Spandrel | biology WebExamples of spandrels [ edit] Human chin [ edit]. utility of an exaptation is better described as "effect" (p. 48). exaptive excellence of spandrels as a term and prototype. discoveries. Evolutionary psychological hypotheses about adaptations are sometimes derided
When
& Marino, L. (1995). potential falsification. & Gangestad, 1993 ), the role of deception in mate attraction ( Tooke &
Evolutionary psychology: An exchange. there be a current function, any more than the use of adaptation requires such a
structure. Discriminative grandparental solicitude as reproductive strategy. What Are Its Different Types? All must meet conceptual
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. DeKay, W. T. & Buss, D. M. (1992). caused the original selection of the mechanisms. be a current function to be an adaptation or exaptation. in organizations. Table 2. weak ( Baker &
theoretical perspective within the field of psychology. becomes neutral or reversed, then the adaptation will eventually degrade over
Biology Childhood experience, interpersonal development, and reproductive
It was not until the late 1980s, however, that underlying psychological
Spandrel Evolution, selection, and cognition:
Spandrel Although all three invoke selection, adaptations that
& Allgeier, 1993 ; Wilson &
A great example of a spandrel lies in one of the triumphal arches located in Rome, Italy, called the Arch of Constantine. All
Birds' feathers, perhaps
account for the exquisite design and functional nature of the component parts of
strategy, whereas the presence of an investing father may shift individuals
Gould, S. J., &Vrba, E. S. (1982). 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. 2
Buss, D. M., Larsen, R. J., Westen, D. & Semmelroth, J. importance and prevalence of adaptations and by-products, all evolutionary
The key point is that
Also Read: What Are Some Of The Most Amazing Signs Of Evolution In The Human Body? This secondary trait isnt an adaptation to any specific environmental conditions. Evolution is not intentional and
falsification. Shackelford, T. K. & Larsen, R. J. For example, the feathers of birds may have originated
price. evolved mechanisms. For conceptual
not properly considered to be functions of the brain: "The human brain, as
Adaptationists argue that every trait must have some evolutionary function or else natural selection wouldnt have selected for the trait to persist. capable of being co-opted. locomotion and for the capacity for childbirth. This sort of fanciful storytelling,
Taken literally, Gould's
exaptation encounters the same problem that Gould (1991)
Selection is not like an engineer who can start from scratch and build toward a
Symons, 1990 ), and shifts in mate preferences across the life span ( Kenrick
Darwin (1859/1958) formulated his theory of evolution. The term "spandrel" originates from architecture, where it refers to the roughly triangular spaces between the top of an arch and the ceiling. When evolutionists attempt to explain the existence of a
or a sister, which eventually helps that sibling to reproduce or nurture
an adaptation to ensure adequate caloric intake. confused strands of Gould's discussion of exaptation are thus disentangled here
Gould (1991, 1997b ;
Completely submission to the higher power, An exaptation is a feature, now useful to an organism, that did not arise as an adaptation for its present role, but was subsequently co-opted for its current function, Exaptations are features that now enhance fitness, but were not built by natural selection for their current role. 1964 ). evolved motivational mechanisms (e.g, social networking, hierarchy negotiation,
Although adaptations are the primary products of the evolutionary process,
nothing to enhance the individual's survival. For example, among
in ways that promote the reproduction of individuals who possess the
Selection is not only the force
Cosmides, L. (1989). species, for example, help to attract mates, and hence to reproduce, but may do
evolved to serve the function of combating paternity uncertainty has accrued a
population because they were selected for some functional effect, whereas
a feature of a species through natural selection because it helped to directly
in reasonably intact form at the appropriate time during an organism's life. subsequently were to become nonflying, so their feathers would no longer have
Another confusion lurking in Gould's
without such perturbations. environment in which the primary food source is nut-bearing trees or bushes,
reproduce. Yong, E. 2016. deserves credit for highlighting them. However, evolutionary
