holism and reduction in sociobiology - lessons from the ants and human culture (1991) by edward...

Holism and Reduction in Sociobiology:Lessons from the Ants and Human Culture

EDWARD O. WILSON

Museum of Comparative ZoologyHarvard UniversityCambridge, MA 02138U.SA.

CHARLES J. LUMSDEN

Department of MedicineUniversity of TorontoToronto, OntarioCanada MSS 1A8

ABSTRACT: Most research in the natural sciences passes through repeated cycles ofanalytic reduction to the next lower level of organization, then resynthesis to the originallevel, then new analytic reduction, and so on. A residue of unexplained phenomena at theoriginal level appears at first to require a "holistic" description independent of the lowerlevel, but the residue shrinks as knowledge increases.

This principle is well illustrated by recent studies from the social organization ofinsects, several examples of which are cited here. In theory it should also apply to humansocial organization. Culture is biological: meaning in culture can be approached as theoutcome of mechanism-based causation, because culture stems from individual cognition,which has a biological basis. It would seem to follow that the most effective way to studyculture is across all levels of organization from gene to society, passing repetitivelythrough a cycle of reduction and synthesis in the manner of the natural sciences.Reductionistic analysis is favored by the tendency of semantic memory and culture tooccur in discrete units that are arranged hierarchically.

KEY WORDS: Ants, behavior, culture, Holism, human, meaning, reduction, sociobiol-ogy, symbol.

INTRODUCTION

Holism is an idea that has haunted biology and philosophy for nearly a century,without coming into clear focus. Like a favorite dream it comes and goes inepisodes, its content difficult to remember and its meaning opaque, its appealrising out of the haziness and mystery that it creates. Holism implies emergence,the existence of processes at one level of organization that can be explained onlywith difficulty, if at all, by descriptions of processes occurring at the next level

Biology and Philosophy 6: 401-412, 1991.© 1991 Kluwer Academic Publishers. Printed in the Netherlands.

EDWARD O. WILSON AND CHARLES J. LUMSDEN

down. Tissue formation, we like to say, cannot be deduced from a knowledge ofthe individual cells alone; and the structure of a species community cannot bepredicted entirely from the population ecology of the constituent species. Aresidue of phenomena remains after each effort at reduction to the contiguouslevel. It would seem that nature is made to hold back on us, that new events willalways spring up beyond the reach of our primitive conceptions of cause andeffect. For long intervals at least, we can only describe these residual events, nottruly analyze them.

THE INSECT SUPERORGANISM

The problem is not one of epistemology but of method and knowledge. Themystery of holism fades to the extent that processes at the lower, foundationlevel become well known. Consider the insect colony described as a superor-ganism (Wilson 1971; Lumsden 1982; H611dobler and Wilson 1990). When thecolony is viewed from afar, slightly out of focus as it were, order seems to growalmost magically out of chaos. A seething mob of workers constructs a nestcomprising a central core of chambers for the queen and brood. They addradiating conduits that air-condition the core and tough outer walls for defense.The final structure may be a thousand or even a million times the size of thebody of a single worker, like a skyscraper made by a hod carrier. Yet thearchitecture is so precise that in many cases the species (compared withhundreds of other species) can be identified at a glance. Next we observeworkers fan out in seemingly random directions on a foraging expedition. Theyharvest food items in categories and quantities not appropriate to their personalnutritional requirements but to those of the queen and brood. How did theyknow what the rest of the colony wanted?

In brief, it is tempting to postulate some very complex force distinct fromindividual repertories and operating at the level of the colony. But a closer lookshows that the superorganismic order is actually a straightforward summation ofoften surprisingly simple individual responses. A typical example is foodcollecting in the fire ant Solenopsis invicta. When foragers are starved as agroup, they collect disproportionately more honey. When they are well fed butthe nurse workers or larvae are starved, the workers collect more vegetable oilsand egg yolk (Sorenson et al., 1985). Sugars are used mainly by adult antworkers, lipids by workers and some larvae, and proteins by larvae and egg-laying queens. Hence the fire ant foragers, which are characteristically olderworkers that have completed their service as nurses and begun to venture outsidethe nest, respond to the nutritional needs of the colony as a whole and not just asan outcome of their personal hunger. How do they monitor this generalizeddemand? It turns out that they employ a relay system based on mass communica-tion. A large group of workers additional to the foragers, the reserve workers,receive most of the food as it comes into the nest and then pass it on to othercolony members, including the nurses. When the demand the reserve workers

