Pair choice , also known as intersexual selection , is an evolutionary process whose selection depends on the appeal of individual phenotypic features. Evolutionary change is possible because the desired qualities in pairs are more often passed on to each generation over time. For example, if female peacocks want couples with colorful feathers, then this trait will increase over time as male peacocks with colorful feathers will have more reproductive success.
The choice of pair is one of the two components of sexual selection, the other is intrasexual selection. The ideas about sexual selection were first introduced in 1871, by Charles Darwin, later expanded by Ronald Fisher in 1915. Currently, there are five mechanisms that explain how spouse's choice has evolved over time. These are the direct phenotypic benefits, the sensory bias, the Fisher's runaway hypothesis, the characteristics of the indicator and the genetic compatibility.
In systems where spouse choice exists, one sex competes with same-gender members and the other is voter (which means they are selective when it comes to picking up others). There are direct and indirect benefits of being selective individuals. In most species, women are the voting sex that differentiates competitive men, but there are some examples of the inverted role (see below). It is preferable for an individual to choose suitable pairings of the same species, to maintain reproductive success. Other factors that may affect partner choice include pathogen stress and Major Histocompatibility Complex (MHC).
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Charles Darwin first expressed his ideas about sexual selection and the choice of spouse in his book The Descent of Man, and Selection in Relationships for Sex in 1871. He was puzzled by the intricate ornaments possessed by several species, because such features appear to be detrimental to survival and have negative consequences for reproductive success. Darwin proposed two explanations for the existence of such traits: they are useful in men's combat or they are favored by women. This article focuses on the latter. Darwin treated natural selection and sexual selection as two different topics, although in the 1930s biologists defined sexual selection as part of natural selection.
In 1915, Ronald Fisher wrote papers on the evolution of women's preferences and secondary sexual characteristics. Fifteen years later, he expanded the theory in a book called The Genetical Theory of Natural Selection. There he illustrates scenarios where feedback between pairing preferences and properties produces complex characters such as the long tail of a male peacock (see Fisherman's escape).
In 1948, using Drosophila as a model, Angus John Bateman presented experimental evidence that male reproductive success was limited by the number of pairs obtained, while the reproductive success of women was limited by the number of pregnancies he could have. in his lifetime. Thus a woman must be selective when choosing a partner because the quality of her offspring depends on her. Men must struggle, in the form of intra-sexual competition, for the opportunity to marry because not all men will be chosen by women. This is known as the Bateman principle, and although this is a major finding added to Darwin and Fisher's work, it was ignored until George C. Williams emphasized its importance in the 1960s and 1970s.
In 1972, soon after Williams revived the subject, Robert L. Trivers presented his parents investment theory. Trivers defines a parent's investment as any investment made by a parent who benefits his or her current child at the cost of investing in future offspring. These investments include the cost of generating gametes as well as the care or other efforts that parents provide after birth or hatching. Reformulating Bateman's ideas, Trivers argues that sexes that show less investment of parents (not necessarily men) will have to compete for opportunities to mate with sex that invests more. Different levels of parental investment create conditions that support matchmaking bias.
Maps Mate choice
Direct and indirect benefits
Being picky (having bias in the context of mating) should have a fitness advantage in order for this behavior to flourish. Two types of fitness benefits (direct and indirect) are thought to encourage the coupling mechanism of evolution of partners:
- The immediate benefits of enhancing preferred sex fitness through excellence or direct resources. These benefits include but are not limited to improving the quality of the area, improving parental care, and protection from predators. There is a great deal of support for the maintenance of couples with direct benefits and this approach offers the most controversial model for explaining discriminating marriages.
- Indirect benefits increase genetic fitness for offspring, and thus improve the inclusive fitness of the elderly. When it appears that voter sex does not receive direct benefits from their partners, indirect benefits can be selective. These indirect benefits may include high-quality genes for their offspring (known as indirect adaptive benefits) or genes that make their offspring more attractive (known as arbitrary indirect benefits).
Mechanism
Currently, there are five mechanisms that explain the evolution of partner choice:
- Direct phenotypic benefits
- Sensory bias
- Running fisherman
- The indicator character
- Genetic compatibility
Direct and/or indirect benefits encourage the mating bias described in each mechanism. It is possible that these mechanisms occur simultaneously even though their respective relative roles have not been adequately evaluated.
