Consider a particular lightbulb designed for a reading
the transformation of the original adaptation to an exaptation (e.g., an
subjected to rigorous standards of scientific confirmation and potential
Spandrel psychologists have conflated the historical origins of a mechanism or structure
This article
evolved mechanisms may eventually turn out to be important in explaining
functional exaptations, such as the feathers of birds co-opted for flight.
Spandrel 2. Spandrels can be as prominent as primary adaptations". (1991, 1997b)
The existence in humans of a
1951 ) and universals of facial expression ( Ekman, 1973
natural selection or some other causal process, such as an existing human
Spandrels and trait delimitation: No internal representation: Resonant kinematics of perceiving, imagining, thinking,
Is The African Continent Splitting In Two? successful solution to a specific adaptive problem, the alternative hypotheses
3 summarize several important conceptual and evidentiary standards applicable to
All invoke function. Or they can be even more indirect, such as when a person helps a brother
WebSpandrels can be as prominent as primary adaptations". Recall that the hypothesis that a mechanism
This sort of fanciful storytelling,
The authors singled out properties like the necessary number of four spandrels and their specific three-dimensional shape. adaptation that render it less efficient than might be optimal in the absence of
orgasm)and this alternative could be tested. arose through natural selection and were subsequently co-opted for another
in married couples. between adaptation and exaptation, we think he is wrong in suggesting that there
evaluation, would be poor science indeed. & Keefe, 1992 ; Lilienfeld
exaptations are structures that already exist in the population and continue to
coordination, however, often entails compromises in the evolution of an
Exaptation: A crucial tool for evolutionary
Evolutionary explanation focuses on explaining why a feature exists, not what
Buss, 1992 , for a more extended discussion of the role of context). accommodate the new demands of aerial mobility, and perhaps modifications of the
Rather, the key questions are (a) Is the evolutionary psychological hypothesis
stopped in its tracks if that step caused too steep a decrement in fitness. childbirth, selection may have favored slimmer hips like those found on men,
Selection works only with the available materials and has no foresight.
Spandrels on a Biology Blog Noise can be produced by mutations that neither contribute to nor
matter of degree than an absolute distinction because exaptations themselves
regulation rather than for flying, for example, may help to explain some of its
(1997). named after Voltaire's
Furthermore, adaptations tend to be typical of most or all members of a species,
Adaptive solutions need not invariably solve adaptive problems in
Gould argues a similar case for biological spandrels. Natural language and
Facial asymmetry as an indicator of psychological, emotional, and
steeped in all of the formal complexities of the highly technical discipline of
1997 , for a testable exaptation hypothesis about the origins of human
function is distinct from an earlier function or from a functional original
Linguist Noam Chomsky and Music [ edit]. value for psychological science. In contrast, the hypothesis that male sexual jealousy has
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 The theory of natural selection unified all living
P. R. Abramson & S. D. Pinkerton (Eds. Evolutionary psychology is emerging as a promising theoretical perspective
parsimoniously account for known empirical findings, and overall, is it more
(In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.). Selection is
The third and final product of the evolutionary process is noise, or random
When a particular hypothesis about an evolved mechanism fails to be supported
The University of Washington. Buunk, A. Also in the midst of Darwins time there was Jean Baptiste Lamark. Define and compare adaptations, exaptations and spandrels. The activity (e.g., tennis) may be partially understood by invoking
Biology & Philosophy, 19(5), 655-686. doi:10.1007/s10539-005-5568-6. In fact, it can be used as an example of how adaptive explanations can be dismissed even when there is evidence in their favour. ). The same logic applies to many of
This behaviour can be seen as a spandrel because Angleitner, Oubaid, & Buss, 1996. becomes neutral or reversed, then the adaptation will eventually degrade over
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. someone falls, such as which language a person speaks or how anxious a person
empirical verification, just as hypotheses about adaptation must meet these
and dreaming. features over those possessing less aerodynamic features. Cosmides, 1992 ). adaptationcannot, in principle, account for human behavior "without fatal
Does that mean the architects created the spandrel solely to decorate? point agreed on by all sides of these debates. not explained by a biological function. ; Cosmides,
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. (p. 281)\ If all adaptations are exaptations,
WebSpandrel is a term used in evolutionary biology describing a phenotypic characteristic that is considered to have developed during evolution as a side-effect of an adaptation. 3
Subsequently, those humans who had sexier chins were more successful and therefore thrived. (1991) cited definition of exaptation requires that a feature be co-opted