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encounter declines in any sector of the colony, they accept the correspondingfood less readily from the foraging workers. The foragers are unable to disposeof their loads as quickly as before, and they reduce their efforts to harvest moreof the same kind. As a result they shift as a group in their emphasis fromcarbohydrates to oils or proteins or in the reverse direction, according to theneeds of the colony. Thus the colony as a whole, the superorganism if you wish,blindly presses its needs on the individual, and the individual blindly respondsuntil the needs of the colony are met. Furthermore, the mass response is moreprecise than if each worker were to attempt to assess the overall requirements ofthe colony on its own. The worker operates by a few relatively simple rules ofthumb, but the colony, operating by mass communication, is a good deal moresophisticated. Many more examples of this kind of translation have been workedout in ants and other social insects (as reviewed in Wilson 1971; Wilson andH611dobler 1988; Hlldobler and Wilson 1990).

Neither a holistic nor a reductionist examination of the social insect economyis satisfactory all by itself; the combination is far superior to each alone. Byweaving back and forth between the colony and individual levels, we have mademore forward progress than if we stayed at one level of organization. Ashrinking residue is left behind, admittedly stubborn and protected by hard-to-measure variables, second-order effects, and chaotic reactions. But the problemis technical. There is no reason to believe that it stems from defects in humanlogic or the existence of organizational phenomena beyond easily graspedorganismic behavior summed across many members in particular settings.

THE SPECIAL CASE OF HUMAN SOCIOBIOLOGY

From such examples it is easy to see why holism and reductionism are ignoredas philosophical issues by most biologists. They are intent to tear out portions ofsystems that are tractable while ignoring the residue. Let the residue wait, theyimply, until we get around to it. But the distinction is pivotal in the case ofhuman sociobiology, which is the discipline that tries to link biology to thesocial sciences and humanities. To some writers the two modes of enquiry seemto be fundamentally incongruent, with different goals. The natural sciences,represented at the upper boundary by sociobiology, are mechanism-based, hencecommitted to process and cause and effect. In contrast, much of the socialsciences and all humanities are meaning-based, devoted primarily to symbolismand history. The two cultures meet in human sociobiology, with often puzzlingresults.

We will argue here that human sociobiology is best developed along themiddle way, as a compound enterprise, trying to explain meaning as theoutcome of mechanism-based (and meaning-responsive) causation (Lumsdenand Wilson 1981; Lumsden 1986, 1989a). Culture, to put the matter as suc-cinctly as possible, is biological. Its elements are produced by individualcognition, which has a biological basis. It follows that the most effective way to

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study culture is across all levels of organization from gene to society, passingrepetitively through cycles of reduction and synthesis in the manner of thenatural sciences. Success in the venture is favored by the natural tendency ofsemantic memory (memory based on words and other symbols) and culture tooccur in discrete units arranged in hierarchies. This outstanding feature appearsto have escaped the attention of many scholars in the field, and certainlydeserves careful study. But first, it will be useful to make a few general observa-tions about reduction and synthesis.

WHY REDUCTIONISM WORKS

Reduction is sometimes described as the procedure whereby the experimentallaws and theory of a so-called "secondary" discipline are shown to be the logicalconsequences of the theoretical assumptions of a "primary" discipline (Nagel1961). This characterization is useful but incomplete, and potentially damagingto a productive dialogue between sociobiology and the humanities. Thenomenclature of "primary" and "secondary" is particularly unfortunate. It shouldnot be read, we suggest, as implying a pre-emptive claim of intellectual priorityor value, but rather as a descriptive assertion. The "primary" discipline istypically the subject first encountered upon moving up through the levels ofnatural organization from smaller to larger and more complex systems andinteractions (molecule, cell, tissue, organism, group, and so on). A disciplinefinds itself "secondary" to a "primary" discipline when someone notices that thesystems and interactions referred to in the theories of the "primary" disciplineare meaningful units or building blocks of the structures and processes dealtwith in the "secondary" discipline. Assignment of terms like "meaningful" is,undeniably, an evaluative act performed in the midst of debates about the truebasis of understanding in the arts and sciences. But it is not in itself adeclamatory act reserving epistemic priority solely for the "primary" discipline.All contributing subjects are potentially significant, and it is easy to see why:while King Lear is a system of interrelated words, to note that it is aShakespearean tragedy is to observe succinctly something essential about thissystem of words at its highest level of organization and significance. Althoughwe have never seen it done, we can anticipate that any adequate psycholinguisticunpacking of King Lear would, by comparison, be very lengthy, cumbersome,and more than moderately opaque. So to the extent we use the terms "primary"and "secondary" at all here (and given their historical entrenchment they are atpresent hard to avoid completely), it will be in the descriptive, rather than pre-emptive, sense.

