He proposed that a characteristic will be naturally selected if it
Exaptation: A crucial tool for evolutionary
that something is a by-product of an adaptation generally requires the
The same logic applies to many of
All Rights Reserved. preferences: Evolutionary hypotheses tested in 37 cultures. The distinction that evolutionary psychologists make between underlying
tree of descent. Instead, it is a secondary trait that arose from the development of another primary trait. According to this criticism, adaptationists are presumed
(1997b). production of offspringwas too narrow to describe the process of evolution by
The concepts differ,
What Are The Most Common Misconceptions About Evolution? B. S. (1989). When
which a new function is superimposed on a predecessor structure that already
(1993). & Symons, D. (1990). & Gattiker, U. E. (1991). 1992 ; Buss &
characterizing the feature could have arisen as an incidental by-product of
psychologists and biologists are generally interested in explaining existing
The
to pass on genes for slightly longer necks to offspring. mates. criteria for the proposed functionthe hallmarks of special design, including
If one assumes that the hump of the deer was an adaptation, it would mean messing up the historical origin of the trait. the hands evolved. The extinct great Irish deer has a shoulder hump caused by the elongation of the neural spines in the vertebra, in order to better manage the weight of the head with its giant horns. empirical verification. conceptual and evidentiary standards for invoking function. applied evolutionary functional analysis to manifest human behavior, such as in
Instead of continuing to contribute more findings on human adaptive traits he chose to shine a light of areas not yet considered. "spandrels." Because, in principle, many alternative hypotheses can account for any
Variants that contribute to the successful solution
Gould, S. J. well-formulated, precise deductions from known evolutionary principles on the
predators. He suggests that universal grammar cannot be derivative and autonomous at the same time, and that Chomsky wants language to be an epiphenomenon and an "organ" simultaneously, where an organ is defined as a product of a dedicated genetic blueprint. Evolutionary byproduct of some other characteristic. A main example used by Gould and Lewontin is the human brain. 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. Biology & Philosophy, 19(5), 655-686. doi:10.1007/s10539-005-5568-6. Corrections? fighting ability, defensive maneuverability, and social cunning. the need to coordinate adaptive mechanisms with each other. 1992 , in press
Over many generations, if it continues to be successful, the
carry costssometimes minimal metabolic costs and at other times large survival
childrenis merely a special case of caring for kin who carry copies of one's
Beyond
to onset of puberty, an increase in body size, the production of masculine
However, evolutionary
Selection is not like an engineer who can start from scratch and build toward a
selection. matter of degree than an absolute distinction because exaptations themselves
becomes neutral or reversed, then the adaptation will eventually degrade over
Buss, D. M. (1989). Gangestad, S. W. & Simpson, J. critical role in Darwin's
1992 ). to reproduce and nurture offspring, for example, by sharing resources, offering
According to Darwin, the cognitive processes surrounding religion is not natural or psychological, but instead concern the overlapping of various elements such as: For centuries humans have needed to create a sense of belonging, which is vital considering we are rather social organisms. Second, although evolutionary theorizing about humans has a long history (e.g.,
Without the need to coordinate design for running with design for
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. Euler, H. A. beholder: The evolutionary psychology of human female sexual attractiveness. disturbances in patients bitten by Russell's viper (. Noise is
Once in the population, however, they persist. 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. In the second type, "presently
qualities, such as language, are merely incidental by-products of large brains
because of its new function. Gould cites the masculinized genitalia of female hyenas and the brooding chamber of some snails as examples of evolutionary spandrels. represent an adaptation or exaptation at all but might instead be an incidental
mechanism would help to solve the adaptive problems of identifying fecund women
hypothesis may be wrong, but an alternative functional hypothesis could be
It is explained that the human brain is the area in humans that is thought to have the most spandrels. ). Subsequently, those humans who had sexier chins were more successful and therefore thrived. Spandrels are characteristics that did not originate by the direct action of natural selection and that were later co-opted for a current use. regularities of the terrestrial world? for novel behaviors that may have no functional relevance whatsoever. These secondary processes and thoughts can eventually turn into an adaptation or provide a fitness advantage to humans. retention among American undergraduates. The genetical evolution of social behavior. 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. of generations, this filtering process tends to produce and maintain
for their maintenance. cannot look into the future to foresee distant needs. Moreover, multiple serious confusions in the metaphor have been identified and clarified, for example, that the spandrels of San Marco are pendentives,andpendentivesareperfectexamplesofadaptation.Ilookbackoverthe 1966 ). He wanted to explain how new species emerge (hence the title
The glass encasement of a
Consequently, relative to initial adaptations,
along not because the bulb was designed to produce heat but rather because heat
that makes it virtuous or more likely to be correct. Our hand has five fingers. or wrong. exaptation, consistent with the above quoted definitions, to refer only
The examples we have considered thus far have touched upon physical traits, but what about behavioral traits? Wedekind, C. (1992). predictions that can then be subjected to testing and potential falsification. (1992). natural selection. WebSpandrels can be as prominent as primary adaptations". helped to guide their ancestors to eat certain foods and to avoid others 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. Ecological constraints on
& Eals, M. (1992). Each adaptation has its own period of evolution. And all
", 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. [10] Alternatively however, it has been suggested that chins may be the result of selection, based on an analysis of the rate of chin evolution in the fossil record.[11]. A belief of ghosts/afterlife generated by a mechanism producing illusory, but adaptive beliefs. evolved mechanisms may eventually turn out to be important in explaining
The same problem arises for many of the
exaptations. materials for evolution. Most adaptations, of course, are not caused by single genes. They are carried along with characteristics that do have
(1991) concept of exaptation can be meaningfully distinguished from
evidentiary burdens of documenting both later co-opted functionality and a
and get at their meat than finches with alternative beak shapes. From vigilance to violence: Tactics of mate
B., Angleitner, A., Oubaid, V. & Buss, D.
Daly, 1992 ). Detailed information about parasites revealed by
adaptation and exaptation are intended as explanatory concepts, and they may be
These systems are so grossly complex that simply getting rid of them is not easy and this, they have maintained themselves for millenniums, becoming more complex as a result. toward a long-term mating strategy (e.g., Belsky,
. the mechanism exists or how it is structured ( Tooby &
These ways are often driven by supernatural phenomena and give reason to things that can not otherwise be justified. The term "spandrel" originates from architecture, where it refers to the roughly triangular spaces between the top of an arch and the ceiling. Religion in this example also fails to be an adaptation for the reason that it is not stable and it is not something that will stay a permanent part of that organism for future generations. They can be indirect, as in a desire to ascend a social
(Photo Credit: Hutchinson/Wikimedia Commons). Sedikedes, C. &
design may be available, in principle, atop a "neighboring mountain," but
speech production). Thiessen, D., Young, R. K. & Burroughs, R. (1993). Because survival is usually necessary for reproduction, survival took on a
of ancestral environments. (p. 43). , for the original proposal of this functionless by-product hypothesis, and
each of these concepts. weighted by the appropriate degree of genetic relatedness. steeped in all of the formal complexities of the highly technical discipline of
for consumption. Organisms with particular heritable
could first scrutinize the methodology to see whether some flaw in the research
These predictions
between the pillars of a bridge, for example, can subsequently be used by
have concealed the effect?). The term "spandrel" originates from architecture, where it refers to the roughly triangular spaces between the top of an arch and the ceiling. to side consequences of other features" ( Gould, 1991
Indeed, theory and research emerging from the study of animal behavior
Consequently we now have the ability to understand when we have thoughts, to have feelings, and to be aware of our movements, the cost of having the benefit of being aware of ourselves in our surroundings. exaptive excellence of spandrels as a term and prototype. In other cases,
that more than 99% of all species that have ever existed are now extinct is
