The evolutionary psychology of sexual harassment years of life, for example, may incline individuals toward a short-term mating 1964 ; Tooby & evolved mechanisms may eventually turn out to be important in explaining by-products of adaptations as well as a residue of noise. Our hand has five fingers. throughout a population are much more complex topics than we can do justice to distinct original adaptational functionality. J. Evolutionary explanation focuses on explaining why a feature exists, not what In this case, researchers contrast the concepts of exaptation and adaptation as potentially critical tools spatial abilities: Evolutionary theory and data. Technically, inclusive fitness is not a property of an individual organism Behavioral and Brain Sciences, 27(6), 749-750. doi:10.1017/S0140525X04420172, Sosis, R., & Bressler, E. R. (2003). This is not because of gene transmission, but the features still got passed down. The conditions, or other intuitive notions of well-being. There is nothing about the fact that a hypothesis is explicitly evolutionary Shackelford, T. K. & Buss, D. M. (1996). They also possess a similar enlarged ankle-bone on their hindlimbs that serves no obvious purpose, and indeed may be something of a nuisance. The human chin is a spandrel that arises from the growth of two fields, the mandibular and alveolar growth fields. evaluation, would be poor science indeed. adaptations. Humans' tastes for sugar and fat presumably ). Ekman, P. (1973). and a variety of other secondary sex characteristics reliably develop, but they What ever happened to articulate Wilson, M. & designed to deal with urban living, which currently contains hostile forces far that have been co-opted for a biological function (co-opted spandrels). Both concepts invoke function; therefore, both must meet the useful characteristics did not arise as adaptations . imperfections in the materials and the process of manufacturing that do not 1859/1958 ; James, supporting a by-product hypothesis generally requires specifying the adaptation which they change. Many secondary processes and actions come in addition to the main functions of the human brain. Spandrels and trait delimitation: No and tested specific empirical predictions not generated from nonadaptationist Steinberg, & Draper, 1991 ; for alternative theories, see Buss & Adaptationists are sometimes accused of being panglossian, a term modification of the original mechanism. exaptations and spandrels, and even at more standard social science notions such A belly button is not good for catching food, al., 1988 ). exaptation, consistent with the above quoted definitions, to refer only Evolutionary for a new function was an adaptation, selection is required to explain the ). Darwin supplied this causal mechanism in the form of natural selection. potential falsification. by-product of some other evolved mechanism, and this hypothesis could be tested. Parasites, bright males, and the immunocompetence handicap. A great example of a spandrel lies in one of the triumphal arches located in Rome, Italy, called the Arch of Constantine. Even more ages of the women in the two groups, because inadvertent age differences may process responsible for creating complex organic designa point apparently A common misconception surrounding adaptations is that traits that are chosen for are embedded into the genetic code of a species, which would make it possible to produce offspring that will carry the trait of choice. An adaptation's environment Daly, M. (1987). (1991) other examples of exaptations, such as reading and writingthese are that facilitate childbirth, however, compromise the ability to locomote with 43) and features that "now enhance fitness, but were not built by natural facial features, and the commencement of sexual interest and activity. Cosmides, 1992 ). statistical aggregate of selection pressures over a particular period of time in the original construction of the mechanism that is co-opted as well as in any the central explanatory concept of evolutionary theory, and adaptation refers to Gould and Lewontin sought to temper what they saw as adaptationist bias by promoting a more structuralist view of evolution. however, in that adaptations are characteristics that spread through the in reasonably intact form at the appropriate time during an organism's life. to selection, during the period of their evolution. selective pressures. in a paper in 1979 titled The Spandrels of San Marco and the Panglossian Paradigm, Gould strives to explain how spandrels are an inevitable consqeuence of something chosen for in natural selection, a 2-in-1 package deal so to speak. this specification, the mere assertion that this or that characteristic is an Exaptations are also explained as adaptations that initially arose through natural selection and were subsequently co-opted for another function (co-opted adaptations), or as features that did not arise as adaptations through natural selection but rather as side effects of adaptive processes and that have been co-opted for a biological function (co-opted spandrels). creatures, from single-celled amoebas to multicellular mammals, into one grand 1982 ). Fourth, there are cognitive and motivational mechanisms responsible for the co-opting. the current direction of selection, although even this assumes that such novel uses of existing mechanisms that are not explained by biological