The second point concerns interpretation versus deduction. It is certainly truethat, as Nagel pointed out, reduction involves logical consequence, throughwhich causal relations among variables are deduced in the primary discipline.But no ensuing contact with the secondary discipline is possible without a

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further, critical step involving these deductions - one of interpretation. Thededuced pattern of causal relations among variables in the primary discipline isat some point observed to be isomorphic to a pattern in the experimental lawsand theory of the secondary discipline. Laws analogous in meaning are thenobtained in the primary discipline if we interpret the appropriate combinationsof its variables in the same way we do the appropriate variables in the secondarydiscipline. It therefore takes both deduction and interpretative hypotheses tocarry out actual "reductions," and the net effect of this procedure is to align theideas of complementary subjects, not to deconstruct one field in the terms ofanother.

Thus, what we know of developmental biology conforms to the theoreticalassumptions of molecular biology (Schoener 1986; Alberts et al. 1989). Aconsensus exists among biologists that reduction is feasible across every level oforganization from ecosystems to molecules, proceeding downward in the searchfor consilience. However, the opposite thrust, from the primary discipline to thesecondary discipline, for example from molecular biology to developmentalbiology, is far more difficult, because the higher-level phenomena are generatedby interactions whose consequences are mathematically opaque beyond two orthree components. Even worse, idiosyncratic events in the history of the higher-level system may be too numerous in kind to encompass with the theoreticallanguage used for the lower-level system. Hence tissues form in response notjust to local molecular events but to the particular geometric configurations inwhich they happen to be arranged. The configurations in turn are sensitive togradients of ions, temperature, and other conditions established on the outside.That is why we speak of a residue of descriptive generalizations at the secondary(higher-level) discipline even after the theoretical principles of the primary(lower-level) discipline have been thoroughly and rigorously applied.

Holism in the loose or "soft" sense is the recognition that full descriptions of ahigher level or organization must incorporate not only theoretical assumptions ofthe lower level but also interpretive assertions along with the peculiarities ofspace, history, and signification that apply to the higher level alone. This modeof holism is nontrivial to the extent that the interactions are strong and nonlinear.Thus in the case of the fire ants just cited, the interactions of the foraging andnurse workers depend upon the recent nutritional history of the colony and theavailable food supply outside the nest. But once those circumstances are known,the interactions and the total pattern can be predicted with substantial precision.Although many such tractable cases exist, soft holists readily concede that otherinteractions (like those resonating through the textual field of a Shakespeareantragedy) may be far beyond the grasp of present theory and method.

Holism in the strict, "hard" sense is far more problematic. It is the belief thatprocesses exist which in principle are not obedient to the theoretical constructsof any primary discipline. Moreover this incongruity is so great as to require anepistemological or even ontological independence from the primary discipline:the subject must be made to fly on its own. In the hard version of holism

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emergence is subject to a fundamentally different style, language, and verifica-tion criterion. The hard version of holism goes so far as to deny the value of theof the reductionist program in many cases.

It is fair to say that the vast majority of contemporary biologists are reduc-tionists, or more precisely epistemological reductionists. In other words, theybelieve that the most robust generalizations of secondary disciplines in thebiological sciences can be aligned with the strongest generalizations of thecontiguous primary disciplines (Ayala 1974; Dawkins 1988). They are not,however, extreme reductionists. In spite of occasional triumphant speeches by afew molecular biologists, almost no one really believes that the generalizationsabout one level of organization can explain everything about the level above, orthat everything in the level above always needs to be expressed in the languageof the level below. At the same time the vast majority of biologists are softholists. They incorporate history, space, and idiosyncrasy, and they accept theinevitability of residues of descriptions that for technical reasons may never bedecomposable into the generalizations of the primary disciplines.