Direct phenotypic benefits
Individual voters receive direct benefits from their partners and this results in an immediate increase in fecundity, or the number of generated offspring. If competitive sex displaying reliable ornamental properties indicates some immediate benefits then strong selection will support mating bias. Having a mating preference is advantageous in this situation as it directly affects reproductive fitness. Direct benefits are widespread and evidence for evolutionary mechanisms is well supported in empirical studies.
One example of sexually selected properties with immediate benefits is the bright feathers of the northern cardinal, a common backyard bird in the eastern United States. The male northern cardinal has a striking red fur while the females are more vague in color. In this example, women are the sex of voters and will use the brightness of male hair as a signal when choosing a partner because men with brighter hair have been shown to feed their child more often than men with dull fur. This increase helps caring for adoptive children of some burden from mothers so that she can raise more offspring than she can without help.
In big reed warblers, women tend to be attracted to men with more repertoire of songs because they tend to be princes with better eligibility. Thus, they get indirect benefits for their own children. In Utetheisa ornatrix , women choose men based on body size, systemic contents of pyrrolizidine alkaloids, and glandular hydroxidaneid content. As a result, these women exhibit direct and indirect phenotypic benefits: they have less vulnerable to predation because of their increased size and higher alkaloid content, improved viability and fitness.
Sensory bias
The sensory bias hypothesis states that preference for nature develops in a non-married context and is then exploited by one sex to gain more opportunities for mating. Competitive sex develops traits that exploit a pre-existing bias that voter sex already has. This mechanism is thought to account for the remarkable differences in traits in closely related species as they result in differences in signal systems leading to reproductive isolation.
Sensory bias has been shown in guppies, freshwater fish from Trinidad and Tobago. In this mating system, female guppies prefer to mate with males with more orange body color. However, outside the context of mating, the two sexes prefer animate orange objects that show that their initial preferences evolved in other contexts, such as foraging. Citrus fruits are rare foods that fall into guppy river dwellings. The ability to locate these fruits quickly is an adaptive quality that has developed beyond the context of mating. Sometime after the affinity for the orange object appears, the male guppy exploits this preference by combining large orange spots to attract females.
Another example of sensory exploitation is in the water mite Neumania papillator , an ambush predator that hunts copepods (small crustaceans) passing in the water column. While hunting, N. papillator adopts a characteristic attitude called 'clean position' - their first four legs are held into a water column, with their four hind feet centered on aquatic vegetation; this allows them to detect the vibrational stimuli generated by the swim prey and use this to aim in the direction and clutch of the prey. During courtship, men are actively seeking women - if a man finds a woman, he slowly revolves around a woman while trembling first and second legs nearby. Male leg motion causes women (who are in 'clean position') to steer toward often holding men. It does not damage a man or hinders the next courtship; the male then saved the spermatophores and started excited the fan and jerk the fourth pair of his legs over the spermatophore, producing a stream of water passing through the spermatophores and toward the woman. Taking sperm packs by women will sometimes follow. Heather Proctor hypothesizes that the thrilling vibration of the male legs is made to mimic the vibrations that a woman detects from the swim prey - this will trigger a female prey response to female orientation and then grip the man, mediate courtship. If this is true and men exploit a female predation response, hungry women should be more receptive to male vibrations - Proctor found that unlicensed females perform orientation and coupling in males significantly more than eating confined females , consistent with the hypothesis of sensory exploitation.
Other examples for the mechanism of sensory bias include properties in auklets, wolf spiders, and manakin. Further experimental work is needed to achieve a more complete understanding of the prevalence and mechanism of sensory bias.
Fisherian escape and hypothesis of sexy men
This hypothesis refers to the combined choice for women to be interested and, also, selection for men to be interesting . This can lead to mutually reinforcing coevolution. If the runaway selection is strong enough, it may incur significant costs such as increased visibility to predators and energetic costs to maintain a full expression of those properties. Therefore the feathers are extravagant of peacocks, or a number of marriage lollels are displayed. This model does not predict genetic benefits; on the contrary, reward more pairs.
In a study conducted on large reed warblems, models based on the polygynous threshold and hypothesis of sexy children predict that women should benefit either short-term or long-term evolution in this mating system. Although the importance of women's choice is indicated, this study does not support the hypothesis. Other studies, such as those done on long-tailed widowbirds, have indicated a female preference. Here, the female selects the stud with a long tail, and even prefers the man with the tail that is experimentally extended over the short tail and whose length occurs naturally. Such a process shows how women's choices can lead to excessive sexual traits through the selection of fishermen.
