• No results found

GENETICS AND HUNGER

N/A
N/A
Protected

Academic year: 2020

Share "GENETICS AND HUNGER"

Copied!
10
0
0

Loading.... (view fulltext now)

Full text

(1)

Symposium on Genetics and Society: X I I I Interr@ionul Congress of Genetics

GENETICS AND HUNGER

RICHARD LEVINS

Department of Biology, University of Chicago, and Chicago SESPA

HE most surprising fact about agriculture is that it sometimes feeds people, Tthat hunger is not more widespread than it is. This is surprising because in most of the world today food production is not engaged in to feed people, food does not flow from well-fed areas to hungry areas; fluctuations i n food produc- tion do not follow changing needs. EHHLICH and EHRLICH (1970) have pointed out that there is a net flow of protein from “developing” to affluent countries. In years of bumper harvests such as 1969, the price of grain falls to the point where it can be used to feed cattle and be converted to animal protein for the well-fed. In bad years prices rise, black marketeers buy up supplies, and the inequality in distribution is accentuated.

Further we can assert that agricultural programs and agricultural research are not usually aimed at feeding people either. The former are determined in order to stabilize the balance of payments (DALRYMPLE and JONES 1973) or to obtain natural gas, o r as in the fire ant control program to show that the Department of Agriculture loves farmers. Levels of production are set at international confron- tations of producers and consumer nations. Departments of Agriculture usually function to serve the farmers as a political consistency, and this generally means the richer farmers.

The main effort of agricultural research is the production of marketable com- modities that can be sold to farmers-insecticides, fertilizers, or machines mostly. The feeding of people is a by-product of all this, predictable insofar as food is edible, but a by-product nonetheless and very uneven across space, time, and social class.

Therefore, our professional pride notwithstanding, agricultural genetics is neither the key to human happiness nor survival that we are expected to claim at international symposia. Nor is there the direct relation between plant or ani- mal breeding and human hunger that we would expect when we resort to the linear syllogism: food relieves hunger, crops yield food, therefore improving yields reduces hunger. An agricultural science which really serves people’s needs must have a broader base than plant biology and a more complex view of the world.

But if all this is true, if food as a commodity prevails over food as nutrition, if land as investment prevails over land as productive soil and science as product development predominates over science as understanding aimed at freedom from want, if the locus of hunger is in political economy rather than entomology, why do we bother to look at genetics? I think there are several good reasons:

(2)

68 R. LEVINS

1) There already exist large areas of the world in which food is in fact

the

direct purpose of agriculture; where fluctuations in food production are reflected immediately in available supplies; and where advances in agricultural science are directly advances in people’s well being. Many of these areas are tropical, and here where our understanding is still minimal, a new agricultural science is most urgent and most possible.

2) Our claim that agriculture is a social and political science does not make it any less a biological science. Rather we insist on the inseparability of the biology and politics in a single science. This inseparability is both necessary for under- standing agriculture and for transforming it, for positive planning and for critique.

3) Agricultural research which assumes as a boundary condition the prevail- ing social structures of agricultural production and land use patterns also rein- forces and intensifies these structures and patterns, while restricting the scope of its own imagination to the narrowly practical. But research which looks a t the whole system, which is willing to confront any incompatibilities between eco- nomic reality and ecological necessity, underlines the great gap between the present and the possible and may itself become an instrument of social change. There is today a broad, diffuse dissatisfaction with the state of agricultural research. In the U.S., a study by the National Academy of Sciences emphasized the lack of fundamental results coming from agricultural laboratories. DANIEL

JANZEN

(1973 j reviews tropical entomological investigation. He found that most contemporary works on tropical agriculture ignore insects, that accounts of

insects which feed on crops are mostly compendia which ignore the interactions of inseects and crops, and that studies of economically important insects have become part of the advancement ritual in bureaucratized civil service science.

The generally unsatisfactory state of agricultural research does not imply that agricultural researchers are of low quality. Rather, the administrative and intellectual settings in which they work prevent the full development and expres- sion of their talent and enthusiasm.