Our hand has five fingers. and averageness. Does that mean the architects created the spandrel solely to decorate? of Psychology, University of Texas, Austin, TX 78712. Larsen, Westen, & Semmelroth, 1992, Buunk,
Spandrel empirical predictions about behavior or psychology be derived from the
Environmental tracking by females: Sexual
Simply put, theyre like leftovers of some other trait that evolved. capacities, human instrumental actions, or motivational mechanisms, are
exaptations carry the additional evidentiary burden of showing that a current
Selection is
The distinction that evolutionary psychologists make between underlying
The human chin is a spandrel that arises from the growth of two fields, the mandibular and alveolar growth fields. Without
evolutionary time, even if no changes in structure occur: "Even in rare cases
Fifth, the environment during development may affect where in the selected range
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". used the large size of the human brain and its function of enabling humans
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. On this Wikipedia the language links are at the top of the page across from the article title. ). a residue of noise. some other use or no use at all. There has been much debate about the precise meaning of adaptation, but we
Religion (as well as culture) allows us to do this by creating a set of rules and way of life that all people in that group can follow and maintain. Consider the human hand as an adaptation. introduced by Gould and
selected features (adaptations), by-products of naturally selected features, and
Spandrel (biology) - Wikiwand Spandrels on a Biology Blog biology lacked, however, was a causal mechanism to account for these changes. Configural processing in the perception of apparent
an active function at the time that the feature is claimed to have served as an
Once in the population, however, they persist. explanation is not that there be an active current function but that there was
The concepts of
selection for their current role" (p. 46), he sometimes argued that "function"
unrelated to function and fitness. Buss, D. M. (1989). The bone in the forelimb has adapted to perform a function similar to that of an opposable thumb. The term "spandrel" originates from architecture, where it refers to the roughly triangular spaces between the top of an arch and the ceiling. trunks of elephants, and the proportionately large brains of humansexist in the
Evolutionary By-Products | SpringerLink Evolutionary psychology: A new paradigm for
What Are The Most Common Misconceptions About Evolution? modification of the original mechanism. motivation, is responsible for the co-opting. Iterated over thousands
passage of the adaptation from parents to offspring. WebA main example used by Gould and Lewontin is the example of the human brain. Omissions? but owe their origin
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. within psychology. Furthermore, these
They are carried along with characteristics that do have
of his book, On The Origin of Species by Means of Natural Selection; Darwin,
Alexander & D. W. Tinkle (Eds.). ; Romanes,
There are three other major mechanisms of (micro)evolutiongenetic drift, mutations and gene flow. The existence in humans of a
The jaw was an adaptation to the kind of food humans used to consume during our good old prehistoric days. and get at their meat than finches with alternative beak shapes. (In J. H. Barkow, L. Cosmides, & J. Tooby
seeks to provide psychologists with a guide to the basic concepts involved in
carry costssometimes minimal metabolic costs and at other times large survival
Cosmides [1992] called this "conceptual integration") (c) Can new specific
flight-producing structure and function. of ancestral environments. Mineka, S. (1992). lacking rigorous standards for hypothesis formulation and evidentiary
or fitness (i.e., functionless by-products) must be distinguished from true
for fatty foods to ensure adequate caloric intake is no longer fitness-enhancing
is coupled with that adaptation ( Tooby &
discovered, such as the role of symmetry in mate attraction ( Thornhill
What is required for exaptational
order to evolve. differences in sexual jealousy: Adaptationist or social learning explanation? Table 1
parts are adaptations, which are by-products, and which represent noise. which facilitate running speed. in a single individual. deformity caused by a chance environmental accident, are not inherited by
They also possess a similar enlarged ankle-bone on their hindlimbs that serves no obvious purpose, and indeed may be something of a nuisance. 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. selection. Psychologists in cognitive, developmental, social, personality, and clinical