The indicator character
Character indicators are those that indicate the overall quality of a good individual. The traits that are considered attractive should show a wide genetic quality in order for selection to support them and a preference for evolution. This is an example of the indirect genetic benefits received by the sex of the electorate because marriage with that individual will produce high quality offspring. The hypothesis indicator character is divided into three highly related subtopics: the theory of defects in sexual selection, a good gene hypothesis, and the Hamilton-Zuk hypothesis.
People value the importance of certain characteristics differently when referring to themselves or others who are ideal for long-term partners. Research shows that women consider traits that indicate genetic fitness as more important to their own spouses, and properties that benefit others are proritic for their sister's ideal partner.
The character of the indicator depends on the conditions and has associated costs. Therefore, the individual who can handle this cost well ( cf. "I can do X [here, hang on] with one hand tied behind me") should be wanted by sex selector for genetic quality their superior. This is known as the flawed theory of sexual selection.
A good gene hypothesis states that voter sex will pair up with individuals who have traits that signify genetic quality as a whole. Thus, they benefit evolutionarily for their children through indirect benefits.
The Hamilton-Zuk hypothesis argues that sexual ornamentation is an indicator of parasites and disease resistance. To test this hypothesis, red forest chicken boys are infected with parasitic roundworms and monitored for growth and developmental changes. Women's preferences are also evaluated. What the researchers found was that parasites affect the development and the final appearance of the decorative properties and that females prefer uninfected men. This supports the idea that parasites are an important factor in sexual selection and partner choice.
One of the many examples of indicator traits is patches depending on the condition of the red feather around the face and shoulders of the man's house fin. These patches vary in brightness among individuals because the pigments that produce the red color (carotenoids) are limited in the environment. Thus, men who have a high-quality diet will have a brighter red hair. In the manipulation experiments, the women's house pipes are shown to select men with bright red spots. Also, men with a brighter natural patch are better dads and show a higher offspring rate than boring males. This study is highly cited in the literature and provides strong support for the hypothesis of indicators of indicators related to direct benefits.
Genetic compatibility
Genetic compatibility refers to how well the genes of two parents function together in their offspring. Choosing genetically compatible couples can produce optimal offspring and primarily affect reproductive fitness. However, genetic compatibility models are limited to certain traits due to complex genetic interactions (eg, major histocompatibility complexes in humans and mice). Gender voters should know their own genotypes as well as the genotypes of potential mates to choose the right partner. This makes the component of genetic compatibility testing difficult and controversial.
Controversial but well-known experiments show that human females use body odor as an indicator of genetic compatibility. In this study, men were given a plain shirt to sleep for two nights to give the aroma sample. The college ladies were then asked to assess the odor of some men, some with the MHC (major histocompatibility complex) gene similar to their own genes and others with different genes. MHC gene code for receptors that identify foreign pathogens in the body so that the immune system can respond and destroy them. Because each gene is different in MHC code for different receptor types, it is expected that women will benefit from marriage with men who have different MHC genes. This will ensure better resistance to parasites and diseases in offspring. The researchers found that women tend to assess higher odor if male genes are more unlike their own genes. They concluded that odors are affected by MHC and that they have consequences for the choice of spouse in the current human population.
Similar to humans from stink rating experiments, animals also choose pairs based on genetic compatibility as determined by evaluating the potential for their partner's body odor. Some animals, such as mice, even assess the genetic compatibility of couples based on the smell of their urine.
In a study studying a three-spined stickleback, researchers found that women prefer to mate with men who share a greater diversity of histocompatibility complex (MHC) and otherwise have a special MHC halotype against common parasites Gyrodactylus salaris
The genetic diversity of animals and the success of live reproduction (LRS) at the MHC level is optimal at the middle level rather than the maximum, although MHC is one of the most polymorphic genes. In one study, the researchers found that heterozygous mice in all MHC loci were less resistant than homozygous rats in all loci to salmonella, so it seems unfavorable to display many different MHC alleles due to increased T-cell loss, which helps immune organisms. system and trigger the right response.
MHC diversity may also be correlated with MHC gene expression. As long as the inherited component exists in the expression pattern, natural selection is able to act on that trait. Therefore, gene expression for the MHC gene may contribute to the natural selection process of a particular species and is in fact relevant in evolution. For example, in another study of the three-spined stickleback, exposure to parasite species increased the expression of MHC class IIB by more than 25%, proving that parasitic infections increase gene expression.
MHC diversity in vertebrates can also be generated by recombination of alleles in the MHC gene.