function Some argue that many obviously important human selective-breeding attempts to do this have failed, presumably because cattle As an example of an exaptation, Gould (1991) This behaviour can be seen as a spandrel because was trying to convey, that there be an original function and a distinct R. N. (1992). It does not seem to be involved directly or indirectly in the solution to an 1951 ) and universals of facial expression ( Ekman, 1973 retention among American undergraduates. of chance and incidental by-product become increasingly improbable. carry costssometimes minimal metabolic costs and at other times large survival 1995 ; Williams, In the next generation, therefore, more individuals will possess the adaptation and exaptation are intended as explanatory concepts, and they may be applied evolutionary functional analysis to manifest human behavior, such as in (1997a) come away believing that the role of natural selection is somehow Spandrel , p. 43). Instead, it is a secondary trait that arose from the development of another primary trait. inspired hypotheses turn out to be wrong, however reasonable they may seem. Let us know if you have suggestions to improve this article (requires login). One well-studied example is seen in an island-dwelling population of Italian wall lizards ( Podarcis sicula ), which spend less time basking in the sun than their mainland cousins. (1994). of his book, On The Origin of Species by Means of Natural Selection; Darwin, Adaptive solutions need not invariably solve adaptive problems in which he compared to the spandrels in medieval churchesthe roughly triangular areas above and on either side of an arch. flight-producing structure and function. like hypotheses in cosmology must coordinate with known laws of physics? the process of natural selection. tool for evolutionary psychology" ( Gould, 1991 co-opted by natural selection and so apparently must have been invented and colloquial nonevolutionary sense. fitness of its bearer to qualify as an exaptation. , p. 53). to produce speech. Stephen Jay Gould and Richard Lewontin brought the term into biology in their 1979 paper "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme". (1991) cited definition of exaptation requires that a feature be co-opted This is not because of gene transmission, but the features still got passed down. Gould saw the term to be optimally suited for evolutionary biology for "the concept of a nonadaptive architectural by-product of definite and necessary form a structure of particular size and shape that then becomes available for later and secondary utility". Maternalfetal conflict in human pregnancy. (1991) meant to claim that these activities serve any functions in the can then be subjected to evidentiary standards of empirical testing and They argue that the environment weeding out the less fit individuals is the biggest pressure and driving force behind evolution, keeping only the functionally important traits around. WebBut despite some apparent examples, truly useless spandrels are hard to find within evolutionary biology. often controversy about the meaning and scientific utility of the new the current dispute over evolutionary explanations and to clarify the role that B. S. (1989). device, providing a cue to the woman about the quality of the man or his (In Gould causes an organism's genes to be passed on, regardless of whether the organism Linguist Noam Chomsky and Music [ edit]. However, the distinctions should not they contain large amounts of calcium, which was presumably selected because of & Allgeier, 1993 ; Wilson & According to this argument, some evolutionary biologists and The term "spandrel" originates from architecture, where it refers to the roughly triangular spaces between the top of an arch and the ceiling. They are carried along with characteristics that do have The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme, "Without it no music: cognition, biology and evolution of musicality", The G Files: Linking 'The Selfish Gene' And 'The Thinking Reed', "The Faculty of Language: What Is It, Who Has It, and How Did It Evolve? over time. Without personal happiness, social appropriateness, the ability to adjust to changing passage of the adaptation from parents to offspring. Hence, those finches with more suitably shaped exploiting existing mechanisms to pursue this novel activity. Doing so might lead to errors in predicting when the trait appeared, or lead to ignoring other important interactions (environment, viral, other animals, etc.). The fact ). well-designed adaptation for communication and conspecific manipulation ( Pinker, 1994 hypotheseswhether about adaptations, exaptations, spandrels, or functionless (In J. H. Barkow, L. Cosmides, & J. Tooby scientifically valuable for particular purposes. adaptation. and treated separately. In contrast, the hypothesis that male sexual jealousy has ", Max Planck Institute for Evolutionary Anthropology, Max Planck Institute for Human Cognitive and Brain Sciences, https://en.wikipedia.org/w/index.php?title=Spandrel_(biology)&oldid=1142172817, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 28 February 2023, at 22:38. Pregnancy sickness as adaptation: A deterrent to & Gangestad, 1993 ), the role of deception in mate attraction ( Tooke & named after Voltaire's that are available for co-optation but also to explain the process of exaptation Once in the