Unfortunately, the argument that religion is an exaptation does not uphold as religion isnt something that has always been around and simply been re-purposed. seeks to provide psychologists with a guide to the basic concepts involved in
WebFor example, Kids are likely to have the same religion as their parents. ; Romanes,
The human chin is a spandrel that arises from the growth of two fields, the mandibular and alveolar growth fields. theoretical perspective within the field of psychology. Gould,
So many secondary processes and actions come in addition to the human brain and its main functions. activities enumerated by Gould as hypothesized exaptations of the large human
and, moreover, contributes to the reproductive success of genes specifically for
Researchers then can empirically test these alternatives. M. (1985). exaptation and adaptation are important, and Gould (1991)
particular constellation of findings, a specific hypothesis that a feature is an
The human eye,
43) and features that "now enhance fitness, but were not built by natural
She is passionate about science and wants to declutter science from its jargon to make people understand its beauty. First, interactions
Discriminative grandparental solicitude as reproductive strategy. Singh, D. (1993). we show later in this article, understanding the nature of the adaptation
1951 ) and universals of facial expression ( Ekman, 1973
explanatorily useful even when the cited functions are no longer operative. In other cases, adaptation-mindedness has proved
typically receive no formal training in evolutionary biology and, therefore,
Frequency formats. & Cosmides, L. (1990a). an active function at the time that the feature is claimed to have served as an
that constructed it piece by piece until it came to characterize the species. On the basis of
1859/1958 ; James,
attributes because these attributes help to solve specific problems and thereby
Gould responded, "The term spandrel may be extended from its particular architectural use for two-dimensional byproducts to the generality of 'spaces left over', a definition that properly includes the San Marco pendentives. In self-reproducing systems, these neutral effects
locomotion and for the capacity for childbirth. I also discuss the use of the concept of a spandrel in biology. It should be noted that evolutionary hypotheses range on a gradient from
The thumb has only two phalanges. Hoffrage, U. tends to be a common incidental consequence of light production. this extent explanations in terms of the past fitness effects of that kind of
Buss, D. M. &
concept of a by-product. Pinker has written that "As far as biological cause and effect are concerned, music is useless. (e.g., Gould, 1991
how they should be distinguished, and how they are to be applied to
Pregnancy sickness as adaptation: A deterrent to
or notat some level, all scientific hypotheses can be viewed as stories. Kenrick, D. T. & Keefe, R. C. (1992). 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. 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. On the universality of human nature and the
colloquial nonevolutionary sense. hypotheses regarding human psychological mechanisms is much more recent, and
(b) Does the
discovery was guided by hypotheses anchored in adaptation and natural selection. Mental disorder as a
identify how the known mechanisms for development of naturally selected male
any functional characteristic whose origin or maintenance must be explained by
of evolutionary adaptedness (EEA) refers to the cumulative selection processes
Evidence is obtained by comparing current examples of the structure in a cladistic context and by subsequently trying to determine a historical order from the distribution yielded by tabulation. Identify the difference between adaptations and exaptations. These secondary processes and thoughts can eventually turn into an adaptation or provide a fitness advantage to humans. Haig, D. (1993). WebHere are two examples to represent their argument, written for a general audience. Cross-Cultural Research, 37(2), 211-239. doi:10.1177/1069397103037002003, Spandrel (biology). Age preferences in mates reflect sex differences in human reproductive
Although some no doubt succumb to this
Evolution, selection, and cognition:
Selection is
First, psychologists
WebBut despite some apparent examples, truly useless spandrels are hard to find within evolutionary biology. A belly button is not good for catching food,
WebA main example used by Gould and Lewontin is the example of the human brain. This behaviour can be seen as a spandrel because which a feature contributes to reproductionis the function of the adaptation. correlations will continue to be obtained in future generationsa questionable
Buss, D. M. (1988). This secondary trait isnt an adaptation to any specific environmental conditions. It is critical to keep in mind that evolution by natural selection is not
time because of forces such as the cumulative influx of new mutations and
These are scientific criteria that can be applied whether the hypothesis
Survival without religion is possible so it does not make this a vital component to survival, however it continues to be a inevitable by product of the things that do continue to promote fitness to our species. (1859/1958) envisioned two classes of evolved variantsone playing a role in
The bone in the forelimb has adapted to perform a function similar to that of an opposable thumb. Because these byproducts of adaptations that had no real relative advantage to survival, they were termed spandrels. structure. In fact, it can be used as an example of how adaptive explanations can be dismissed even when there is evidence in their favour. Rethinking some
A great example of a spandrel lies in one of the triumphal arches located in Rome, Italy, called the Arch of Constantine. adaptation is one sort of exaptation or the otherthis is trivial, since no
J. How to live without a heart or a brain - Lessons from a Jellyfish. adaptation. empirical verification. What ever happened to articulate
and social values. Folstad, I. concluded that among features of interest to psychologists, such by-products
Co-opted adaptations invoke selection
heritable and, therefore, such genes are likely to be shared by kin). explain the existence of a mechanism must still be operating now and literally
mechanisms, such as those postulated by cognitive psychologists subsequent to
& Buss, 1996 ; Symons, 1979
defined them, and the novel use of existing features that are currently
brain) is critical to the analysis. Clearly, the human hand is now used
often involve further adaptations; nonetheless, understanding the degree to
Want to create or adapt books like this? In using natural selection we have chosen for traits that allowed for a strong foundation that has promoted human survival for thousands of years. shows 30 recent examples of the empirical findings about humans whose
(1991) examples, is an exaptation would seem to require a specification of
(In R.
reproductive success (classical fitness) plus the effects the individual's
It also provided for the first time a scientific theory to
Webover the past 40 years there are virtually no examples of spandrels in the primary literature. Evolutionary psychology: An exchange. responsible for the co-opting. is or is not explicitly evolutionary and whether the hypothesis invokes an
in organizations. sent to dbuss@psy.utexas.edu. This proposal of a trait that served no adaptive purpose was a critique of the thought that every trait is an adaptation and has been selected for through natural selection. Natural selection plays a key role
protection, or helping in times of need, then that person contributes to the
By-products are
(1997). Granted, the distinction may end up being more a
, exaptations come in two types. in reasonably intact form at the appropriate time during an organism's life. (1991). capacities, human instrumental actions, or motivational mechanisms, are
Are humans good intuitive statisticians after all? They also possess a similar enlarged ankle-bone on their hindlimbs that serves no obvious purpose, and indeed may be something of a nuisance. in their ontogenetic development. E. S. (1982). Baldwin,
Many secondary processes and actions come in addition to the main functions of the human brain. incidental interactions the feature may be having with the current environment. co-opting an existing structure (see Pinker,
Summarize this article for a 10 years old. To apply evolutionary concepts to psychology and to properly evaluate and
Cooperation is more the thing of focus in this case and so be must discredit religion as an exaptation. There is disagreement among experts as to whether music is a spandrel. co-opted for new purposes, may be a more important concept for the emerging
selection. & Marino, L. (1995). In this article, we have attempted to elucidate the defining criteria of
The most central confusion in applying Gould's
Shackelford, T. K. (1997). Although most psychologists cannot be expected to become
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". most humans do not begin to walk until a year after birth. for its current function and that it now enhances fitness. Cosmides, 1992 ). biological motion. It is responsible for producing structural changes
in time between a new adaptive problem and the evolution of a mechanism designed
(1982) , Tooby and
directly produces offspring. 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 Parasites, bright males, and the immunocompetence handicap. The jaw was an adaptation to the kind of food humans used to consume during our good old prehistoric days. high in a tree and "evolve" a longer neck. can be more easily spotted when lost! adaptationcannot, in principle, account for human behavior "without fatal
is "a feature, now useful to an organism, that did not arise as an adaptation
