Koinophilia
Encyclopedia
Koinophilia is a term used by biologist
Johan Koeslag, meaning that when sexual creatures seek a mate, they prefer that mate not to have any unusual, peculiar or deviant features.
Natural selection
results, over the course of generations, in beneficial (or "fit"
) features replacing their disadvantageous counterparts. Thus, natural selection causes beneficial features to become increasingly more common with each generation, while the disadvantageous features become increasingly rare. A sexual creature, therefore, wishing to mate with a fit partner, would be expected to avoid individuals sporting unusual features, while being especially attracted to those individuals displaying a predominance of common or average features
. This is termed "koinophilia". It has, as an important side effect, that mates displaying mutant features (the result of a genetic mutation
) are also avoided. This, in itself, is also advantageous, because the vast majority of mutations that manifest themselves as changes in appearance, functionality or behavior, are disadvantageous. Because it is impossible to judge whether a new mutation is beneficial or not, koinophilic creatures will avoid them all with equal determination, even if this means avoiding the very occasional beneficial mutation. Thus, koinophilia, although not perfect or infallible in its ability to distinguish fit
from unfit mates, remains, on average, a very good strategy when choosing a mate
. It will be right far more often than it will be wrong. Even when it is wrong, a koinophilic choice always ensures that the offspring will inherit a suite of thoroughly tried and tested features.
According to Koeslag, koinophilia provides very simple and obvious explanations for such evolutionary puzzles as the process of speciation
, evolutionary stasis and punctuated equilibria
, and the evolution of cooperation
. Koinophilia might also contribute, possibly substantially, to the maintenance of sexual reproduction, preventing its reversion to the much simpler and inherently more advantageous asexual form of reproduction
.
, was first referred to as koinophilia by Johan H. Koeslag, from the Greek, koinos, meaning "the usual" or "common", and philos, meaning "fondness" or "love". It was independently identified in humans by Judith Langlois and her coworkers, who found that the average of two human faces was more attractive than either of the faces from which that average was derived. The more faces (of the same gender and age) that were used in the averaging process
the more attractive and appealing the average face became.
, a half cousin of Charles Darwin
, created composite portraits of a number of convicted criminals, hoping to generate a prototypical criminal face. Surprisingly, the composite portrait became more and more attractive with the addition of each new face. Galton published this rather inexplicable finding in 1878, concluding that average features combine to create good-looking faces.
Despite of the novelty of this finding, Galton’s observations were forgotten till Judith Langlois and Lori Roggman created computer generated composite images. They found that facial attractiveness increased in proportion to the number of faces that went into creating the composite. Many studies, using different averaging techniques, including the use of line drawings and face profiles, have subsequently shown that this is a general principle: average faces are consistently more attractive than the faces used to generate them.
This principle transcends culture. For instance, Coren Apicella and her co-workers from Harvard University created average faces of an isolated hunter-gatherer tribe in Tanzania of Africa. These Hazda people rated the average Hazda faces as more attractive than the actual faces in the tribe. While Europeans also rated average Hazda faces as attractive, the Hazda people did not express any preference for average European faces. Apicella attributes this difference to the visual experiences of the Europeans and the Hazda tribes people. While the Hazda had never been exposed to human races outside their immediate environment, the Europeans had been exposed to both Western and African faces. Thus the indifference of the Hazda towards average European faces could have been the result of lacking the European ‘norm’ in their visual experience. These results suggest that the rules for extracting attractive faces are culture-independent and innate, but the results of applying the rules depend on the environment and cultural experience.
That the preference for the average is biological rather than cultural has been supported by a number of studies on babies. Neonates and infants gaze longer at attractive faces than at unattractive faces.
Furthermore, Mark Stauss reported that 10-month old children respond to average faces in the same way as they respond to attractive faces, and that these infants are able to extract the average from simply drawn faces consisting of only 4 features. Adam Rubenstein and coworkers showed that already at six months of age, children not only treat average faces the same as they treat attractive faces, but they are also able to extract the central tendency (i.e. the average) from a set of complex, naturalistic faces presented to them (i.e. not just the very simple 4-features faces used by Strauss). Thus the ability to extract the average from a set of realistic facial images operates from an early age, and is therefore almost certainly instinctive.
Despite these findings, David Perrett and his colleagues at St Andrews University in Scotland found that both men and women considered that a face averaged from a set of attractive faces was more appealing than one averaged from a wide range of women's faces. When the differences between the first face and the second face were slightly exaggerated the new face was judged, on average, to be more attractive still. However, the three faces are difficult to distinguish one from the other, although close examination shows that the so-called “exaggerated face” looks slightly younger than the average face (composed of women's faces aged 22–46 years). Since the same results were obtained using Japanese subjects and viewers, these findings are probably culture-independent; indicating that people generally find youthful average faces sexually the most attractive. (European viewers saw no differences between the three female Japanese faces created by David Perrett.)
produces groups of individuals, labeled species
, whose adult members look extraordinarily similar, and distinctively different from the members of other species. Lions and leopards are, for instance, both large carnivores inhabiting the same general environment, and hunting much the same prey, in much the same way, but they look extraordinarily different, and would not be confused one for the other even by the most unsophisticated observer. There would seem to be no obvious evolutionary reason which suggests that lion-leopard intermediates are likely to be less successful hunters than either of the two distinct species that inhabit the African savanna today. Why then do they not exist? What evolutionary force drives these intermediate forms to extinction, leaving only highly uniform and distinctive lions on the one hand and highly uniform and distinctive leopards on the other?
This is, however, only one aspect of what is almost certainly a two-dimensional problem. The "horizontal" dimension refers to the almost complete absence of transitional, or intermediate forms between present-day species (e.g. between lions, leopards, cheetahs and lynxes). The "vertical" dimension concerns the fossil record. Fossil species are frequently remarkably stable over extremely long periods of geological time, despite continental drift, major climate changes, and mass extinctions. When a change in appearance or form does occur, it tends to be abrupt in geological terms, again producing phenotypic gaps (i.e. an absence of intermediate forms), but now between successive species, which then often co-exist for considerable periods of time. Thus the fossil record, though open to different interpretations, suggests that evolution occurs in bursts, interspersed by long periods of evolutionary stagnation (i.e. by means of punctuated equilibria
). Why this is so, has been one of evolution's great mysteries.
Koinophilia could explain both the horizontal and vertical manifestations of speciation, and why it usually involves the entire external appearance of the creatures concerned. If sexual creatures prefer mates sporting predominantly common features, and avoid mates with unusual, unfamiliar, fringe, or extreme attributes, then common features will tend to become more common still, and at a rate and to an extent that natural selection on its own is unlikely to achieve. Since koinophilia affects the entire external appearance, the members of an interbreeding group will soon all begin to look astoundingly alike, both with regard to important or essential features (e.g. the jaws, dentition, and claws of a lion) and trivial features (e.g. the black furry tuft at the tip of the lion’s tail, or the lion's “beard”) . It is almost inevitable that each interbreeding group will, in this way, very quickly develop its own characteristic appearance. An individual from one group who wanders into another group will consequently be recognized as being different, and will, therefore, be discriminated against during the mating season. This koinophilia-induced reproductive isolation might thus be the first crucial step in the development of, ultimately, physiological, anatomical and behavioral barriers to hybridization, and thus, ultimately, full specieshood. Koinophilia will thereafter defend that species' appearance and behavior against invasion by unusual or unfamiliar forms (which might arise by immigration or mutation), and thus be a paradigm of punctuated equilibria
(or the "vertical" aspect of the speciation problem.), and stabilizing selection
.
Cooperation is any group behavior that benefits the individuals more than if they were to act as independent agents. There is, however, a second, very important, corollary to cooperation: it can always be exploited by selfish individuals who benefit even more by not taking part in the group activity, yet reaping its benefits. For instance, a selfish individual who does not join the hunting pack and its incumbent dangers but nevertheless shares in the spoils has a fitness advantage over the other members of the pack. Thus, although a group of cooperative individuals is fitter than an equivalent group of selfish individuals, selfish individuals interspersed amongst a community of cooperators are always fitter than their hosts. This means they raise, on average, more offspring and grandoffspring than their hosts, and will therefore ultimately replace them.