Most biologists consider a skillful play of methodological reductionsism andsoft holism to be the royal road to successful research. They try to pass theirsubject through a repetitive spiral of reduction and synthesis, finessing theresidue until the next round of analysis. This means that a phenomenology ornatural history is accumulated, and as soon as possible thereafter the informationis aligned with the discipline at the next level down. Colonies are analyzed asaggregates of individuals, organisms as aggregates of cells, and so forth. Thenthe processes revealed by these studies are reformulated in an attempt to alignthem with the generalizations, made at the original, higher level. The success ofthe enterprise is judged by the precision of this retrodiction and the number ofgeneralizations that can be aligned.

The ideal synthesis is one in which a small number of tight formulations at thelower level unlock into a large number of tight generalizations at the higherlevel, some of which were unexpected and subsequently verified. For example,it is now understood that juvenile hormone in insects retards differentiation ofinsect tissues at the time of cell division and molting, thus inhibiting themetamorphosis from the larval stage to the adult stage while permittingcontinued growth. This process, which is understood in part on down to the next,molecular level, has ramifications across a wide range of higher phenomena atthe organismic and social level. To return to the ants (in particular the genusPheidole, on which most research has been done), it explains neatly why someindividuals metamorphose late and have time to turn into big soldiers. If historyand special circumstances are added, still more of the colony-level pattern isexplained. When there are many soldiers, a pheromone they secrete makeslarvae less sensitive to juvenile hormone. As a result the larvae metamorphoseearly and turn into small "minor" workers, reducing the proportion of soldiers.Conversely when few soldiers are present, not enough pheromone exists toreduce sensitivity to juvenile hormone, hence more larvae grow to a larger size,increasing the proportion of soldiers. The result of the juvenile-hormone

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feedback loop is the equilibration of the proportion of soldiers (Wheeler 1986) ata level specific to particular species of Pheidole and even to colonies belongingto the same species (Johnston and Wilson 1985).

The reduction-synthesis cycle is a natural procedure, for two reasons. First,discrete units and hierarchies are probably an inevitable result of evolution bynatural selection. A hierarchy is a system in which units belonging to one set (asubassembly) interact more closely with one another than they do with units inother subassemblies at the same level of organization. The three contiguouslevels of the hierarchy are the unit, the subassembly, and the total assembly. Inthe example of the fire ants, the levels are represented respectively by a nurseworker, the caste comprising all nurse workers, and the colony comprising thenurses plus all other castes. As Herbert Simon (1981) pointed out, a complete,working assembly of interacting parts can be made much faster if the subas-semblies are first finished and put aside. The chance of error and interimbreakdown of the entire system is far greater if the assembly has to be completedas a whole, say from A to Z, than if subassemblies A-C, D-F, and so forth caneach be produced independently and then fitted together hierarchically. Supposethat component F failed on one occasion. In the unbreakable holistic system theprocess would have to be started again at A, but in the hierarchical system itneed only start at D.

This basic rule of assembly has important implications in biology. In anorganism trying to build an organ, the rate of production is accelerated by usingcells instead of a wholly interdependent syncytium. In a colony of insects, thecollecting and processing of food is more efficient if the labor is conductedpiecemeal in parallel series of workers rather than in toto by workers all tryingto act in close concert. Furthermore, as Oster and Wilson (1978) showed, it isbetter to have the workers transferable from one labor sequence to another(series-parallel) than locked into one series (parallel series). In other words, theunits should be interchangeable - and they are. It follows that evolution will alsoproceed faster with units and hierarchies. In the elaboration of a structure ofprocess by genetic change through time, selection will favor more efficientlyoperating systems. And even if complete connectivity were the better tactic in aparticular case, it might take too long to evolve. Alleles are likely to be sub-stituted more quickly if they affect a small component of the system rather thatthe entire system.

To come now to human sociobiology, reduction and hierarchy formation asconceptions are also natural because of the way the human mind works(Wickelgren 1979; Lumsden and Wilson 1981; Minsky 1985; Lumsden 1989a,b). People break sensory impressions into units even when the variation in theimpinging stimuli is continuous. In some cases, such as the basic colors, thefragmentation begins at the level of sensory screening and early corticalprocessing (Lumsden 1985; Nathans et al. 1986). In other cases, it occurs as aclassification procedure in the higher integrative centers. People may actuallysee arrays of variable objects as fuzzy sets, but they utilize prototypic images toplace and label each object in turn (Green 1983). When information is retrieved

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from long-term into short-term semantic memory, it is brought out in discrete"nodes" which are linked to other nodes in node-link structures: thus black-dog-running (Wickelgren 1979). The node-link structures are stacked hierarchicallyto recall and transmit increasingly complex information.