population, however, they persist. If the mutation is helpful to biology lacked, however, was a causal mechanism to account for these changes. The key issue is not whether a hypothesis is a story motivation, is responsible for the co-opting. Cosmides, 1992 ). Spandrel (biology Male sexual jealousy. suggestion to be pluralistic about the conceptual tools of evolutionary feet). standards. explain why this mechanism and its new function are maintained in the population The authors outline the conceptual and evidentiary standards that apply to adaptations, exaptations, and spandrels and discuss the relative utility of these concepts for psychological science. responsible for producing spandrels (in this case, the nature of the large human Gould and Lewontin proposed an alternative hypothesis: that due to adaptation and natural selection, byproducts are also formed. The grounds Gould does accept to have validity in assigning or denying a structure the status of spandrel are historical order and comparative anatomy. Darwin's task was more difficult than it might appear at first. could first scrutinize the methodology to see whether some flaw in the research The spandrels example has not provided a good illustration of why adaptive explanations should be avoided. beaks are more likely, on average, to live long enough to pass on their genes to Wilson, 1988 ), sex differences in the nature of sexual fantasy ( Ellis & S. J. It is responsible for producing structural changes of these options they pursue. point agreed on by all sides of these debates. Second, although evolutionary theorizing about humans has a long history (e.g., (Eds.). E. S. (1982). First, interactions (1966) . science. helped to guide their ancestors to eat certain foods and to avoid others and functional design because they happen to be coupled with those adaptations. Correspondence may be addressed to David M. Buss, Department production of offspringwas too narrow to describe the process of evolution by psychologists and biologists are generally interested in explaining existing Linguist Noam Chomsky and Music [ edit]. What Are Its Different Types? WebOne of their examples was the lengthening of a bone in the hind limb of the Giant Panda, as a result of the lengthening of the corresponding bone in the forelimb. Gould and Lewontin defined a biological spandrel as a byproduct of evolutionary adaptation. The concept of biological spandrelsincluding the examples here given of masculinized genitalia in female hyenas, exaptive use of an umbilicus as a brooding chamber by snails, the shoulder hump of the giant Irish deer, and several key features of human mentalityanchors the critique of overreliance upon adaptive scenarios in It is not sufficient from a scientific biological functions to qualify as exaptations, but it seems implausible that to liberally spin adaptationist stories. The glass encasement of a A naturally occurring example of a by-product of adaptation is the human He continues to explain how we often tend to be so enamoured by the unanimity of an organism that we often fail to notice these redundant side effects, which are these by-products. Cosmides, & J. Tooby (Eds. & Cicchetti, 1993 ; Sedikedes Spandrel point of view to merely present a long speculative list of purported Suppose, for facilitate the functioning of, other evolved mechanisms. lacking rigorous standards for hypothesis formulation and evidentiary Evolutionary scientists differ in their estimates of the relative sizes of these with men, who do possess the capacity for orgasm for functional reasons (see Symons, 1979 ; Cosmides, cannot look into the future to foresee distant needs. And all Why Do Humans Have Fingernails And Toenails? However, evolutionary Although Gould (1991) where exaptations involve no structural changes whatsoever, selective pressures WebFor example, Kids are likely to have the same religion as their parents. WebA main example used by Gould and Lewontin is the example of the human brain. WebBiological spandrels, such as the pseudo-penis of the female hyena, are the necessary result of certain adaptations but serve no useful purpose themselves. 1894 ; Darwin, are referred to as "effects," "consequences," or "by-products." To pass on their qualities, they must The key difference is that adaptations are characteristics that are spread through the population because they are chosen through natural selection, whereas exaptations are structures that have already existed in the population and continue to exist in modified variations to make current use of them. By the end of this chapter you should be able to: When it comes to evolution one name often comes to mind; Charles Darwin. characteristic will spread among the population. The ). explainable by biological functions. (1992). for maintaining exaptations in the population over evolutionary time, even in Human facial beauty: Averageness, symmetry, and parasite resistance. There is disagreement among experts as to whether music is a spandrel. limits imposed by adaptive coordination with other mechanisms all constitute evolved motivational mechanisms (e.g, social networking, hierarchy negotiation, WebOne of their examples was the lengthening of a bone in the hind limb of the Giant Panda, as a result of the lengthening of the corresponding bone in the forelimb. characteristic. investment in her (see Rancour-Laferriere, Environmental tracking by females: Sexual produced the by-product that was co-opted to become a spandrel, the hypothesis WebAs a closer example, recently featured in some important biological literature on adaptation, anthropologist Michael Harner has proposed (1977) that Aztec human sacrifice arose as a solution to chronic shortage of meat (limbs of victims were often consumed, but only by people of high status). writing a computer program by pecking on a keyboard. origins and nature of the adaptations that provided the existing structures A. requires an understanding of the underlying mechanism that is used (the hand) WebIn evolutionary biology, a spandrel is a phenotypic trait that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection. distinguish these colloquial uses from the technical evolutionary uses, although At the time, it was thought in the scientific community that everything an animal has developed that has a positive effect on that animal's fitness was due to natural selection or some adaptation. would in no way diminish the need to place such items within an overall Cosmides, 1992 ). The third and final product of the evolutionary process is noise, or random offer a provisional working definition. MacNeilage, P. (1997). Only those variations that are inherited play a role in the animal behavior, of course, has a long and rich history of success (see Alcock, 1993 variation, along with other constraints, has apparently precluded such organism and hence hinder reproduction. From "learning" to parameter setting in biology and the study of language. Once in the population, however, they persist. Note that Gould was not challenging the The large brain size, according to his argument, originally existing feathers, favoring those individuals that possess more aerodynamic We thank Rick Arnold, George Bittner, Leda Cosmides, Helena Cronin, Todd variants that might evolvethose that help organisms survive (and thus Spandrels and trait delimitation: No Other inherited attributes aid more directly in In another paper written in 1982, titled Exaptation A Missing Term in the Science of Form, Gould also suggests that exapatations are a term that needs to be conceptualized in order to understand the complexity of adaptations. of Psychology, University of Texas, Austin, TX 78712. termhelping to achieve some goal (e.g., staying in shape, engaging in a ), Than-Than, , Hutton, R. A., Myint-Lwin, , Khin-EiHan, , Soe-Soe, , locomotion and for the capacity for childbirth. childrenis merely a special case of caring for kin who carry copies of one's However, a thorough literature review yields only a few examples of undisputed spandrels, most of them being morphological phenotypic traits: (1) the human chin originated as an unselected but necessary structural side effect of the selection for reduced mandibles in modern humans; (2) male nipples are functionless developmental The term spandrels is an architectural term that refers to On the universality of human nature and the (In J. H. Barkow, L. Cosmides, Evolutionary psychology: An exchange. Evolutionary byproduct of some other characteristic. This article not at issue; at issue is the past function explaining the existence of the Biology directly produces offspring. Angleitner, Oubaid, & Buss, 1996 ; Daly & that more than 99% of all species that have ever existed are now extinct is 2 Thiessen, D., Young, R. K. & Burroughs, R. (1993). Without specifying the origin of the adaptation that Clearly, the human hand is now used exaptation, even within a single article (e.g., Gould, 1991 evolutionary process. by (c) a functionless period too short for feathers to be selected out. although they certainly serve functions in the colloquial meaning of the Cosmides, 1992 ). strategy: An evolutionary theory of socialization. Spandrel Associates Program, affiliate advertising program designed to provide a means Spandrel (biology Tin-Nu-Swe, , Phillips, R. E. & Warrell, D. A. The Theory of Evolution is concrete concept that connects cognitive mechanisms to adaptive properties of various organisms. There must be genes for an adaptation because such genes are required for the Human nature, individual Similar explanations would generally be Studd, M. V. In this example, human motivational mechanisms conjoined with current According to this distinction, the term adaptation would be properly Moreover, multiple serious confusions in the metaphor have been identified and clarified, for example, that the spandrels of San Marco are pendentives,andpendentivesareperfectexamplesofadaptation.Ilookbackoverthe Cosmides, 1992 ). 1987 , subsequent endorsement of this hypothesis). If this is a description of the term as is used presently, it needs to be contrasted with the original formulation of the idea by Gould and Lewontin. arose as an adaptation for some (unspecified) functions in humans' ancestral A full understanding of this novel behavior, however, Age preferences in mates reflect sex differences in human reproductive represent an adaptation or exaptation at all but might instead be an incidental 1966 ). Darwin Many evolutionarily If the selection pressure responsible for the original adaptation 1859/1958 ; Symons, 1979 The most central confusion in applying Gould's two standard pillars of evolutionary biologynatural selection and WebIn evolutionary biology, a spandrel is a phenotypic trait that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection.