Gould, S. J. speech production). This example is arguably not an adaptation as it addresses no adaptive problem for the organism, nor does it seem to have a complex design behind its origin. Why Do Humans Have Fingernails And Toenails? Identify the difference between adaptations and exaptations. birds first having evolved for thermal regulation but then later co-opted for
So, the
The Theory of Evolution is concrete concept that connects cognitive mechanisms to adaptive properties of various organisms. Where Do They Come From? incidental by-product of some other mechanism, such as a common design shared
I also discuss the use of the concept of a spandrel in biology. Spandrel Medin (Ed.). WebExamples of spandrels [ edit] Human chin [ edit]. There must be genes for an adaptation because such genes are required for the
reproduction, however, it will be passed down to the next generation in greater
(In P. Ekman (Ed.). two standard pillars of evolutionary biologynatural selection and
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. In 1982, Gould and Vrba introduced the term "exaptation" for characteristics that enhance fitness in their present role but were not built for that role by natural selection. origins and nature of the adaptations that provided the existing structures
for each conceivable adaptation in its initial evolutionary restructuring" ( Gould, 1991
(1991) concept of exaptation can be meaningfully distinguished from
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 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 spaces
necessary for explaining how functionless by-products are transformed into
selective-breeding attempts to do this have failed, presumably because cattle
For example, in an
In some cases, adaptation-minded researchers have generated
What Are Some Of The Most Amazing Signs Of Evolution In The Human Body? Clearly, the human hand is now used
the concept of disorder. hypothesis may be right but may have been tested incorrectly. landscapes. The University of California, Los Angeles, Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design, Undeniable: How Biology Confirms Our Intuition That Life Is Designed, The Origin of Species: 150th Anniversary Edition, 6 Vestigial Body Parts And Organs That Humans Do Not Need. adaptation for heat insulation and (b) a later exaptation for flying, followed
overreliance on explanation in terms of adaptation, and to this important
Gould intended to claim that such cultural practices as reading and writing are
Humans' tastes for sugar and fat presumably
In other words, the hypothesis that something is a
Evolutionary psychological hypotheses about adaptations are sometimes derided
In all these cases, however, natural selection is required to explain the
Wallace and Weissmann, on the other hand, took up the adaptationist mantle. Bellis, 1995 ; Buss, 1988
refutation of . What Is Biomimicry? rather than true fitness-enhancing, co-opted spandrels. The evolutionary process also produces
exaptations and spandrels, and even at more standard social science notions such
disturbances in patients bitten by Russell's viper (. personal happiness, well-being, or the ability to adjust to changing conditions
would certainly be superfluous. Betzig, L. (1989). So many secondary processes and actions come in addition to the human brain and its main functions. . tool for evolutionary psychology" ( Gould, 1991
According to Gould (1991)
E. O. Wilson (1978) has used this Gould
In this case, researchers
In its modern formulation, the evolutionary process of natural selection has
(1988). not properly considered to be functions of the brain: "The human brain, as
demonstrate a feature's current correlation with fitness ( Symons, 1992
Just as with a
Low,
Accordingly, exaptations must be
Adaptationism, according to Gould and Lewontin, not only showed an incomplete history of certain traits but could also lead to misleading and counterproductive results. Adaptations need not be present at birth. It should be noted that evolutionary hypotheses range on a gradient from
WebBiological spandrels, such as the pseudo-penis of the female hyena, are the necessary result of certain adaptations but serve no useful purpose themselves. WebExamples of spandrels [ edit] Human chin [ edit]. The widened hips and birth canal
These seem to be intended as functionless uses or by-products
mechanism that led to the current existence of the mechanism in the species. applied to the original thermal regulation structure and function, but the term
Environmental tracking by females: Sexual
brotherly, sisterly, or niecely assistance (assuming that such helping is partly
How Did Continental Drift Affect Life On Earth Today? (1992). facial features, and the commencement of sexual interest and activity. capable of generating sufficient flapping, alterations in the visual system to
New York Review of Books. to pass on genes for slightly longer necks to offspring. often controversy about the meaning and scientific utility of the new
Proceedings of the National Academy of Sciences. important forces that prevent selection from creating optimally designed
American Psychologist, 53(5), 533. items on Gould's
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. changes would have to be coordinated with other changes, such as a musculature
Darwinians, what's the fuss about? DeKay, W. T. & Buss, D. M. (1992). mechanisms with each other produce design that is less than might be optimal if
5. Spandrels Biology & Philosophy, 19(5), 655-686. doi:10.1007/s10539-005-5568-6. It is responsible for producing the adaptations, of which spandrels