SOCIOBIOLOGY IN THE REDUCTION-SYNTHESIS CYCLE

The last vestiges of vitalism were eliminated with the advent of molecularbiology. It is now possible in principle to visualize a cascade of causes andeffects across all the levels of biological organization from molecule to ecosys-tem, even though a full, explicit description is far from realized in any particularcase. Sociobiology is part of that enterprise. It is not at all controversial to passfrom individual animals to animal societies. However, when we try to step upfrom individual human beings to human societies and culture, we encounter amajor difficulty. Many writers have expressed the opinion that the attempt toplace cultural behavior in biology's explanatory cascade must fail. A discon-tinuity exists, they think, between biological reasoning and reasoning abouthuman behavior. In this hard version of holism, the mind is considered toosubtle, too productive, and too evanescent for its products to be mapped ontobiological processes. Even a softer version of holism offered by critics isdaunting: The variables are too numerous, the possibility space too close toinfinite to make the program practicable. And (the argument continues) even ifsuch mapping were theoretically possible, culture itself is partly a product ofhistorical accident, and history cannot be captured in the network of causalexplanations in the mode of the natural sciences. Therefore reduction, howeversuccessful it proves in the biological sciences (including animal sociobiology),cannot be employed to bridge biology and the social sciences.

This pessimistic view may be correct. However, the only way to find out is tokeep trying to do what the critics say cannot be done or at least requires aHerculean effort. In previous work (e.g., Lumsden and Wilson 1981, 1983,1985; Lumsden 1989b), we have suggested the means for such an analysis. Wehave shown that meaning-based explanations of human behavior can be directlyincorporated into the cause-effect schemes of population genetics by interposingpostulates, such as those expressible in semantic network theory about thegrowth and function in mental representations. Culture is usually studied at thesurface, holistically and in great detail for its own sake. But it is underlain bymind and its basis in semantic memory. Semantic memory can in turn be at leastpartially understood in terms of units that the brain stacks into hierarchies. Thereis as yet no reason to believe that in their evolution the semantic order of themind and hence culture bypassed the advantages of hierarchical design longsince discovered by ordinary biological systems. If this is indeed the case, thenfurther research will continue to substantiate the hypothesis that culture can bediscussed in terms of natural units and productively treated with ideas firstapplied to biological pattern and order.

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When compared one to another, cultures have two qualities that can beanalyzed at the outermost level: central tendencies and diversity. Thewidespread practice of initiation rites is a central tendency; its variation in formand occasional absence among societies constitutes the diversity around theprevailing thrust. When central tendencies are strong and diversity limited, amore favorable opportunity exists for reduction to the next level down, that is, toindividual cognition and semantic memory. Examples include facial expres-sions, color vocabularies, incest taboos, and idiograph formation. To takeadvantage of this entr6e it is useful to remember that human beings exist in aprimarily cultural environment. They are also aware of only a fraction (inindustrial societies, only a minute fraction) of the content of their culture. Ineach category of behavior they face choices. Some occur only a few times in alifetime, such as the rites of passage, others every few minutes or seconds, suchas the choice of words and postures. If the cultural alternatives can be expressedin terms of the units of semantic memory, the node-link structures, then it willfollow that people are choosing between units and hierarchically arrangedcompounds of semantic memory. For analytic convenience the shift from onechoice to the next at each decision point can be treated as probabilistic in nature.New choices may be added by invention or importation from other cultures(Findlay and Lumsden 1988). The beliefs and practices of a person can bemeasured as transition rates among the alternative semantic structures. But thereis more. People are not shifting back and forth in a vacuum. Rather theirtransition rates (between alternatives a and b, say) are influenced to some degreeby what choices others have made around them. In some cultural categories,such as the avoidance of brother-sister incest, they are relatively insensitive. Inothers, such as body ornamentation and language, they are extremely sensitive.It is possible to write empirical functions relating the transition rates to theprevalence of usage by other members of the society. When this is done, thecrucial theoretical assumptions are obtained at the level of individual behavior,at least for the simplest cases. The assumptions pertain to the relationship of realcognitive processes that can be measured and would be intrinsically interestingeven in the absence of further theoretical advance.