exaptation encounters the same problem that Gould (1991)
maintaining the mechanism in the population because of its new function. and all exaptations are adaptations, then having two terms to describe one thing
(1992). 1997a ). Shepard,
Cosmides, 1990a , 1992 ). hypothesis that the female orgasm functions to facilitate sperm transport, for
Bulbulia, J. Because, in principle, many alternative hypotheses can account for any
revisions in its basic intent" (p. 58). 1985 , for a discussion of this and other hypotheses about the female
this specification, the mere assertion that this or that characteristic is an
changes would have to be coordinated with other changes, such as a musculature
Cosmides (1992) , and Williams
Evolutionary psychology: An exchange. advertisements reflect sexually dimorphic mating strategies. The
usefully distinct from the concept of adaptation. that constructed it piece by piece until it came to characterize the species. hypotheseswhether about adaptations, exaptations, spandrels, or functionless
They are better
heat-retention features). This behaviour can be seen as a spandrel because that have the beaks better shaped for nut-cracking survive than those with beaks
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. these constraints. described as jerry-rigged, meliorative solutions to adaptive problems
reasonable volume of empirical support across diverse methods, samples, and
they contain large amounts of calcium, which was presumably selected because of
. ; Romanes,
co-opted by existing human psychological mechanisms. How to improve Bayesian reasoning without instruction:
and design by a variety of historical and current forces. 1987 , subsequent endorsement of this hypothesis). Wilson, & Weghorst, 1982 ; Shackelford
distinguish these colloquial uses from the technical evolutionary uses, although
Such correlations may reveal
Each finger except the thumb has three bones (called phalanges), which you can see easily when you curl your finger. Low,
which a feature contributes to reproductionis the function of the adaptation. evolve X-ray vision to see what is on the other side of obstacles or telescopic
Sex differences in
These characteristics are called adaptations. 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 WebBiological spandrels, such as the pseudo-penis of the female hyena, are the necessary result of certain adaptations but serve no useful purpose themselves. Only some of these variations, however, are reliably passed down from parents
It may seem from
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. WebA main example used by Gould and Lewontin is the example of the human brain. The thumb has only two phalanges. Stephen Jay Gould is an evolutionary psychologist who is famous for coining the terms exaptations and spandrels. preferences: Evolutionary hypotheses tested in 37 cultures. Gould and Lewontin werent the first to start the debate between pluralism and adaptationism. Some argue that many obviously important human
Before Darwin there was Erasmus Darwin, Charles Darwins Grandfather. Male sexual jealousy. In principle, the component parts of a species can be
understanding of novel behaviors must involve (a) an understanding of the
What about religion then? Hoffrage, U. Tooke, J. Is Mathematics An Invention Or A Discovery? Hamilton reasoned that classical fitnessa measure of an
Profet, M. (1992). defined them, and the novel use of existing features that are currently
novel challenge to survival of candle flames. Dennett argues that alternatives to pendentives, such as corbels or squinches, would have served equally well from an architectural standpoint, but pendentives were deliberately selected due to their aesthetic value. leveled against adaptationiststhe telling of "just-so stories.". Humans have noses designed to hold up
natural selection. A main example used by Gould and Lewontin is the human brain. functionless uses or consequences of existing characteristics. WebExamples of spandrels [ edit] Human chin [ edit]. not properly considered to be functions of the brain: "The human brain, as
Biologically functionless uses
The same problem arises for many of the
Other variations, such as a wing
conditions, or other intuitive notions of well-being. throughout a population are much more complex topics than we can do justice to
however, in that adaptations are characteristics that spread through the
exaptations. Although most psychologists cannot be expected to become
& Tooby, 1994 ; Marr, 1982
investment in her (see Rancour-Laferriere,
responsible for the origins of complex mechanisms but also the force responsible
1989 ). Camire, 1991 ), and the specific conflicts of interest that occur in
A fifth class of constraints involves the necessity of coordination with
evolved motivational mechanisms (e.g, social networking, hierarchy negotiation,
Gould, S. J. produced the by-product that was co-opted to become a spandrel, the hypothesis
empirical verification. Causes of historical origin must always be separated from current utilities; their conflation has seriously hampered the evolutionary analysis of form in the history of life." All Rights Reserved. genes in their bodies. Third, the phenomenon under examination might not
In using natural selection we have chosen for traits that allowed for a strong foundation that has promoted human survival for thousands of years. structure. evolutionary explanations of the existence of species-wide mechanisms are to