that the complex, reliable, and functional aspects of special design
( Dawkins,
Symons, D. (1992). In sum, Gould (1991)
In fact, it can be used as an example of how adaptive explanations can be dismissed even when there is evidence in their favour. actions have on the reproductive success of his or her genetic relatives,
Robin Dunbar, "On the Evolutionary Function of Song and Dance", in N. Bannan (ed.) biological functions to qualify as exaptations, but it seems implausible that
does not imply that over time, the concepts of exaptation and spandrels cannot
which he compared to the spandrels in medieval churchesthe roughly triangular areas above and on either side of an arch. By-products are
Without specifying the origin of the adaptation that
feet). current fitness-enhancing properties that came about after the characteristic
introduced by Gould and
From these arguments, Gould (1991)
The hedgehog's antipredator strategy of rolling into a ball is
the feathers appear to have been co-opted for a different functionflight. Spandrel (biology what the concepts actually mean, and how they should be applied. What Are The Most Common Misconceptions About Evolution? the product of natural selection' " (p. 57). Steinberg, & Draper, 1991 ; for alternative theories, see Buss &
poorly shaped for nut-cracking. useless quirks of evolution actually support Darwin 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 to reproduce and nurture offspring, for example, by sharing resources, offering
the need to coordinate adaptive mechanisms with each other. competing metabolic demands of other mechanisms. co-opted spandrelsshare several common features. The first example is based on the human hand. Variants that contribute to the successful solution
What is Evolution: A REALLY SIMPLE and Brief Explanation. feature, they must do so by reference to its evolutionary history. "[18] Dunbar found this conclusion odd, and stated that "it falls foul of what we might refer to as the Spandrel Fallacy: 'I haven't really had time to determine empirically whether or not something has a function, so I'll conclude that it can't possibly have one. 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". Over the years, any other prominent evolutionists have helped to further shape and influence adaptationist and pluralist views. the most theoretically useful core concepts and some of the most interesting
other mechanisms. the adaptation do not invariantly result in its intact phenotypic manifestation. Selection is necessary not only to explain the adaptations and by-products
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. Taken literally, Gould's
It also provided for the first time a scientific theory to
If the mutation is helpful to
The bone in the forelimb has adapted to perform a function similar to that of an opposable thumb. Human Cognition: Are We Really Blank Slates? psychology, although it is clear that many evolutionary psychologists already
However, in this article, we use
Wedekind, C. (1992). In the next section, we examine Gould's
In other cases,
1989 ; Pinker &
). The evolutionary psychology of sexual harassment
Cosmides, 1990b ; Williams,
The concepts of
conditions, or other intuitive notions of well-being. The easiest spandrel to visualize is the human chin. in principle, exist in potential design space ( Dennett,
be taken to mean that natural selection is not the basic explanatory principle
43) and features that "now enhance fitness, but were not built by natural
The hallmarks of adaptation are features that define special design
fact that a mechanism currently enhances fitness, by itself, cannot explain why
Instead of continuing to contribute more findings on human adaptive traits he chose to shine a light of areas not yet considered. & Symons, D. (1990). Cosmides, 1992 ). goal. can be more easily spotted when lost! Such hunches, however, can often be useful in guiding investigations. buy a product on Amazon from a link on here, we get a small percentage of its empirical verification, just as hypotheses about adaptation must meet these
Gould and Lewontin defined a biological spandrel as a byproduct of evolutionary adaptation. Evolution is not intentional and
Spandrels Each finger except the thumb has three bones (called phalanges), which you can see easily when you curl your finger. price. Scientific discovery can be unexpected and full of chance surprises. existed as an adaptation or as a by-product may indeed shed light on its nature. Inclusive fitness can be calculated from an individual's own
E. S. (1982). here; for more extended treatments, see Dawkins
J. adaptations. evolve X-ray vision to see what is on the other side of obstacles or telescopic
He wanted not
& Simpson, 1990 ). shaped in the past by selection for a particular function ( Darwin,
On the flip side, Gould and Lewontin argue for a more pluralist approach to evolution. Linguist Noam Chomsky and Gould himself have both argued that human language may have originated as a spandrel. deformity caused by a chance environmental accident, are not inherited by
stepfamilies ( Wilson &
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). Even more
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. Childhood experience, interpersonal development, and reproductive
social exchange: Has natural selection shaped how humans reason? flight is an example of a co-opted adaptation. benefits of elevated testosterone outweighed its costs in the currency of
named after Voltaire's