So now there exists an observed set of phenomena at the level of culturaltrends and diversity at the level of societies, as well as a picture of the contribut-ing processes at the next major level down, of individual cognition. Withappropriate mathematical techniques (Lumsden and Wilson 1981), theproperties of individual cognition can be used to derive the cultural trend and abaseline pattern of cultural diversity.

Biologists and social scientists often differ strikingly in their approaches tohuman social behavior - not only in emphasis on mechanism versus meaningbut also in the scale of time over which the analysis takes place. Biologists tendto look for common, species-specific features and thus to stress central ten-dencies. They like to emphasize genetic history as opposed to cultural history, inother words the full two million years or more of human lineage in whichgenetic evolution took place, whereas social scientists and humanists usually

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(but not always) prefer to emphasize diversity among persons and cultures andto look for the causation in relatively very recent cultural, nonbiological history.These two perspectives may at first appear incompatible, but they simplyencompass different time scales and can be made part of a single pattern ofexplanation.

To summarize the argument of the this section, human sociobiology isfeasible, and can incorporate culture, if we pass back and forth in an analysis-synthesis cycle through levels of organization and across a time scale longenough to encompass substantial genetic change. There appears to be no genuineepistemological barrier to proceeding in such a manner.

ARE SOME PHENOMENA BEYOND THE REACH OF NATURAL SCIENCE?

Of course, to return to commonly heard critiques of the sociobiological ap-proach, there is still more to the understanding of culture than the interpretationof central tendency and the statistical derivation of cultural diversity. There iscomplexity and particularity so great as seemingly to fall wholly outside scienceand hence by default remain wholly within the domain of the humanities.Consider, with Nelson Goodman (1968), the temperature chart of a hospitalpatient versus the calligraphic brush stroke of a Japanese landscape painter. Inboth instances the curve C- tracing body heat on one hand and the mountain'sprofile on the other - is, for the sake of this argument, the same. But that of thetemperature chart, by virtue of its social context, conveys only one kind ofinformation. We focus exclusively on the vertical displacements encoded in therise and fall of Cto monitor the patient's condition. Embodied as a landscape, Cis radically different in its impact. Its many nuances of pigment density, line,and texture draw our attention. The meaning of one single such expression in artand language can be the subject of analysis orders of magnitude richer than thereading of the temperature chart.

But does this mean that C- as landscape - lies outside human sociobiologyand hence is immune to levels-of-organization analysis? Not at all. It is useful torecognize that the painterly C remains a symbol in a symbol system, different inkind from the temperature chart but available still to reflective analysis. It can beteased into contributing nuances, linked into history. The individual taste andjudgement that went into its creation, and the individual taste and judgementused to decipher it, are parts of the semantic network interposed between geneand culture. The painterly C is subject in successive steps to a cognitive psychol-ogy of esthetics, a neurobiology of cognition, and a theory of the evolution ofnervous and sensory systems. This succession brings, we believe, an accretion ofsignificance via a reduction to an essence that belongs to no one discipline. Thusa reductionistic program of this kind does not diminish the object it analyzes. Onthe contrary, it make possible a new and richer holism, one in which the totalpattern is both grasped and reconstituted intuitively from a knowledge of itsparts. The new holism ranges up and down the levels of organization in a more

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precise, factual manner to blend analysis and synthesis. An upward journeythrough the spiral of analysis and synthesis, holism brings reduction to fulfill-ment. By embracing diversity it joins many truths into one vision of the world'sessential unity.

ACKNOWLEDGEMENT

We are grateful to Andreas Steigen for a fruitful discussion of the concept ofresidue in holistic reconstruction.

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Lumsden, C. J.: 1986, 'The Gene and the Sign', Semiotica 62, 191-206.Lumsden, C. J.: 1989a, 'The Gene's Tale', Biology and Philosophy 4, 495-502.Lumsden, C. J.: 1989b, 'Does Culture Need Genes?', Ethology and Sociobiology 10,

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holism and reduction in sociobiology - lessons from the ants and human culture (1991) by edward...

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