Reversal of sex roles in animals
In species where bias is present, women are usually the voters' sex because they provide larger parental investments than men. However, there are some examples of sex role reversals in which women have to compete with each other to marry opportunities with men. Species exhibiting parental care after birth of the offspring have the potential to overcome gender differences in parental investment (the amount of energy donated per parent per offspring) and lead to a reversal in sex roles. The following is an example of the choice of male partner (sex role reversal) in some taxa.
- Fish: Males usually show a high level of parental care (see pipefish, scissortail sergeant, and sea horse). This is because women will store their eggs in a special musing bag owned by men. She did not participate in parental care after this event. The man then has the burden of raising his own offspring that takes energy and time. Thus, men in this species should choose among women who compete for mating opportunities. Surveys in some pipefish species suggest that gender differences in parental care levels may not be the only reason for the reversal. The marriage system (eg Monogamy and polygamy) may also greatly influence the appearance of the choice of male partner.
- Amphibian: Male poison dart frog ( Dendrobates auratus ) takes on the role of an active parent. Females are lured by males to raise the sites where they store their eggs. Men fertilize these eggs and take on the burden of defending and caring for the young until they are self-sufficient. Because men contribute to higher levels of parental investment, women must compete for opportunities to leave their eggs with limited men available.
- Birds: Bird species are usually biparental in care, and perhaps also mothers like Chicken-of-the-the Guianan. But the reverse may also apply. Male male Jacanas give all the parents care after the eggs have been laid by the females. This means that the males should incubate the eggs and keep the nest for long periods of time. Because men invest more time and energy into their offspring, females are very competitive for the right to lay eggs in established nests.
- Mammals: There are no confirmed cases of the role of sex that reverses mammals, but the female leopard has a distinctive anatomy and behavior that has paid much attention. Female leopard hymen are much more aggressive than men because of their high levels of androgens during development. The increase in male hormones during development contributes to the enlarged pseudopenises involved in marriage and birth. Although the role of anatomy and behavior differs from accepted norms, leopard hyenas are not an inverse sex role because females do not compete with each other for couples.
Speciation
Over the years it has been suggested that sexual isolation caused by differences in mating behavior is a precursor for reproductive isolation (lack of gene flow), and consequently speciation, in nature. Picked partner behavior is considered an important force that can produce speciation events because the power of selection for attractive properties is often very strong. Speciation with this method occurs when preference for some sexual traits shifts and produces a pre-zygotic barrier (preventing conception). These processes are difficult to test to date with advances in genetic modeling. Speciation by sexual selection is increasingly popular in the literature with increasing theoretical and empirical studies.
There is evidence of early speciation through partner preferences in guppies. Guppies are located in several isolated rivers in Trinidad and the geographical patterns of male colors differ. Female guppies have no color but their preference for this color pattern also varies in different locations. In couples choice studies, female guppies are shown to select men with a distinctive color pattern from their original flow. This preference can produce reproductive isolation if two populations touch again. There is a similar trend that is shown in two species of white butterfly, L. reali and L. sinapis. Women sinapis control couples choice by only doing specific marriages, while males try to mate with one of the species. The choice of the female pair has encouraged the speciation of two white woods.
The black bird stall, North American bird, is another example. Asymmetric recognition of local and non-local songs has been found between two black blue warher populations in the United States, one in the northern United States (New Hampshire) and the other in the southern United States (North Carolina). The men in the north of the population strongly respond to local male songs but are relatively weak to non-local male southern songs. In contrast, southern men respond equally well to local and non-local songs. The fact that northern men show differential recognition suggests that northern females tend not to mate with "heterospecific" men from the south; therefore it is not necessary for the northern men to respond strongly to the song of the southern challenger. Barriers to gene flow exist from South to North as a result of female choice, which can eventually lead to speciation.
Pair options in humans
In humans, men and women differ in their strategies to get a partner and focus on a certain quality. The strategies used by each sex differ in terms of whether they are long term or short term. The choice of a human partner depends on various factors, such as genes, negative traits, and parasitic stress.
Choice of female partner
Although, in humans, both men and women are specialized in terms of who they decide to mate with, as seen in nature, women show a selection of even more couples than men. According to the Bateman principle of the Lifespan Reproductive Success (LRS), human women display the fewest variants of the two sexes in their LRS due to the high mandatory investment, the nine-month gestation period, as well as the lactation after birth in order to feed the child so that their brains can grow according to the required size.