If, however, the selfish individuals are ostracized, and rejected as mates, because of their deviant and unusual behavior, then their evolutionary advantage becomes an evolutionary liability. Cooperation in all of its very many forms then becomes evolutionarily stable
. Sociability, social conventions, ritualistic behavior, the expressions of the emotions, and other forms of communication between individuals, all essential ingredients for full cooperativity, can all be similarly evolutionarily stabilized
by koinophilia.
.
.
.
.
.
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
Johan Koeslag, meaning that when sexual creatures seek a mate, they prefer that mate not to have any unusual, peculiar or deviant features.
Natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
results, over the course of generations, in beneficial (or "fit"
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
) features replacing their disadvantageous counterparts. Thus, natural selection causes beneficial features to become increasingly more common with each generation, while the disadvantageous features become increasingly rare. A sexual creature, therefore, wishing to mate with a fit partner, would be expected to avoid individuals sporting unusual features, while being especially attracted to those individuals displaying a predominance of common or average features
Averageness
In attractiveness studies, averageness is one of the characteristics of physical beauty in which the average phenotype, i.e. outward appearance, of the individual theoretically characterizes averaged genotypes, thus indicating health and fertility. The majority of averageness studies and theories...
. This is termed "koinophilia". It has, as an important side effect, that mates displaying mutant features (the result of a genetic mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
) are also avoided. This, in itself, is also advantageous, because the vast majority of mutations that manifest themselves as changes in appearance, functionality or behavior, are disadvantageous. Because it is impossible to judge whether a new mutation is beneficial or not, koinophilic creatures will avoid them all with equal determination, even if this means avoiding the very occasional beneficial mutation. Thus, koinophilia, although not perfect or infallible in its ability to distinguish fit
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
from unfit mates, remains, on average, a very good strategy when choosing a mate
Sexual selection
Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection...
. It will be right far more often than it will be wrong. Even when it is wrong, a koinophilic choice always ensures that the offspring will inherit a suite of thoroughly tried and tested features.
According to Koeslag, koinophilia provides very simple and obvious explanations for such evolutionary puzzles as the process of speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
, evolutionary stasis and punctuated equilibria
Punctuated equilibrium
Punctuated equilibrium is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis...
, and the evolution of cooperation
Co-operation (evolution)
Co-operation or co-operative behaviours are terms used to describe behaviours by organisms which are beneficial to other organisms, and are selected for on that basis. Under this definition, altruism is a form of co-operation in which there is no direct benefit to the actor...
. Koinophilia might also contribute, possibly substantially, to the maintenance of sexual reproduction, preventing its reversion to the much simpler and inherently more advantageous asexual form of reproduction
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
.
Introduction
This mating strategySexual selection
Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection...
, was first referred to as koinophilia by Johan H. Koeslag, from the Greek, koinos, meaning "the usual" or "common", and philos, meaning "fondness" or "love". It was independently identified in humans by Judith Langlois and her coworkers, who found that the average of two human faces was more attractive than either of the faces from which that average was derived. The more faces (of the same gender and age) that were used in the averaging process
Averageness
In attractiveness studies, averageness is one of the characteristics of physical beauty in which the average phenotype, i.e. outward appearance, of the individual theoretically characterizes averaged genotypes, thus indicating health and fertility. The majority of averageness studies and theories...
the more attractive and appealing the average face became.
Physical attractiveness
Francis GaltonFrancis Galton
Sir Francis Galton /ˈfrɑːnsɪs ˈgɔːltn̩/ FRS , cousin of Douglas Strutt Galton, half-cousin of Charles Darwin, was an English Victorian polymath: anthropologist, eugenicist, tropical explorer, geographer, inventor, meteorologist, proto-geneticist, psychometrician, and statistician...
