabitants of such nations (superior or inferior races or ethnic groups) was demonstrated as erroneous a long time ago. But the problem remains since, in many cases, the high standards of living of the First World countries is maintained because the First World imports low cost unprocessed materials and then sells the finished products at high prices in all markets.


How can this picture be changed? Two concepts emerge here. The first is the idea of progress, which could perhaps be defined as "directional change towards the better" (Ayala, 1988). This idea did not appear in human history until the Renaissance. Greeks and Romans of antiquity visualized the world in terms of eternal cycles, while Christian theology considered human history as a period of suffering between Adam's fall and the Final Judgement. The application of the concept of progress in biology is controversial. Gould (1988) stated that "progress is a noxious, culturally embedded, untestable, nonoperational, intractable idea", but less extreme views were presented in Nitecki (1988).

Another concept is that of development, which received the blessing of the United Nations. In this organization's constitution, approved in 1945 (article 55), the words progress and development appear together: "The United Nations will favor the raising of standards of living, full employment, and conditions of progress and development in the social and economic order...". Since then, however, the word progress no longer appears in U.N. documents. Roche (1986) asserted that in scholastic Aristotelic terms progress implies a final cause, which is now not believed, while development is seen as the conversion of a potential into something actual, like the embryo that grows and diversifies, or an exposed photographic plate that is revealed by the effects of certain chemical products.


Bunge (1980) maintained that a human society is a system that can be analyzed in four main subsystems: biological, economic, political and cultural. Biological development would involve raising the well-being and health of a population, as a consequence of improvement in nutrition, housing, clothes, habits of exercise and sharing, etc. The economic concept of development holds industrialization as its objective. In the political arena the goal is the expansion of freedom, to assure increased human and political rights. Finally, cultural development presupposes cultural enrichment and the diffusion of education. But what is important to stress is that each of these subsystems interacts with the others, and that what is imperative is the simultaneous progress of all of them.


The word science may have different meanings. It may transmit the idea of its method, the facts and theories it considers, or its social institution (that is, people and organizations that "make science"). In all its senses, however, science is a social process. Therefore, "scientific and political questions are inextricably interconnected and dialectically related" (Levins and Lewontin, 1985). Three other sentences of the indicated authors are also worth considering: (a) "Modern science is a product of capitalism"; (b) "There was a commoditization of science"; and (c) "The 'pursuit of happiness' (that is, profit) implies the right to exploit".

To my mind, the development of a more just society implies changes in its socioeconomic system that could alter this state of affairs. To achieve that we must transcend biology. Dobzhansky (1956) rightly stated that "Ethics are a human responsibility. We cannot rely on genes or on natural selection to guarantee that man will always choose the right direction of his evolution".


A series of points of contact between genetics and social problems is presented in Table 1.

TABLE 1 Points of contact between genetics and social problems

  • Biological determinism
    • 1.1. Sexism
    • 1.2. Racism
    • 1.3. Legitimization of social inequalities

  • Health and disease
    • 2.1. The relaxation of natural selection
    • 2.2. Agriculture to whom? Pesticides
    • 2.4. Mind's adjustment -- mental disease
    • 2.5. Aging
    • 2.6. Gene therapy
    • 2.7. Violence
    • 2.8. Inbreeding and incest
  • Population control and eugenics
    • 3.1. The "thinking envelope" or noosphere (Dobzhansky, 1967)
  • Who owns life?
  • Artificial intelligence
  • Questions of identity and parentage

It is of course impossible to discuss all of them here. Just the eight points of the dialectical relation health -- disease would merit a large book. A hotly debated question is that related to biological determinism. Would we be just automata, rigidly controlled by our genes? If this were true, unfavorable positions in society due to sex, race or social class would be legitimized. A vast literature is available against this view. Rose (1989) stressed that to build a new science, male dominance should no longer rule, stating that "nothing less than half of the laboratories" should be the province of women scientists. Questions of race definition and racism were discussed in Salzano (1997), while Lewontin et al. (1984) considered the relationship between genetics and politics.

The problem of population expansion and its eventual control will be examined below. Another question: Who owns life? Should DNA segments be patented and transformed into commodities? On the positive side, we have the development of DNA computers much more efficient than the present ones and of machines of artificial intelligence. Progress in the efficient identification of tissue aliquots of living persons or human remains, on the other hand, is furnishing important tools in the solution of crimes and in determinations of paternity or maternity.