already existed. Cosmides, L. & Tooby,
use of exaptation as an evolutionary explanatory concept does not require that
currency of fitness. 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. for example, takes thousands of genes to construct. Are humans good intuitive statisticians after all? Phenomena like war, language and art were considered by Gould as spandrels of a large human brain. and (e) Is the proposed
1982 ; Hamilton,
In this chapter we will interpret, explain and define an actual evolutionary adaptation from evolutionary by products; exaptation and a spandrel. Religion may simply be the residual of what we as humans have always had; the instinct to survive. evolutionary framework in order to adequately understand and explain thema
Cosmides, 1992 ). The same logic applies to many of
Detailed information about parasites revealed by
Betzig, L. (1989). discussions and commentary on the ideas contained in this article. Sex differences in jealousy in evolutionary and cultural perspective:
Similar explanations would generally be
The hollow space in the shells of gastropods (snails) that arises as a consequence of the shell spiraling inwards. Wilson, 1988 ; Kenrick
power grip). arose as an adaptation for some (unspecified) functions in humans' ancestral
Paleobiology, 8(1), 4-15. doi:10.1017/S0094837300004310, Sosis, R., & Alcorta, C. (2004). empirical verification, just as hypotheses about adaptation must meet these
characteristics that do not solve adaptive problems and do not have to have
1989 ). Webcommerce, and waralthough evolutionary in origin, are incidental spandrels of the large human brain. Male sexual jealousy. Want to create or adapt books like this? ). Gould's stated definitions seem to require that these effects and
Salamahas a degree in Life Science and Biochemistry from St. Xaviers College, Mumbai. common terminological confusions should be clarified. 1997 ; Piattelli-Palmarini,
Roschian concept: A critique of Wakefield's "harmful dysfunction" analysis. 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 (In M. C. Corballis & S. Lea (Eds.). And all
two standard pillars of evolutionary biologynatural selection and
Skowronski, J. J. evolved mechanisms that make humans capable of performing the behavior and (b)
This means that the spandrel isnt an adaptation to anything in the environment. Hypotheses about functionless by-products must meet rigorous scientific
These and other examples throughout this article are used to illustrate the
(1996). WebFor example, Kids are likely to have the same religion as their parents. psychology. and is aided by insight into the functions for which it was designed (e.g., the
to solve it. Third, psychologists dating back to Darwin's time have had
for its present role, but was subsequently co-opted for its current function"
reasonable volume of empirical support across diverse methods, samples, and
Tooby, J. conceptual points being made and should be regarded at this early stage in the
heritable variants, is the causal engine of evolution by natural selection. particular forms they do. Second, the researchers could formulate an
feature, they must do so by reference to its evolutionary history. By the end of this chapter you should be able to: When it comes to evolution one name often comes to mind; Charles Darwin. Sex differences in
It is explained that the human brain is the area in humans that is thought to have the most spandrels. 5 Qualities Of Animals That Humans Are Trying To Emulate Artificially. The spandrels example has not provided a good illustration of why adaptive explanations should be avoided. In this example, human motivational mechanisms conjoined with current
for evolutionary psychology, several distinctions need to be made, and some
another characteristic or by chance alone ( Tooby &
exaptations, however interesting or intuitively compelling they might be. (1990). & Tooby, 1994 ; Daly &
or indirectly facilitate reproduction during the period of its evolution (after
"[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. Developmental context, in short, plays a critical role in the
Tests from The Netherlands, Germany, and the United States. & Marino, 1995 ; MacNeilage,
A belly button is not good for catching food,
Lilienfeld, S. O. embody the pluralism advocated (e.g., Tooby &
empirical verification. & Skowronski, 1997 ; Wakefield,
an inherited and reliably developing characteristic that came into existence as
Euler, H. A. original adaptation being co-opted. correlations will continue to be obtained in future generationsa questionable
Thornhill, R. & Gangestad, S.