, a half cousin of Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
, created composite portraits of a number of convicted criminals, hoping to generate a prototypical criminal face. Surprisingly, the composite portrait became more and more attractive with the addition of each new face. Galton published this rather inexplicable finding in 1878, concluding that average features combine to create good-looking faces.
Despite of the novelty of this finding, Galton’s observations were forgotten till Judith Langlois and Lori Roggman created computer generated composite images. They found that facial attractiveness increased in proportion to the number of faces that went into creating the composite. Many studies, using different averaging techniques, including the use of line drawings and face profiles, have subsequently shown that this is a general principle: average faces are consistently more attractive than the faces used to generate them.
This principle transcends culture. For instance, Coren Apicella and her co-workers from Harvard University created average faces of an isolated hunter-gatherer tribe in Tanzania of Africa. These Hazda people rated the average Hazda faces as more attractive than the actual faces in the tribe. While Europeans also rated average Hazda faces as attractive, the Hazda people did not express any preference for average European faces. Apicella attributes this difference to the visual experiences of the Europeans and the Hazda tribes people. While the Hazda had never been exposed to human races outside their immediate environment, the Europeans had been exposed to both Western and African faces. Thus the indifference of the Hazda towards average European faces could have been the result of lacking the European ‘norm’ in their visual experience. These results suggest that the rules for extracting attractive faces are culture-independent and innate, but the results of applying the rules depend on the environment and cultural experience.
That the preference for the average is biological rather than cultural has been supported by a number of studies on babies. Neonates and infants gaze longer at attractive faces than at unattractive faces.
Furthermore, Mark Stauss reported that 10-month old children respond to average faces in the same way as they respond to attractive faces, and that these infants are able to extract the average from simply drawn faces consisting of only 4 features. Adam Rubenstein and coworkers showed that already at six months of age, children not only treat average faces the same as they treat attractive faces, but they are also able to extract the central tendency (i.e. the average) from a set of complex, naturalistic faces presented to them (i.e. not just the very simple 4-features faces used by Strauss). Thus the ability to extract the average from a set of realistic facial images operates from an early age, and is therefore almost certainly instinctive.
Despite these findings, David Perrett and his colleagues at St Andrews University in Scotland found that both men and women considered that a face averaged from a set of attractive faces was more appealing than one averaged from a wide range of women's faces. When the differences between the first face and the second face were slightly exaggerated the new face was judged, on average, to be more attractive still. However, the three faces are difficult to distinguish one from the other, although close examination shows that the so-called “exaggerated face” looks slightly younger than the average face (composed of women's faces aged 22–46 years). Since the same results were obtained using Japanese subjects and viewers, these findings are probably culture-independent; indicating that people generally find youthful average faces sexually the most attractive. (European viewers saw no differences between the three female Japanese faces created by David Perrett.)
Speciation and "punctuated equilibria"
A major evolutionary problem has been how the continuous process of evolutionEvolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
produces groups of individuals, labeled species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, whose adult members look extraordinarily similar, and distinctively different from the members of other species. Lions and leopards are, for instance, both large carnivores inhabiting the same general environment, and hunting much the same prey, in much the same way, but they look extraordinarily different, and would not be confused one for the other even by the most unsophisticated observer. There would seem to be no obvious evolutionary reason which suggests that lion-leopard intermediates are likely to be less successful hunters than either of the two distinct species that inhabit the African savanna today. Why then do they not exist? What evolutionary force drives these intermediate forms to extinction, leaving only highly uniform and distinctive lions on the one hand and highly uniform and distinctive leopards on the other?
This is, however, only one aspect of what is almost certainly a two-dimensional problem. The "horizontal" dimension refers to the almost complete absence of transitional, or intermediate forms between present-day species (e.g. between lions, leopards, cheetahs and lynxes). The "vertical" dimension concerns the fossil record. Fossil species are frequently remarkably stable over extremely long periods of geological time, despite continental drift, major climate changes, and mass extinctions. When a change in appearance or form does occur, it tends to be abrupt in geological terms, again producing phenotypic gaps (i.e. an absence of intermediate forms), but now between successive species, which then often co-exist for considerable periods of time. Thus the fossil record, though open to different interpretations, suggests that evolution occurs in bursts, interspersed by long periods of evolutionary stagnation (i.e. by means of punctuated equilibria
Punctuated equilibrium
Punctuated equilibrium is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis...