What is the value of a cubic meter of air, or of water, or of biodiversity? This question was recently raised by Garcia (1995). Evidently, it is impossible to establish an exact value. However, he added, while the price of a gram of gold is calculated at about 12 dollars, one gram of raw chlorophyll is worth 700 dollars, and one gram of purified chlorophyll 20,000 dollars.

Let us now consider biodiversity (Erlich and Wilson, 1991). About 1.4 million species of plants, animals and microorganisms have been described. Terrestrial and freshwater diversity is higher than that found in the seas. The most numerous elements are the flowering plants (220 thousand species) and their coevolutionary partners, the insects (750 thousand species). But the known diversity is just a fraction of the total. It is estimated that the total number of species in our planet is around one hundred million.

Certain taxonomic groups present hyperdiversity, and the same is true in relation to some habitats and geographical areas. For instance, 300 species of trees were found in just one hectare of land in Peru, while only 700 were described in the whole of North America (Erlich and Wilson, 1991).

Why should we worry about the maintenance of this biodiversity? The above indicated authors suggest at least three basic reasons. The first is ethic and esthetic. Since Homo sapiens is the dominant species on earth, we have a moral responsibility of protecting our fellows in the universe. It is notorious also that observing and living together with them generates esthetic and gratifying feelings.

A further reason is that humanity already has obtained enormous economic benefits from this diversity, in the form of food, medicines, and industrial products, and potentially can obtain much more. Thus, just a small fraction of the plant species has been investigated in relation to their pharmaceutical value; and while we have used about seven thousand species as food, at least several times this number of species show edible parts.

Finally, a whole series of benefits are provided by the natural ecosystems, which ensure the stability of climates, waters, soils and nutrients. Biodiversity plays a role so critical and on such a large scale that it is difficult to suggest dispensing with even the most simple organisms, lest an imbalance result.

Despite that, there is a continuing irreversible loss of species, and by 2100 the loss may reach one-third of all species now living. Loss of soil productivity, which is causing extensive land abandonment, is a widespread by-product of current practices in agriculture and animal husbandry. Since 1945, 11 percent of the earth's vegetated surface has been degraded, an area larger than India and China combined, and per capita food production in many parts of the world is decreasing (Union of Concerned Scientists, 1997).

Another problem is one related to the emergence of new diseases and reemergence of old ones. People may wonder why, in a body so well structured as ours, there are thousands of failures and weaknesses, making us so vulnerable to ailments. To analyze that we must remember that there are immediate as well as evolutionary causes for illnesses. Immediate explanations answer questions of the "what" and "how" type, while evolutionary explanations answer "why" questions. Our relationships with the emerging and reemerging infectious diseases may be compared to an unending arms race. There are continuous adjustments of hosts and parasites, making outcome predictions hazardous. To illustrate, one-third of all cases of tuberculosis arising in the city of New York are caused by bacilli resistant to one antibiotic, while three percent of the new cases and seven per cent of the recurrent cases are resistant to two or more antibiotics. The survival probability of persons with tuberculosis resistant to multiple medicines is about 50 per cent, the same as before the advent of antibiotics (Nesse and Williams, 1997)! Standards of development, life quality and associated factors are of decisive importance in deciding who wins this arms race.


How can we justify the fact that we can feed an astronaut in remote space and build tremendously expensive instruments of death and destruction, but are incapable or feeding or vaccinating Third World children, or those at the periphery of large cities? Perhaps the worst environmental contamination is that of a mental nature.

Let us consider the expenses of all nations for military purposes. United Nations statistics cited by Roche (1986) estimated that the costs in the manufacture of improved weapons are of the order of 1.5 million dollars per minute! This same author mentioned that just the cost of a F16 airplane (25 million dollars) is equivalent to the annual budget of the World Health Organization for research in tropical diseases, which affect millions of human beings.

Information from other sources are equally impressive. Consider the following, extracted from Webster (1996): (a) Over 12 years, 126 atomic weapons were detonated at the Nevada Test Site. Each of these explosions would spread roughly the radiational equivalent of Ukraine's 1986 Chernobyl reactor fire across America. It is estimated that 400,000 deaths due to this atmospheric radiation will occur by year 2000, killing twice as many persons as those who died in Hiroshima and Nagasaki; (b) Since 1963 at least 828 underground tests have been conducted at this same site, dimpling the earth and making 1,350 square miles of American Desert uninhabitable for the next 5,000 years; (c) The U.S. detonated the equivalent of 250 pounds of dynamite for every person living in Southeast Asia, dropping more bombs than were used by all sides in World War II. Not less than 100,000 bullets were expended for every North Vietnamese soldier killed.

Finally, the United Nations database yields an estimate of 110 million land mines scattered through at least 70 nations where 20,000 people die each year from their effects (Doughty, 1997).

In contrast with all these expenses, at this moment one person in five lives in absolute poverty without enough to eat, and one in ten suffers serious malnutrition (Union of Concerned Scientists, 1997).


"The earth is finite. Its ability to absorb wastes and destructive effluent is finite. Its ability to provide food and energy is finite. Its ability to provide for growing numbers of people is finite. And we are approaching many of the earth's limits". This text of the Union of Concerned Scientists (1997) speaks for itself. According to the same source a World Bank estimate indicates that the world population will not stabilize at less than 12.4 billion, while the United Nations concludes that the eventual total could reach 14 billion, a near tripling of today's 5.4 million. Neel (1997; 1998) estimated that if every couple would start today to have just two children the population at year 2030 would reach 6.7 billion. Earlier and in his 1998 paper he also made a plea for establishing a worldwide two-child noneugenic policy. This is a perfectly ethical proposition.

Many persons would agree with Smil (1993) who stated that "it seems impossible to believe that increasing crowding of people may lead to an improvement in life quality". Some, however, hesitate to make global evaluations, because the future of the world population really depends on what is going to happen in just ten or fifteen developing countries, each with its own peculiarities. Therefore, carrying capacity estimates would only make sense in the context of specific historical and political entities (Martine, 1996). The crucial point is the type of civilization which mankind is building.


In relation to the population issue two polar positions can be envisioned. NeoMalthusians believe that the size and/or growth rate of the human population is the most critical factor causing environmental degradation. According to them, food production cannot keep up with population forever, no matter how fast new technology develops. The nonMalthusian position, on the other hand, asserts that human population is only one, and not necessarily the most important factor influencing environmental degradation. In relation to the other variable of the problem, food production, here again two opposing positions can be distinguished, those who emphasize the role of increased production in the improvement of living conditions, against those who doubt that increased production per se would have much effect.

Four contrasting views of the problem can therefore be envisaged (Table 2).

TABLE 2 Rate of change in caloric input and key variables
Key variable
Observed (%)




Domestic product

Agricultural growth

Income inequality

Population growth







Source: Buttel and Raynolds (1989)

The productionist nonMalthusians would maintain that there are no ecological limits to economic growth. The productionist neoMalthusians would agree that increased production is the key, but they would see population growth as the main factor limiting the adequate increase in production. The nonproductionist nonMalthusians would regard the distribution of resources as the most important factor. Lastly, the nonproductionist neoMalthusians would maintain Malthus's original argument, that the size of the population or its rate of growth is what matters.

Buttel and Raynolds (1989) performed an analysis considering the rate of change in food consumption and variables regarded to be the key ones for each of the positions outlined. Using data from Third World countries they arrived to the figures shown in Table 2. As can be seen, the evidence favors the nonproductionist nonMalthusian view, through the higher correlation coefficient obtained between change of caloric input and the key variable considered.

TABLE 3 Selected demographic and economic variables observed in
First World and Third World countries
Birth Rate
Gini coefficient
Poorest 20%
Richest 20%
South Korea


Third World
First World
Population density
Birth rates (per 1,000)
Source: Vandermeer (1996). GNP: gross national product; Gini coefficient is an estimate of the relative concentration of wealth; it would be 1.0 for a completely concentrated system and 0.0 for a perfectly equitable one.