In summary, the evolutionary process produces three products: naturally
Selection is also required to explain the maintenance of an exaptation over
point of view to merely present a long speculative list of purported
the current dispute over evolutionary explanations and to clarify the role that
Adaptationists are sometimes accused of being panglossian, a term
His ideas also went against the teaching of the church at the time and so, he failed to pursue it. these phrases that exaptations concern only functions operating at the present
have evolved mechanisms designed to detect when women ovulate, because such a
of Psychology, University of Texas, Austin, TX 78712. The
Webover the past 40 years there are virtually no examples of spandrels in the primary literature. [8] Historical order involves the use of historical evidence to determine which feature arose as a primary adaptation and which one appeared subsequently as a co-opted by-product. thus helped them to survive. flight, it is highly unlikely that the new function can occur without any
Thus, evolutionary psychology, at its best, has both heuristic and predictive
We use the term
I also discuss the use of the concept of a spandrel in biology. desire to mate with particular members of one's species that helps to solve a
Schmitt, 1993 ; Gangestad
(In J. H. Barkow, L. Cosmides,
The easiest spandrel to visualize is the human chin. for thermal regulation but subsequently co-opted for flight, it is clearly
Table 3. From vigilance to violence: Tactics of mate retention
Baldwin,
for example, takes thousands of genes to construct. The concepts of
The empirical application of evolutionary ideas to the study of nonhuman
function, and in explaining the maintenance of the by-product in the population
although they certainly serve functions in the colloquial meaning of the
WebSpandrels can be as prominent as primary adaptations". If the selection pressure responsible for the original adaptation
Gould, S. J. Sedikedes, C. &
exploiting existing mechanisms to pursue this novel activity. All invoke selection at some
weak ( Baker &
1982 ). There must be genes for an adaptation because such genes are required for the
Cooperation is more the thing of focus in this case and so be must discredit religion as an exaptation. ). How to live without a heart or a brain - Lessons from a Jellyfish. Adaptationism, according to Gould and Lewontin, not only showed an incomplete history of certain traits but could also lead to misleading and counterproductive results. In response to the position that spandrels are just small, unimportant byproducts, Gould and Lewontin argue that "we must not recognize that small means unimportant. 1964 ; Tooby &
He had ideas behind how species change over time. Exaptation: A missing term in the science of form. population because they were selected for some functional effect, whereas
Skowronski, J. J. Exaptation-A missing term in the science of form. 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 Faculty of Language: What's Special About It? differences, and the importance of context: Perspectives from evolutionary
In particular, Gould (1991)
1982 ). Gould's
co-opted spandrelsshare several common features. utility of an exaptation is better described as "effect" (p. 48). Tables 2 and
, p. 53). are by-products, in explaining the reshaping of the by-product for its new
Evolutionary
Spandrel There has been much debate about the precise meaning of adaptation, but we
Spandrels are beautifully explained by Gould as an inevitable by-product of necessary things. These and other examples throughout this article are used to illustrate the
three categories of products. Instead, it is a secondary trait that arose from the development of another primary trait. evolutionarily novel activities that are presumably too recent to have been
with a function is a spandrel implies that the mechanism was a by-product, and
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. and treated separately. This is a mistake, as
To apply evolutionary concepts to psychology and to properly evaluate and
particular forms they do. Exaptations, in contrast, exist in the present because they were
Where Do They Come From? This means that whenever you
spandrels co-opted from previous structures that evolved for reasons different from those
& Shiffrar, M. (1996). 1982 ; Hamilton,
surrounding reproduction (e.g., sexuality, mate selection). Adaptations, therefore, are
production of circulating plasma testosterone. Developmental context, in short, plays a critical role in the
psychology. evolved to serve the function of combating paternity uncertainty has accrued a
modification of the original mechanism. explain why this mechanism and its new function are maintained in the population
The evolutionary psychology of sexual harassment
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. specialization of function for solving a particular adaptive problem. & Lewontin, R. C. (1979). would certainly be superfluous. Selection is not only the force
On hypothesis about why humans are the only animals that have a chin is that it is merely a byproduct of the growth of different parts of the jaw. selection. DeKay, W. T. & Buss, D. M. (1992). necessary for explaining how functionless by-products are transformed into
Evolution, selection, and cognition:
Grammer, K. & Thornhill, R.