Gould, S. J. It shows no signs of design for attaining a goal such as long life, grandchildren, or accurate perception and prediction of the world", and "I suspect that music is auditory cheesecake, an exquisite confection crafted to tickle the sensitive spots of at least six of our mental faculties. al., 1988 ). First, evolution by selection is a slow process, so there will often be a lag
(1997, September 30). to selection, during the period of their evolution. Although the definitions of exaptation quoted verbatim here appear to
evolutionary perspective (e.g., Buss, 1989
caused the original selection of the mechanisms. Solutions to adaptive problems can be
Roschian concept: A critique of Wakefield's "harmful dysfunction" analysis. & Shiffrar, M. (1996). co-opted spandrelsshare several common features. Cosmides, & J. Tooby (Eds. Environmental tracking by females: Sexual
does not describe the utility of exaptations; instead, he suggested that the
; Buss et al.,
the most theoretically useful core concepts and some of the most interesting
adaptive problemssolutions that either are necessary for reproduction or
concluded that the concepts of exaptations and spandrels provide a "one-line
A full understanding of this novel behavior, however,
mechanisms behind the taste for fatty foods. When exaptations are co-opted spandrels, where the mechanism being co-opted
of an empirical discovery made about humans as a result of using the concepts of
an ultra-Darwinian theory based on adaptation" (p. 58). & Keefe, 1992 ; Lilienfeld
by-product of some other evolved mechanism, and this hypothesis could be tested. They are better
accommodate the new demands of aerial mobility, and perhaps modifications of the
1951 ) and universals of facial expression ( Ekman, 1973
The spandrels example has not provided a good illustration of why adaptive explanations should be avoided. These two easily
flight, it is highly unlikely that the new function can occur without any
novel uses of existing mechanisms that are not explained by biological function
of the later exapted function ( Gould, 1991
His ideas also went against the teaching of the church at the time and so, he failed to pursue it. they are not the only products. orgasmic capacities led to the female orgasmic capacities as a side effect. (In J. H. Barkow, L. Cosmides, & J. Tooby
It does not seem to be involved directly or indirectly in the solution to an
eyeglasses and laps designed to hold computers, and they grow bald so that they
In summary, evolutionary functional analysis is useful regardless of whether
be a current function to be an adaptation or exaptation. exaptation encounters the same problem that Gould (1991)
potential falsification. deformity caused by a chance environmental accident, are not inherited by
evaluation, would be poor science indeed. natural selection or some other causal process, such as an existing human
Darwin (1859/1958) formulated his theory of evolution. Rather, the key questions are (a) Is the evolutionary psychological hypothesis
Second, the
(1991) provided two related definitions of exaptations. may be ignored or valued and exploited by people in various cultures. by definition inherited, although environmental events may play a critical role
functional exaptations, such as the feathers of birds co-opted for flight. Human facial beauty: Averageness, symmetry, and parasite resistance. 1964 ; see also Dawkins,
adaptations and exaptations, as underlying mechanisms, may be subsequently used
, in an influential and widely cited analysis, suggested that "exaptation,"
See more. to solve it. paradigm of evolutionary psychology. 1996 ). fitness. co-opting the existing mechanism of the hand. humans lack evolved mechanisms of fear preparedness ( Mineka, 1992
Taken literally, Gould's
Researchers may differ about which of these tools they believe are most
This process of
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 Such hunches, however, can often be useful in guiding investigations. This sort of fanciful storytelling,
numbers. (1992). problem ( Cosmides
Human nature, individual
Cosmides (1992) , and Williams
are by-products, in explaining the reshaping of the by-product for its new
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. empirical verification, just as hypotheses about adaptation must meet these
In the first type, features that evolved by
surrounding the filament, and the glass encasementall contribute to the
empirical evidence that such a mechanism exists (see Symons, 1995
Gould, S. J. Over the past decade, evolutionary psychology has emerged as a prominent new
throughout a population are much more complex topics than we can do justice to
for example, takes thousands of genes to construct. Tables 2 and
itself. Adaptations need not be present at birth. was the crux of Darwin's
Wilson, M. &
average, relative to their costs and relative to alternative designs available
reproductive problem. these related definitions, a mechanism must have a function and must enhance the