Historically, sexual selection of human women can be examined by looking at ways in which men and women are sexually dimorphic, especially in traits that serve other evolutionary purposes. For example, male characteristics such as beard attendance, lower overall sound tone, and higher mean height are considered sexually selected features because they benefit the women who opt for them, or on their offspring. Experimentally, women have reported preference for men with beards and lower voices.
The choice of a female partner depends on many coincidental male characteristics, and the trade off between many of these traits should be assessed. The most prominent key features for the choice of a human partner, however, are parent investments, provision of resources and the provision of good genes for offspring. Many phenotypic features are considered to be chosen because they act as an indication of one of these three main traits. The relative importance of these traits when considering differential selection differs depending on the type of female mating arrangement involved. Women usually use long-term mating strategies when choosing a partner, but they are also involved in short-term mating arrangements, so that their partner's preferred preference changes depending on the function of the type of arrangement.
Short-term mating strategy
Women do not always seek and engage in long-term marriage arrangements. This is evidenced by factors such as the tendency of men who evolved to seek multiple sexual partners - a trait that can not evolve if women are not historically involved in short-term arrangements - and by some women's tendency to pursue matters outside the couple long-term.
David Buss lays out some hypotheses about the choice of women's short-term partner function:
- Resource hypothesis: Women may engage in short-term marriages to obtain resources they may not be able to obtain from long-term partners, or that long-term partners may not be able to provide consistently. These resources can be food, protection for women and children from aggressive men who may arrest or sexually compel them, or status, by providing women with higher social standing. Women can also benefit from having some short-term marriage arrangements through paternity confusion - if paternity of the offspring is uncertain, it may be able to gather resources from some men as a result of this uncertainty.
- Genetic benefit hypothesis: Women may choose to engage in short-term marriage arrangements to aid conception if long-term partners are infertile, to obtain superior genes for long-term partners, or to obtain genes different from their partner's genes and increase genetic diversity of offspring. It deals with what is known as the hypothesis of the sexy child; if a woman acquires a gene from a high-quality male, her offspring is likely to have a higher spouse's worth, thus increasing her reproductive success.
- Co-switch and partner switch: Women may engage in short-term marriage arrangements to cause their long-term partners to terminate their relationship; in other words, to facilitate separation. Women can also use short-term marriages if their current partner has depreciated in value, and they want to 'trade up' and find a partner they believe has a higher value. Short term for long-term goals: Women may use short-term sexual relationships to assess the value of a partner as a long-term partner, or in the hope that short-term arrangements will produce long-term ones.
Long-term mating strategy
In long-term marriage arrangements, women usually look for men who will provide high levels of parental investment, and who can provide resources for women or their offspring. The provision of economic resources, or the potential for a lot of economic resources, is the clearest sign of a man's ability to provide resources, and women in the United States have been shown experimentally to assess the importance of their spouses' higher financial status than men. However, many other traits may act as a signal to a man's ability to provide sexually-chosen resources in the evolutionary history of women. This includes older ages - older men have more time to gain resources - perseverance, dependency and stability - if women's long-term partners are unstable emotionally or unreliably then provision of their resources to him and his descendants tend to be inconsistent.. In addition, the costs associated with emotionally unstable pairs such as jealousy and manipulation may outweigh the benefits associated with the resources they can provide.
The choice of a female partner is not as simple as choosing a partner that displays all the qualities she wants. Often, potential mates will have some desirable qualities and some who do not, so women should assess the relative costs and benefits of their potential partner nature and 'trade off'. The choice of a female partner will also be limited by the context in which they make it, resulting in a choice of conditional pairs. Some conditions that may affect the choice of a female partner include the attraction that women perceive themselves, the personal resources of women, couples imitating and parasitic stress.
Male pairs selection
Generally, it is not uncommon for men in a species to be the sex of voters. There are many reasons for this. In humans, after sexual reproduction, women are required to bear nine months of pregnancy and delivery. This means that women naturally provide greater parent investments for offspring, rather than men. Male males have larger numbers of gametes than women, which are recharged at a rate of about 12 million per hour. In contrast, a female human is born with a fixed number of eggs that are not replenished during lifetime. This gives men a greater chance to mate and reproduce than women, hence why women are usually more picky.
Although not the usual sex of voters, human males may be affected by certain female characteristics when making decisions about a potential partner:
Short-term mating strategy
When finding short-term partners, men greatly value women with sexual experiences and physical attractiveness. Men looking for short-term sexual relations tend to avoid women who are interested in commitments or require investment.