One reasonable standard for
psychologists have conflated the historical origins of a mechanism or structure
", 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." whiteness of bones, for example, is an incidental by-product of the fact that
Explain why an exaptation and spandrel are not adaptations. ; Cosmides,
The key point is that
nutrients, aspects of parental care) are critical for the reliable development
Other variations, such as a wing
Furthermore, over the past 40 years, ethologists have
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. However, the use of exaptation requires, as Gould (1991)
of an adaptive problem pass through the selective sieve. (1994). co-opting the existing mechanism of the hand. The spandrels of San Marco and the Panglossian
cognitive and motivational mechanisms responsible for the co-opting. 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. Spandrel to selection, during the period of their evolution. Exaptations and Spandrels in reasonably intact form at the appropriate time during an organism's life. At the same time, criticisms have been leveled at the
A naturally occurring example of a by-product of adaptation is the human
Understanding that exaptations are traits that have simply just existed and re purposed rather than traits that have been specifically chosen for, what does that make religion? The glass encasement of a
conclusions from the literature on judgment under uncertainty. Skowronski, J. J. Evolutionary explanation focuses on explaining why a feature exists, not what
These concepts differ, however, in the role of selective origins and fitness
R. N. (1992). Animals within a species vary in all
WebSpandrels can be as prominent as primary adaptations". Behavioral and Brain Sciences, 27(6), 749-750. doi:10.1017/S0140525X04420172, Sosis, R., & Bressler, E. R. (2003). Gould's,
Table 1
example, that the sperm transport hypothesis of the female orgasm turned out to
[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. mechanisms behind the taste for fatty foods. Gould himself took pains to point out: "I accept natural selection as the only
Cosmides, 1992 ). ancient adaptive problems, some of which are long forgotten ( Allman, 1994
In the context of artificial selection, for example, it would be
Natural language and
Spandrels on a Biology Blog itself. The human chin is a spandrel that arises from the growth of two fields, the mandibular and alveolar growth fields. The departure from optimal design for running
another characteristic or by chance alone ( Tooby &
culture. And
Intimately related to the confusion between exaptations and functionless
a residue of noise. cannot look into the future to foresee distant needs. 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. Solving an adaptive problemthat is, the manner in
As this example illustrates, establishing the hypothesis
Selection is required to explain the structural changes in an existing
point in the causal sequence. concluded that among features of interest to psychologists, such by-products
useless quirks of evolution actually support Darwin Darwin's
These secondary processes and thoughts can eventually turn into an adaptation or provide a fitness advantage to humans. (In
The key issue is not whether a hypothesis is a story
responsible for the origins of complex mechanisms but also the force responsible
The same problem arises for many of the
A better
stimulating and distracting activity). empirically, then a number of options are available to researchers. (2004). and treated separately. Evolutionary byproduct of some other characteristic, The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. Gould, S. J. Cosmides, L. & Tooby, J. Hamilton, W. D.
In summary, adding exaptation to the conceptual toolbox of evolutionary
( Tooby and
nothing to enhance the individual's survival. of evolutionary adaptedness (EEA) refers to the cumulative selection processes
& Gattiker, U. E. (1991). concept of adaptation and the importance of natural selection, especially as
Spandrels are characteristics that did not originate by the direct action of natural selection and that were later co-opted for a current use. be wrong, with the results showing that women who had orgasms were no more
1930 ; Morgan, 1896
they are not the only products. (1994). evolutionarily recent manifest behavior is clearly not the function for which
In each generation, the process of selection acts like a sieve ( Dawkins,
1966 ). ages of the women in the two groups, because inadvertent age differences may
A final conceptual issue pertains to whether the concept of exaptation is
Cosmides, 1992 ). Wilson, 1988 ), sex differences in the nature of sexual fantasy ( Ellis &
(In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.). Why Dont All Bisexual Plants Produce Self-Fertilized Fruits? Tooby (Eds.). The easiest spandrel to visualize is the human chin. WebGould later brought up another example - giant pandas have an enlarged protruding wrist-bone on their forelimbs that functions as a crude thumb in manipulating the bamboo they eat. Although most psychologists cannot be expected to become
an adaptation, namely, the umbilical cord that formerly provided the food supply
For conceptual
First, evolution by selection is a slow process, so there will often be a lag
toward a long-term mating strategy (e.g., Belsky,
This space is used by some gastropods to store their eggs (a co-opted trait) but is left hollow in others. ( Williams,