). Why this is so, has been one of evolution's great mysteries.
Koinophilia could explain both the horizontal and vertical manifestations of speciation, and why it usually involves the entire external appearance of the creatures concerned. If sexual creatures prefer mates sporting predominantly common features, and avoid mates with unusual, unfamiliar, fringe, or extreme attributes, then common features will tend to become more common still, and at a rate and to an extent that natural selection on its own is unlikely to achieve. Since koinophilia affects the entire external appearance, the members of an interbreeding group will soon all begin to look astoundingly alike, both with regard to important or essential features (e.g. the jaws, dentition, and claws of a lion) and trivial features (e.g. the black furry tuft at the tip of the lion’s tail, or the lion's “beard”) . It is almost inevitable that each interbreeding group will, in this way, very quickly develop its own characteristic appearance. An individual from one group who wanders into another group will consequently be recognized as being different, and will, therefore, be discriminated against during the mating season. This koinophilia-induced reproductive isolation might thus be the first crucial step in the development of, ultimately, physiological, anatomical and behavioral barriers to hybridization, and thus, ultimately, full specieshood. Koinophilia will thereafter defend that species' appearance and behavior against invasion by unusual or unfamiliar forms (which might arise by immigration or mutation), and thus be a paradigm of punctuated equilibria
Punctuated equilibrium
Punctuated equilibrium is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis...
(or the "vertical" aspect of the speciation problem.), and stabilizing selection
Stabilizing selection
-Description:Stabilizing or ambidirectional selection, , is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. This is probably the most common mechanism of action for natural selection...
.
The evolution of cooperation
If, however, the selfish individuals are ostracized, and rejected as mates, because of their deviant and unusual behavior, then their evolutionary advantage becomes an evolutionary liability. Cooperation in all of its very many forms then becomes evolutionarily stable
Evolutionarily stable strategy
In game theory and behavioural ecology, an evolutionarily stable strategy , which is sometimes also called an evolutionary stable strategy, is a strategy which, if adopted by a population of players, cannot be invaded by any alternative strategy that is initially rare. An ESS is an equilibrium...
. Sociability, social conventions, ritualistic behavior, the expressions of the emotions, and other forms of communication between individuals, all essential ingredients for full cooperativity, can all be similarly evolutionarily stabilized
Evolutionarily stable strategy
In game theory and behavioural ecology, an evolutionarily stable strategy , which is sometimes also called an evolutionary stable strategy, is a strategy which, if adopted by a population of players, cannot be invaded by any alternative strategy that is initially rare. An ESS is an equilibrium...
by koinophilia.
.
.
.
.
.
External links
- Why Sex? discusses the origin of sex, and the evolutionary problem of the affordability of males, together with its koinophilic solution.
- http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WMD-45S96TH-5-1&_cdi=6932&_user=613892&_orig=search&_coverDate=12%2F21%2F1995&_sk=998229995&view=c&wchp=dGLbVzb-zSkzS&md5=5ca90c43829c1ac4503e69973e9de576&ie=/sdarticle.pdf J. Theor. Biol. (1995) article entitled "On the engine of speciation"
- http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WMD-491BYXG-5&_coverDate=10%2F07%2F2003&_alid=109914822&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6932&_sort=d&view=c&_acct=C000032099&_version=1&_urlVersion=0&_userid=613892&md5=307073e49eb8b5c28621efc7fea4d8fb J. Theor. Biol. (2003) article entitled "Evolution of cooperation: cooperation defeats defection in the cornfield model"
- Beauty Check includes example blended faces and discusses why average face shapes are more attractive.
- Averaging faces shows how the average of two faces looks more attractive than either of the faces used in the averaging process.
- Judith Langlois averages faces, starting with two faces, ending with a composite of 32 faces