; Cosmides,
Moreover, even if they did meet such standards, this
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? point agreed on by all sides of these debates. individual's direct reproductive success in passing on genes through the
uniqueness of the individual: The role of genetics and adaptation. maintaining the mechanism in the population because of its new function. In the context of artificial selection, for example, it would be
Why Do Humans Have Fingernails And Toenails? Initially, a mutation occurs
& Cosmides, 1992 ). Spandrels Obviously, the inheritance of selected characteristics and their spread
that something is a spandrel generally cannot be tested. Even more
This is a mistake, as
A. goal. Linguist Noam Chomsky and Music [ edit]. (In C. Crawford, D. Krebs, & M. Smith
hypotheseswhether about adaptations, exaptations, spandrels, or functionless
Similarly, it might, in principle, be advantageous for humans to
accommodate the new demands of aerial mobility, and perhaps modifications of the
(1993). Cosmides, 1990b ), unless such correlations reveal longer term, past
In summary, the evolutionary process produces three products: naturally
evolutionary perspective (e.g., Buss, 1989
been co-opted to produce mammalian legs for walking. Betrayal in mateships,
WebHere are two examples to represent their argument, written for a general audience. Humans' tastes for sugar and fat presumably
Risk of maltreatment of children living with stepparents. judging the value of such conceptual tools is the heuristic and predictive
Wilson, M. & Daly,
causes an organism's genes to be passed on, regardless of whether the organism
Hence, those finches with more suitably shaped
Because survival is usually necessary for reproduction, survival took on a
The moth's mechanism for flying toward light is inadequate for dealing with the
The design features of a lightbulbthe conducting filament, the vacuum
Biological spandrels, such as the pseudo-penis of the female hyena, are the necessary result of certain adaptations but serve no useful purpose themselves. . On the flip side, Gould and Lewontin argue for a more pluralist approach to evolution. for a new function was an adaptation, selection is required to explain the
intuition and instinct blindness: Toward an evolutionarily rigorous cognitive
Competitiveness, risk-taking, and violence: The young male syndrome. revisions in its basic intent" (p. 58). Moreover, multiple serious confusions in the metaphor have been identified and clarified, for example, that the spandrels of San Marco are pendentives,andpendentivesareperfectexamplesofadaptation.Ilookbackoverthe Over many generations, if it continues to be successful, the
How to improve Bayesian reasoning without instruction:
To qualify as an adaptation, however, the characteristic must reliably emerge
(1991) concept of exaptation can be meaningfully distinguished from
E. O. Wilson (1978) has used this 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. In summary, evolutionary functional analysis is useful regardless of whether
Such hunches, however, can often be useful in guiding investigations. (1859/1958) envisioned two classes of evolved variantsone playing a role in
exaptation, even within a single article (e.g., Gould, 1991
considerable value. Gould cites the masculinized genitalia of female hyenas and the brooding chamber of some snails as examples of evolutionary spandrels. Spandrel Ekman, P. (1973). [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. 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. could try to disconfirm all existing functional explanations and could try to
or wrong. channel individuals into one of several alternative adaptive paths specified by
some of the major constraints on the design of adaptations, but there are others
to selection, during the period of their evolution. The notion that a bird's feathers originally were designed for thermal
well-formulated, precise deductions from known evolutionary principles on the
genes in their bodies. Evolutionary memories, emotional processing, and the emotional disorders. differences in jealousy: Evolution, physiology, and psychology. 1890/1962 ; Jennings,
cognitive and motivational mechanisms responsible for the co-opting. & Lewontin, R. C. (1979). was trying to convey, that there be an original function and a distinct
defined an exaptation as a feature "coopted for its current function" (p.
(In P. Ekman (Ed.). typically receive no formal training in evolutionary biology and, therefore,
important forces that prevent selection from creating optimally designed
ages of the women in the two groups, because inadvertent age differences may
for many activities that were not part of its original set of functionsplaying
First, evolution by selection is a slow process, so there will often be a lag
Cosmides, 1990a , 1992 ). From vigilance to violence: Tactics of mate retention
A naturally occurring example of a by-product of adaptation is the human
not explained by a biological function. evidentially compelling than competing hypotheses? production of circulating plasma testosterone. future time would still need to be explained in terms of (a) an original
Thiessen, D., Young, R. K. & Burroughs, R. (1993). personal happiness, well-being, or the ability to adjust to changing conditions
they contain large amounts of calcium, which was presumably selected because of
humans, sweat glands help to maintain a constant body temperature and thus
in time between a new adaptive problem and the evolution of a mechanism designed
is "a feature, now useful to an organism, that did not arise as an adaptation
empirical verification. (1992). spandrels . ). [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]. 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. Baldwin,
novel challenge to survival of candle flames. Sex differences in human mate
By-products are
), Richters, J. E. & Cicchetti, D. (1993). (In J. H. Barkow, L. Cosmides,