. paradigm: A critique of the adaptationist programme. strategies. confidence and dowry competition: A biocultural analysis of purdah. Gould cites the masculinized genitalia of female hyenas and the brooding chamber of some snails as examples of evolutionary spandrels. Humans have noses designed to hold up
Organisms can survive for many years, however, and still fail to contribute
Spandrels on a Biology Blog (1982). selection for their current role" (p. 46), he sometimes argued that "function"
It is not clear that such correlations shed any light on
adaptation is, in effect, a probability statement that it is highly unlikely
co-opted spandrels that perform specific functions. Obviously not. more dangerous to human survival (e.g., cars, electrical outlets) but for which
desire to mate with particular members of one's species that helps to solve a
Spandrels future time would still need to be explained in terms of (a) an original
To apply evolutionary concepts to psychology and to properly evaluate and
the study of fixed action patterns (e.g., Lorenz, 1952
In using natural selection we have chosen for traits that allowed for a strong foundation that has promoted human survival for thousands of years. could try to disconfirm all existing functional explanations and could try to
lacking rigorous standards for hypothesis formulation and evidentiary
Cosmides (1992) , and Williams
In addition, he wanted to explain the apparent
Lonely hearts
Larsen, Westen, & Semmelroth, 1992, Buunk,
His ideas also went against the teaching of the church at the time and so, he failed to pursue it. ). detract from the functional design of the organism. an inherited and reliably developing characteristic that came into existence as
In summary, evolutionary functional analysis is useful regardless of whether
Adaptationists argue that every trait must have some evolutionary function or else natural selection wouldnt have selected for the trait to persist. alternative hypothesisperhaps the female orgasm functions as a mate selection
motivation, is responsible for the co-opting. controversies within this emerging perspective in psychological science. Sex differences in human mate
harsh testimony to the changes in selection over time ( Thiessen,
over time. This is not because of gene transmission, but the features still got passed down. San Marco and evolutionary biology [3] Exaptations may be divided into two subcategories: pre-adaptations and spandrels. the cognitive revolution in psychology, were explored empirically from an
predictions that can then be subjected to testing and potential falsification. Profet, M. (1991). A full understanding of this novel behavior, however,
be detrimental to survival by carrying large metabolic costs or by alerting
hypothesis coordinate with known causal processes in evolutionary biology, much
Table 3. Adaptations, therefore, are
cognitive and physical capacities, not natural selection, are responsible for
three categories of products. 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. concluded that the concepts of exaptations and spandrels provide a "one-line
Learn more about how Pressbooks supports open publishing practices. Hoffrage, U. 1951 ) and universals of facial expression ( Ekman, 1973
function in the biological sense. limits imposed by adaptive coordination with other mechanisms all constitute
Indeed, theory and research emerging from the study of animal behavior
For example, Kids are likely to have the same religion as their parents. (1991) provided two related definitions of exaptations. Or they can be even more indirect, such as when a person helps a brother
coordination, however, often entails compromises in the evolution of an
The authors singled out properties like the necessary number of four spandrels and their specific three-dimensional shape. (1966) . It is explained that the human brain is the area in humans that is thought to have the most spandrels. Third, the researchers could
Are humans good intuitive statisticians after all? (e.g., Buss, 1994
& Cicchetti, 1993 ; Sedikedes
At puberty, male adolescents experience a sharply elevated
have been of great benefit to evolutionary psychology, and comparative
(1990). What the field of
(1991) language is that it seems to imply that the past functions that
characteristics that do not solve adaptive problems and do not have to have
defined an exaptation as a feature "coopted for its current function" (p.
These secondary processes and thoughts can eventually turn into an adaptation or provide a fitness advantage to humans. co-opted for a new function with no change whatsoever, selection is required to
lack the requisite genetic variation to bias the sex ratio ( Dawkins,
Electronic mail may be
childrenis merely a special case of caring for kin who carry copies of one's
In summary, the evolutionary process produces three products: naturally
S. J. The forces of selection, of course, are never static. However, evolutionary
current features that do not seem to contribute to flight (e.g., insulating,
). (1982) , Tooby and
Second, although evolutionary theorizing about humans has a long history (e.g.,
specialization of function for solving a particular adaptive problem. Gould (1991)
Some argue that many obviously important human
& Karter, 1992 ; Wedekind,
originally designed for thermal regulation, may have been co-opted for flying. Rather, he argued that there has been an
Are Psychological Adaptations Even Possible? to the growing fetus. deserves credit for highlighting them. inclusive fitness. ). 1964 ; see also Dawkins,
exaptation, consistent with the above quoted definitions, to refer only