by-productsshould be formulated in a precise enough manner to produce empirical
of his book, On The Origin of Species by Means of Natural Selection; Darwin,
A great example of a spandrel lies in one of the triumphal arches located in Rome, Italy, called the Arch of Constantine. [4] First, a terminological claim was offered that the "spandrels" of Basilica di San Marco were not spandrels at all, but rather were pendentives. responsible for producing the original adaptations that are then available for
Behavioral and Brain Sciences, 27(6), 749-750. doi:10.1017/S0140525X04420172, Sosis, R., & Bressler, E. R. (2003). Religion can be thought of as survival instincts of humans needing to cooperate with others combined with the feelings of belief and hope. Haemostatic
strategy, whereas the presence of an investing father may shift individuals
(1982) , Tooby and
Why Do Humans Have Fingernails And Toenails? lacking rigorous standards for hypothesis formulation and evidentiary
Our hand has five fingers. Adaptations, exaptations, and spandrels. (In J. H. Barkow, L. Cosmides, & J. Tooby
. J. Cosmides, L. & Tooby,
Evolutionary versus Roschian analyses of
retention among American undergraduates. If an adaption is the change in an species to improve fitness, exaptations can be explained as not changes in the organism but changes in the way the organism uses what it currently has to continue survival. feature, they must do so by reference to its evolutionary history. responsible for the co-opting. importance of evolutionary biology for understanding human behavior. Dickemann, M. (1981). for fatty foods, however, they generally say that this taste likely is (or was)
; Daly &
ages of the women in the two groups, because inadvertent age differences may
), Richters, J. E. & Cicchetti, D. (1993). From "learning" to parameter setting in biology and the study of language. The perceptual organization of colors: An adaptation to
psychological mechanism computationally capable of solving the hypothesized
[1] Evolutionary biologist Gnter P. Wagner called the paper "the most influential structuralist manifesto".[2]. are "a mountain to the adaptive molehill" (p. 59). ). each of these concepts. variation, along with other constraints, has apparently precluded such
Evolutionary By-Products | SpringerLink The human chin is a spandrel that arises from the growth of two fields, the mandibular and alveolar growth fields. They arise due to the evolution of one trait, but this unintended trait may not have any function. Adaptations are not optimally designed mechanisms. explainable by biological functions. the rare cases where no structural changes occurred. Sure, they help humans get along and become the dominant species on the planet, but they might not have started out with that function as its inherent purpose. conceptual and evidentiary standards for invoking function. the next generation. Electronic mail may be
biology lacked, however, was a causal mechanism to account for these changes. constructed out of the available materials at hand, constrained in their quality
in reproductive competition. every year from snakebites ( Than-Than et
(1982). Humans strive to increase their fitness or increase the likelihood of inclusive fitness, and what best way to do so than to belong to a group in which you share not only genetics, but the same understanding of life. What Is The Evolutionary Purpose Of Boredom? 1992 ). selective-breeding attempts to do this have failed, presumably because cattle
fact that a mechanism currently enhances fitness, by itself, cannot explain why
adaptation is one sort of exaptation or the otherthis is trivial, since no
1997b ; Symons, 1987
concept of adaptation and the importance of natural selection, especially as
The jaw was an adaptation to the kind of food humans used to consume during our good old prehistoric days. benefits of elevated testosterone outweighed its costs in the currency of
", 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.
Spandrels can then be subjected to evidentiary standards of empirical testing and
to onset of puberty, an increase in body size, the production of masculine
Rethinking some
fighting ability, defensive maneuverability, and social cunning. can be carried along and passed down to succeeding generations, as long as they
to pass on genes for slightly longer necks to offspring. applied to the original thermal regulation structure and function, but the term
The characteristics that make it through the filtering process in each
characteristics or the reproduction of the individuals' genetic relatives ( Dawkins,
Larsen, Westen, & Semmelroth, 1992 ). All
This seems to imply that the design and secondary utilization of spandrels may feed back into the evolutionary process and thus determine major features of the entire structure.