Several aspects of this malaise are worth examining.

SEPARATION O F BASIC A N D A P P L I E D RESEARCH

(3)

GENETICS A N D HUNGER 69

such as the development of the new high-yield varieties of wheat, rice, and corn have been the result of massive varietal testing and crossing with only negligible use of any insights after Mendel’s. Meanwhile, in the urban centers of “funda- mental’’ research there is little incentive or interest in serving agriculture, and a strong snobbery toward applied research, toward organisms of economic signif- icance, and toward colleagues in these areas.

It is not therefore surprising that there are two cultures in American biology (three, if we include the medical sciences) with only sporadic communication between them.

If the separation of fundamental work in biology from agricultural research is harmful to U.S. agricultural science, it is even more dangerous to the countries which are only now emerging or trying to emerge from colonialism. The urgency of many of the problems they face encourages the idea that it is possible to be consumers of basic research done elsewhere, and to emulate and try to transplant the structures of applied research current in the U.S. But the basic research needed for tropical agriculture is yet to be carried out. The pattern of

U.S.

agriculture-the introduction of large scale commercial farming based on very high input of energy, chemicals, and machinery-is a dangerous one: it creates dependence on imports, threatens the ecology and health, exhausts the soil, and perpetuates the intellectual colonialism which is retarding the development of

new centers of scientific imagination.

A rapprochement between agricultural research and basic research in genetics and ecology might take place along the following lines:

1) Workers in fundamental areas can discover the possibilities of agricul- turally relevant systems for basic science. There is a large scale surveillance of economically important insects by county entomologists, giving distributions of pests in time and space on a scale that would be impossible to achieve for Drosophila; Agricultural systems are historically new, so that processes of adapta- tion in new environments are taking place rapidly and we can study non-equilib- rium genetics and ecology of populations most readily in pests; even speciation can be caught in the act as insects adapt to new hosts and lose contact with the parental gene pool (as in the case of the apple maggot fly Rhagoletis)

.

Cultivated fields are as close to replicate patches as we can get on a large scale, so that they are ideally suited for the testing and development of biogeographic principles which up until now have been limited mostly to islands. And the realities of agricultural practice can focus theoretical work toward dealing explicitly with seasonality in a way that neither continuous nor cohort models of genetic change and population fluctuation have so far handled.

(4)

70 R . LEVINS

This lack of direct concern with basic theory has two sources, one in the ideology of empiricism and pragmatism which dominates applied research, and the other in the fact that the basic theory, developed for other systems, often really is inapplicable or at least not obviously applicable to the needs of agriculture.

Pragmatism

In our society, “pragmatic” is usually a term of praise. It suggests a straight- forward no-nonsense tackling of solvable problems, a sense of realism which accepts the realities as given and is not diverted by ideal goals, philosophical speculation, or ideological commitments. But in practice, it means indifference to long-range considerations, acceptance of the real as rational, and ultimately the reinforcement of the present conditions.

Consider for example, some aspects of mechanization. Given that corn in the midwest is planted in pure stands, the farm machinery is designed for handling pure stands. Then, when we consider farming systems for the area we cannot seriously study mixed cropping since the machinery would be unsuitable. That means further that it would be impractical to breed pairs of crop varieties specifically f o r mixed planting. But unless the varieties are bred for their inter- action, the possibilities in this system cannot be demonstrated as practical options, and the attempt is unlikely to be made. Even when the theoretical possibility is

demonstrable, the argument “how would you sell that to an Iowa farmer?” is enough to cut off the curiosity.

The fallacy in the pragmatist’s approach is that the world is not a series of independent problems among which some can be chosen to solve because they are relatively easy, while others can be left unchanged for the future. Rather, there are feedback loops at work such that the acceptance of the constraints of the present, unless these are also subjected to criticism, results in their reinforcement.

When we criticize the existing patterns of agriculture, or dependence on insect- icides, or the strategy of plant breeding, we are legitimately asked, what are the alternatives? Clearly contemporary plant breeding gives improved yields over no plant breeding and insecticides do control some pests at least on a short term basis. Therefore a criticism of the actual must be made by comparison with the possible rather than with doing nothing. But the possible-the agricultural

systems based on integrated pest control, breeding of plants for their role in the ecosystem, application of the variability of microclimate-the possible alterna- tive is always pale compared to the actual. This is especially true when the possible exists less as concrete knowledge than as general principles that are still to be researched. As long as the main emphasis of research is along the lines of current practice, the proposals for change will necessarily seem way out. The pragmatic approach to agricultural research is self-reinforcing.

E M P I R I C I S M

(5)

GENETICS A N D H U N G E R 71

a ) the separation of fundamental and applied work in different institutions and cultures, discussed above.

b) the growing organization of research along industrial lines, with projects, subprojects, and subsubprojects clearly defined and assigned; this makes it seem natural that researchers do their job and don’t worry about consequences or contexts. I n particular, the scientific output as a commodity defines the boundary

of interest as the boundary of financial responsibility.

c) the vocational emphasis in education, which prepares people for their future employment on a narrow need-to-know basis.

d) among those who are most concerned with human well-being, there is a sense of urgency which very easily becomes impatience with intellectual detours, a demand for relevance which ignores the rich interconnections of things and processes.

The empiricist strategy continues in the tradition of secondary school general science to insist that problems should be made as small as possible, the chunks should be treated in isolation, things varied one at a time. It also insists that the variables of ultimate concern must also be the variables which provide the under- standing of the processes. Therefore in order to improve yields we measure yield. But theoretical constructs one step removed from the objects of interest are generally treated with suspicion. Among the theoretical constructs of genetics and ecology only heritability has been incorporated into the working common sense of plant breeding.

Our criticism of the existing pattern of agricultural research in the U.S. is not that it never helps food production, but that it is self-limiting, that its organiza- tional structure and prevailing ideology necessarily emphasize short-term one- step modification of existing agricultural systems in a way that excludes from consideration the indirect consequences of these changes, ignores the possibilities latent in theoretical work, and fragments agricultural science into narrow specializations each of which loses a global overview.

The case f o r an alternative approach to research will be supported around a brief discussion of the notions of the norm of reaction, the cultivated field as ecosystem, and the biogeography of pests.

Norrri of Reaction

The fundamental insight of developmental genetics is that of the genotype as a norm of reaction, a viewpoint developed by Dobzhansky and Schmalhausen. This approach emphasizes the intimate interpenetration of organism and environ- ment as against a statistical component of variance approach which separates them, assigns relative weights, and secondarily recombines them in genotype x

environment interaction terms. Further, the norm of reaction concept frees US from giving priority to any particular environment and from thinking that there is a ccnormal” phenotype plus deviations. Rather it maps the correspondence between phenotype and a whole range of environments and shows the sensitivity of the phenotype to environmental differences.

(6)

72 R. LEVINS

viability studies in relation to temperature, and some comparisons of physiolog- ical or developmental flexibility. Yet there is a vast body of information about the sensitivity of different genotypes to environmental variability, hidden in the literature as the variance among replicates which is used as the “error variance” in varietal testing.

The notion of norm of reaction also emphasizes the genotype as part of com- plex causal sequences, as active response to environment. In this context it is easy to realize that the norm or reaction does not stop at the epidermis of a plant or animal. Thus a gene for dense foliage modulates the soil temperature at the base of a plant and the course of selection for heat tolerance in the invertebrates that live there. A gene for warning coloration is also a gene for predator avoidance and greater viability provided the predator can learn what to avoid. A gene affecting melanin deposition in the human skin also affects job opportunities, state of health, and academic achievement, but only in the context of a racist society.

We will concentrate here on the sensitivity of the phenotype to environment in relation to the strategy of plant breeding. In each case we ask, what is the effect of a gene which may increase mean yield in a specific environment hut which increases the sensitivity of the yield to environmental differences? The impact depends very much on the spatial and temporal scale of variation of the environment. Let us consider several cases:

1) The environment varies on a microscopic scale, affecting each seed or plant almost independently. This corresponds to the situation in which seed germina- tion o r early viability is sensitive to the depth of planting. Since the number of seeds is very great, random variation in depth of planting around the optimal depth does not result in year to year fluctuations of yield, but in a constant average yield equal to the yield at optimum depth minus the variance in depth multiplied by the sensitivity of the plant to non-optimal depth. An increased sensitivity to depth of planting therefore necessitates uniform planting, the purchase of a seed drill, the availability of a tractor, This in turn results in an increased difference between farms because of different access to credit, accele- rates class differentiation in the countryside and the mechanization and commer- cialization of agriculture.

2) The environment varies due to topography, with chunks of environment larger than individual farms. Then any increase in the sensitivity of a crop to environmental differences increases the farm to farm variance in production. Economic factors such as access to credit o r water vary in units of farms, so that this effect is enhanced by, and in turn enhances, class differentiation.

3) Year to year environmental variation. For small farmers, the reliability of

(7)

GENETICS AND HUNGER 73

consider not only mean yield but also minimum variance (or combine these in mean log yield).

4) Temporal variance interacts with spatial variance on a geographic scale

as well. A shift in the latitude of the storm track may make the season too dry

in some regions while improving yields in others. The social consequences of this depends on the distributive system. With the fairly easy movement of crops from regions of abundance to regions of hunger, spatial variability of the environment provides a hedge against temporal variability. But if grain from areas of abund- ance falls into the hands of speculators, a good national average yield can hide a great deal of suffering.

There are several approaches to protection against the variability of the environment. Breeding may concentrate on the physiological flexibility of crop genotypes to minimize sensitivity to the least predictable aspects of environment.

Or we might aim at the development of an array of genotypes for mixed planting, either interspersed or in adjacent stands. Or we could reduce the effective environmental variance by regulating water supply or by agronomic particles, uses of windbreaks, mulch, etc.

It is customary to treat extreme fluctuations of the environment as uncontroll- able “acts of God”. The current drought in sub-Saharan Africa, the floods which have ruined much of the Philippine rice crop, or the outbreak of cornblight in the United States are generally regarded as events outside of human control and therefore their effects are excluded when agricultural policy and research are considered. However in each case human action or inaction strongly influences the outcome. The recent increases in uncontrolled lumbering in the Philippines increases the impact of heavy rains. On the other hand a Niger River irrigation and reservoir system could have buffered the peoples of several African countries against the drought. And the widespresd use of the male-sterile corn genotype increased sensitivity to the blight.

Therefore as our technical capacity and theoretical knowledge increase, acts of God are transformed into acts of society.

There is a special kind of uncertainty introduced into agriculture by the out- breaks of new varieties of plant diseases and insect pests. Their statistical pattern may be too irregular to characterize in a useful way, but the vulnerability of a

pure stand to disease is well known. The ready natural evolution of crop pests is also unfortunately enhanced by the deliberate development of diseases as part of warfare against crops precisely in those regions of the world where crop improvement is most needed. Biological warfare against crops has not been renounced along with diseases of humans. Crop destruction, mostly chemical, is part of the Portuguese effort to retain its African empire; an American researcher won a medal for “improving” rice blast, and at least one pilot run of insect pests has been used against the rice crops in Quang Ngai province of Viet Nam last summer.

(8)

74 R. LEVINS

out the military research in this area, unmask the research projects which aim at increasing hunger in order to facilitate conquest, warn the potential victims

of the properties of these weapons, and suggest means for confronting them. AS long as some biologists collaborate in the development of anticrop weapons while the rest of us work to reduce hunger, colleagues must face each other as enemies and there will necessarily be a civil war within our science.