Another analysis was performed by Vandermeer (1996). He considered 18 First World and 40 Third World countries, and selected examples of his list are presented in Table 3. The nations are arranged in relation to their gross national product (GNP) per person, as compared to that of the United States. South Korea has the highest GNP for the Third World, with 39 per cent of the USA value, while Spain has the lowest for the developed world, with 57 percent. Population density varies independently of this ranking, and as a matter of fact is on the average higher in the First World than in the Third World countries considered (140 vs 107 thousands of people per 100 hectares; Table 3). But birth rates are lower in the First as compared to the Third World (14 vs 33 per thousand per year). In the Third World the richest 20 per cent of the people have ten times more the wealth of the poorest 20 per cent, while in the developed world the privileged class has only seven times more than the lower 20 percent. The picture related to Gini coefficient is somewhat complex, but in general inequality is smaller in the First World.

Vandermeer (1996) obtained some interesting results when the Gini coefficient of these nations was compared with their GNP. The developed world is characterized not only by a relatively high GNP, but also by a more equitable distribution of income, as compared to the Third World. South Korea is clearly in the middle of these two block distributions. Furthermore, there are nine countries that are characterized by very high inequality and very low GNP, namely Guinea-Bissau, Kenya, Zimbabwe, Honduras, Lesotho, Guatemala, Dominican Republic, Senegal and Brazil. Five African and four Latin American countries are therefore in this vexatious condition, and as a Brazilian I can only hope that the situation in my country may change soon.


There are many roads to a harmonious socioeconomic development, and a given community should have the right to choose the one that suits it best. Many points of contact exist between genetics and social problems, and they should be carefully considered as our life becomes more and more "geneticized". Development should not be constructed at the expense of our environment's degradation. Increased population numbers is just one of the problems facing mankind, in its struggle for survival and better life quality. Income inequality is of crucial importance, and should be considered in any program designed to fill the gap between developed and undeveloped countries. The principle of the maximum of happiness to the largest number of people should be actively pursued, and adequate policies implemented at all levels of our societies, independently of gender, ethnic or national affiliation, and position in society. Geneticists and non-geneticists have a duty, as citizens, to consider these matters and to influence government officials towards these goals.

My research is financed by Programa de Apoio a Nucleos de Excelencia, Financiadora de Estudos e Projetos, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, and Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul.


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  2. Bunge, M. 1980. Ciancia e Desenvolvimento. Sao Paulo: Itatiaia e Editora da Universidade de Sao Paulo.
  3. Buttel, F.H. and Raynolds, L.T. 1989. Population growth, agrarian structure, food production, and food distribution in the Third World. In: Pimentel, D. and Hall, C.W. (eds.) Food and Natural Resources. New York: Academic Press (Cited in Vandermeer, 1996).
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  6. Erlich, P.R. and Wilson, E.O. 1991. Biodiversity studies: Science and policy. Science, 253:758-762.
  7. Garcia, E.S. 1995. Biodiversidade, biotecnologia e sa?de. Cadernos de Sa?de Publica, 11:495-500.
  8. Gould, S.J. 1988. On replacing the idea of progress with an operational notion of directionality. In: Nitecki, M.H. (ed.) Evolutionary Progress. Chicago: University of Chicago Press, pp. 319-338.
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  13. Neel, J.V. 1998. A further look at the worldwide population/resources problem (this publication).
  14. Nesse, R.M. and Williams, G.C. 1997. Por que Adoecemos? A Nova Ciancia da Medicina Darwinista. Rio de Janeiro, Campus.
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  16. Roche, M. 1986. Ha contribuido la ciencia al desarrollo? Interciencia, 11:216-220.
  17. Rose, H. 1989. Nada menos que metade dos laboratorios. In: Rose, S. and Appignanesi, L. (eds.) Para uma Nova Ciancia. Lisboa: Gradiva, pp. 221-242.
  18. Salzano, F.M. 1997. Human races: Myth, invention, or reality? Interciencia, 22:221-227.
  19. Smil, V. 1993. Global Ecology: Environmental Change and Social Flexibility. London: Routledge.
  20. Union of Concerned Scientists. 1997. World Scientists' Warning to Humanity. Cambridge: Union of Concerned Scientists.
  21. Vandermeer, J. 1996. Reconstructing Biology. Genetics and Ecology in the New World Order. New York: John Wiley & Sons.
  22. Webster, D. 1996. Aftermath: The Remnants of War. New York: Pantheon Books.

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