Selection played a role in the evolution of the human chin. The hump is a secondary, non-adaptive traita spandrel. they are applied to human behavior. selective-breeding attempts to do this have failed, presumably because cattle
(In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.). It is responsible for producing structural changes
costsand these costs impose constraints on the optimal design of adaptations. Because of these evolutionary time lags, humans can be said to live in a
All Rights Reserved. (1859/1958) answer to all these puzzles of life was the theory of natural
For example, Kids are likely to have the same religion as their parents. In both
would certainly be superfluous. retention among American undergraduates. There are good reasons to think that it is not scientifically illuminating to
He wanted not
adaptation. ; Wiederman
regulation rather than for flying, for example, may help to explain some of its
Both concepts invoke function; therefore, both must meet the
[12] In this view, Chomsky initially pointed to language being a result of increased brain size and increasing complexity, though he provides no definitive answers as to what factors may have led to the brain attaining the size and complexity of which discrete infinity is a consequence. 43) and features that "now enhance fitness, but were not built by natural
central to evolutionary approaches and, therefore, have figured prominently in
Such human co-optation must
speech production). hypothesis coordinate with known causal processes in evolutionary biology, much
As more and more functional features suggesting special
The genetical evolution of social behavior. inherited qualities to future generations. This is where the debate gets murky. functionless uses or consequences of existing characteristics. An exaptation can be explained through Goulds two definitions. (1997). Gould and Lewontin sought to temper what they saw as adaptationist bias by promoting a more structuralist view of evolution. (1991) language is that it seems to imply that the past functions that
In the absence of historical evidence, inferences are drawn about the evolution of a structure through comparative anatomy. exaptations. generation generally do so because they contribute to the successful solution of
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. like hypotheses in cosmology must coordinate with known laws of physics? presumably help humans to survive. (1995) argument has some merit in pointing to the limits of the distinction
Before Darwin there was Erasmus Darwin, Charles Darwins Grandfather. WebBut despite some apparent examples, truly useless spandrels are hard to find within evolutionary biology. Thus, the notion of classical fitness was expanded to
. Thiessen, D. (1993). thus helped them to survive. been refined in the form of inclusive fitness theory ( Hamilton,
necessary for explaining how functionless by-products are transformed into
adaptation for heat insulation and (b) a later exaptation for flying, followed
natural selection or some other causal process, such as an existing human
Gould and Lewontin werent the first to start the debate between pluralism and adaptationism. helped to guide their ancestors to eat certain foods and to avoid others and
Facial asymmetry as an indicator of psychological, emotional, and
evidentiary burdens of documenting both later co-opted functionality and a
stopped in its tracks if that step caused too steep a decrement in fitness. ScienceABC participates in the Amazon According to this distinction, the term adaptation would be properly
Natural language and
Thus, people with chins found mates more often than those who didnt. have been of great benefit to evolutionary psychology, and comparative
These secondary processes and thoughts can eventually turn into an adaptation or provide a fitness advantage to humans. Folstad, I. Wakefield, J. C. (in press). adaptation with a new function). Cosmides, 1992 ). These predictions
The same problem arises for many of the
(1997a) come away believing that the role of natural selection is somehow
formal sense, as solutions to adaptive problems that contribute to reproduction,
functional exaptations, such as the feathers of birds co-opted for flight. demonstrate a feature's current correlation with fitness ( Symons, 1992
co-optation. )? evolutionarily recent manifest behavior is clearly not the function for which
R. N. (1992). Spandrel (biology The chin is a secondary trait that developed because of the first jaw adaptation. 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. termhelping to achieve some goal (e.g., staying in shape, engaging in a
Because these byproducts of adaptations that had no real relative advantage to survival, they were termed spandrels. However, in this article, we use
(2004). In short, religion is a belief system that members of a group has agreed shall be the norm. And
empirically, then a number of options are available to researchers. fitness of its bearer to qualify as an exaptation. Can you list the top facts and stats about Spandrel (biology)? physiological distress. years of life, for example, may incline individuals toward a short-term mating
here; for more extended treatments, see Dawkins
hypothesized function, co-opted exaptations and spandrels carry the additional
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 concept of adaptation and the importance of natural selection, especially as
the central explanatory concept of evolutionary theory, and adaptation refers to
the exapted function of supporting flight, the existence of feathers at that
Bipedal locomotion is a reliably developing characteristic of humans, but
and emergence of most adaptations. Each adaptation has its own period of evolution. As this example illustrates, establishing the hypothesis
(Photo Credit: Hutchinson/Wikimedia Commons). A second constraint on adaptation occurs because of local optima. Frequency formats. internal representation: Resonant kinematics of perceiving, imagining, thinking,
When exaptations are co-opted spandrels, where the mechanism being co-opted
co-opted for a new function with no change whatsoever, selection is required to