The notion of the n o m of reaction also leads to a different strategy in the search for genetic variation to breed from. It is now recognized that in most populations there are many genotypes which produce more or less the same phenotype and are therefore not directly available for selection. However, under unusual environmental conditions or on an unfamiliar genetic background the phenotypic variance increases-part of the latent variation is developed. There- fore a major effort in our breeding work should go toward that kind of under- standing of development which will enable us to choose those environments or backgrounds which maximize the genetic variance for particular traits. I t represents a detour which in the long run will make selection less haphazard.

Cultivated field as whole

The concept of a cultivated field as a complex living system raises several issues of genetics that are ignored when we treat it as a starch factory:

1) The component species are all evolving. In particular, pests are adapting to control techniques. This is already obvious with respect to insecticides, but holds more generally. Suppose we decide to light fluorescent lamps for two hours a

day in the cornfields to delay dispause in the corn borer. Then many individuals will continue to develop late into the fall and will be killed by winter. The survivors will be those who enter diapause despite the long photoperiod, and the entomologist will eventually reach equilibrium with a univoltine borer race that is insensitive to day length. Or consider the male-sterilization program. The obvious insect response is increased sexual selectivity against laboratory males. As sex attractants are used to lure insects into traps, visual cues should become more important in mating behavior. Tc every control scheme there is some re- sponse possible: Only by studying the genetics of mating behavior, onset of

diapause, and other parts of the adaptive biology can we anticipate the course of evolution in the target species and be prepared to continue the endless maneuver- ings in our coexistence with insects.

2) What happens in a field does not depend only on the crop and its pests. Predators, parasites, nitrogen-fixing bacteria, the mites and collembola that carry out preliminary decomposition of residues, the earthworms and nematodes are all active participants in the system; their indirect effects on crops may be as great as the less remote one-step causations.

In principle, agricultural genetics can concern itself with the genotypes of the whole ensemble.

(9)

GENETICS A N D H U N G E R 75

changes in such a way that the correlation between the relative fitness of geno- types in successive generations is negative, a population is constantly adapting to previous conditions and may therefore lose fitness when additional genetic variation is introduced to accelerate natural selection. Klassens has used this principle, as conditional lethality, to encourage the spread of genes in a pest which will disrupt the diapause response when autumn frosts come.

A more complex situation is that in which the altered genotype reduces the fitness of the whole population by way of its effects on the environment of a species. The analysis of such systems is still in its infancy. However a simple example is sufficient to illustrate this possibility. Suppoe that a density-dependent prey species coexists with a density-independent predator. The prey, a plant, can allocate energy and nutrients between increased seed production and tougher, more resistent vegetative parts. If a gene results in a greater increase in fecundity rather than loss of viability due to predation, it will of course be selected for since

it is advantageous at every predator level. But it will also increase the predator population, and the final result is a decline in the prey,

Biogeography and regional control of pests

The unit of pest control is, with the exception of quarantine programs, the in- dividual farm or field. However, for many pests the region is a more appropriate unit. For pest populations, the different fields are islands in a sea of less suitable habitat. Migration from field to field may be hazardous, and it is the balance of that migration with local extinctions on individual plots that determines the per- sistence of a pest in a region. The theory of island biogeography provides a pre- liminary orientation for pest control by the manipulation of extinction and mi- gration rates in time and space. For instance, the probability of a successful migration falls off often at least exponentially with distance. Even a moderate increase in the distance between fields of a given crop might exclude a pest species completely. Also, advances in the study of host-plant location behavior suggests that the migration rate of a pest may be reduced by interplanting other plants whose odors can confound the sensory apparatus.

The difficulty with these schemes is that it involves decision making on land use over a region, larger than the individual farm, and a strategy which may prejudice individual farmers. This is not a serious problem in countries where the units of planning are larger than the effective biogeographic region, but where farms are smaller and private, the creation of pest control districts and incentive schemes may be required.

The research strategy proposed here emphasizes the importance of whole-sys- tem analysis which crosses disciplinary and departmental boundaries as against the growing specialization and fragmentation of science; a rejection of the dichot- omy fundamental us. applied to do applied work in a fundamental way; and a recognition of the practical value of intellectual detours aimed at understand- ing, as against a short term pragmatism.

(10)

76 R. L E V I N S

how to develop agricultural research. But the ideas themselves are obvious and the obstacles to their implementation are only in part the strength of contrary ideologies. More important are the sociolog~r of scientists and agricultural tech- nologists, the administrative organization of civil service and corporate science, and the limitations of resources.

This latter condition is especially important in developing countries where the shortage of trained people and facilities results in the more conscientious re- searchers feeling overwhelmed by urgent necessity and willing to postpone their intellectual interests to solve immediate problems. Nor could a crash program to train thousands of new agricultural scientists at universities hope to meet the need in a reasonable time. The spread in agricultural scientists per capita between industrial and third world countries is two orders of magnitude. What is required may be a more drastic change in the structuring of research which permits a

large scale mobilization of the intellectual resources of a country. Once we reject the notion that the creators of knowledge must be different people, many possi- bilities open up. V.T. (1973) has reported on one of the Chinese approaches to this problem. Each agricultural commune, and each of its subdivisions, has a team of people charged with bringing scientific ideas to the other peasants. Local experimentation supplements the work of experiment stations, while exposed to scientific issues allows the peasants to evaluate proposals and train themselves to produce knowledge as well as rice. The number of “para-agricultural” scien- tists is, on a per capita basis, much greater than the possibilities for a full-time professional group even in advanced industrial countries. The Vietnamese have diffused research throughout the country by encouraging each center of teaching also to be a center of research and by training agricultural scientists most of whom return to their communes (TA QUANG Bu’u, personal communication).

Finally, we have to recognize the whole-system analysis is a frustrating and

demoralizing activity if there is little chance of the conclusions being put into practice. Where short term profitability runs counter to long range need, theo- retical work easily can become a sterile exercise. For these reasons, I suspect that genetics will become part of an integrated agricultural science which is capable of mobilizing human intellectual potential to meet the challenge of hunger, only when the social organization is such that the direct objective of agriculture is feeding people.

LITERATURE CITED

DALRYMPLE, DANA G. and WILLIAM I. JONES. 1973

EHRLICH, PAUL and ANN EHRLICH, 1970

JANZEN, DANIEL, 1973

V. T., 1973

Evaluating the “Green Revolution.” Paper

Population, Resources, Enuironment. W. H. FREEMAN

Entomological Research in the Tropics. Paper delivered at the Congress delivered at the Congress “Science and Man in the Americas,” Mexico City, June, 1973.

and Co. San Francisco.

Science and Man in the Americas,” Mexico City, June, 1973.

References

Related documents

19% serve a county. Fourteen per cent of the centers provide service for adjoining states in addition to the states in which they are located; usually these adjoining states have

diagnosis of heart disease in children. : The role of the pulmonary vascular. bed in congenital heart disease.. natal structural changes in intrapulmon- ary arteries and arterioles.

Twenty-five percent of our respondents listed unilateral hearing loss as an indication for BAHA im- plantation, and only 17% routinely offered this treatment to children with

Keywords:- Active Power Filter, Current Control, Hybrid Generation Scheme, Fuzzy Logic Controller, and Power

When tested with simulated data, the ROC curves and true positive comparison indicate that a kernel size of roughly 0.20 should show an improvement over CCA (Figure 4), but

AIRWAYS ICPs: integrated care pathways for airway diseases; ARIA: Allergic Rhinitis and its Impact on Asthma; COPD: chronic obstructive pulmonary disease; DG: Directorate General;

The aim of the study was to assess the presence of pathogenic microbes on treatment tables in one outpatient teaching clinic and determine a simple behavioral model for

It was decided that with the presence of such significant red flag signs that she should undergo advanced imaging, in this case an MRI, that revealed an underlying malignancy, which