Examples of short-term mating strategies in men:
- Many sexual partners: When looking for short-term sexual relationships, men may expect there to be as little time as possible between each pair. When having sex with multiple partners, it is important to recognize that the risk of contracting a sexually transmitted disease may increase if contraception is not used.
- Physical attractiveness: Men who are attracted to short-term sexual intercourse are more likely to prioritize information about potential partner's body, rather than their face. When finding women for short-term relationships, compared to long-term relationships, men tend not to prioritize factors such as commitment.
- Standard relaxation: It has been reported that men are more likely to engage in sexual intercourse with women of lower intelligence, independence, honesty, generosity, athleticism, responsibility, and cooperation when this relationship is short-term. Men may be more accepting of lower standards, than they usually like, because they do not enter into long-term relationships with this person.
- Sexual experience: Many men assume that women who have been involved in previous sexual experiences tend to have a higher sex drive than women who do not. These women are also more accessible and require less courtship.
Long-term mating strategy
Although from an evolutionary perspective women are usually the sex of the electorate, if a human male has a desire to reproduce, he may seek a certain quality in a potential mate who can be the mother of his descendants. Humans have the ability to rely on biological signals of reproductive success and non-biological signals, such as a woman's desire to marry. Unlike many animals, humans can not consciously display physical changes to their bodies when they are ready to mate, so they must rely on other forms of communication before engaging in consensual relationships.
Men may be looking for:
- Commitment and marriage: A human man may be interested in marrying a woman looking for marriage. This is because it has exclusive sexual access to women, so any offspring produced in that relationship will be genetically related to it (unless the woman has sex with another man outside the marriage). This increases the likelihood of paternity certainty. With two married parents investing in their offspring, their chances for survival can increase; therefore the male DNA will be passed on to the offspring children. Also, a man who is interested in committing to a woman may be more attractive to a potential partner. Men who can promise future parental resources and investments will likely be more attractive to women than men who do not want to commit to them.
- Facial symmetry: The symmetrical face has been assessed as a good general health signal and a woman's ability to withstand adverse environmental factors, such as pain.
- Femininity: The feminine face can be a signal of youth, which in turn signals a strong reproduction value. When a woman gets older, her facial features become less feminine due to aging. Femininity can also be associated with resistance to disease and high estrogen levels, which is a factor that indicates a reproductive value for a potential partner.
- Physical beauty: The observable characteristics of a woman can indicate good health and ability to reproduce, qualities that may be desired by men. This may include smooth skin, absence of lesions, muscle tone, long hair and high energy levels.
- Source: Men looking for long-term partners may seek to achieve high status or resources, such as their own homes or job promotions. This can increase their chances of attracting the desired partner.
- Waist-to-hip ratio: The waist-to-hip ratio of 0.7 is an indicator of fertility, lower long-term health risks and indicates that the woman is not pregnant. Men tend to want these qualities in couples, as they increase the chance of survival of any shared offspring.
- Youth: Both young and old men are attracted to women in their twenties. Younger-looking faces are usually considered more attractive by men. This can include faces that do not have many wrinkles or where there is a very clear skin. A younger-looking female tends to attract couples, because it shows that it has a higher reproductive value than the older, alternative, female. When a woman passes her twentieth birthday, her reproductive value continues to decline until around age fifty.
Parasites-stress on the choice of a human partner
The theory of parasitic stress, otherwise known as pathogenic stress, is where parasites or diseases emphasize the development of organisms, which lead to changes in the preferences and choice of their spouses. In communities with high prevalence of parasites or pathogens, greater emphasis is placed by members of the community, on the physical attractiveness/good appearance of their spouses or potential partners, compared to members of the community with a parasitic or lower disease prevalence that puts less emphasizing physical attractiveness. This shows that physical attractiveness is the way in which humans can determine resistance to parasites, because it is believed that parasites and illness will worsen the appearance of people who suffer or suffer from illness, and will also limit the amount of high quality. couples who are resistant to pathogens.
Hamilton-Zuk Hypothesis
The Hamilton-Zuk hypothesis (see Indicator features) strongly influences research on the choice of a human partner. It has been found that men of all cultures have been found to assess women's attractiveness is very high, but when the risk of parasitic infection is high, men assess the attractiveness of women much higher. In cultures where parasitic infections are very high, community members use every cue available to them to determine the physical health status of potential partners. Regardless of wealth or ideology, areas of society that are at higher risk or have higher levels of parasites and diseases, women will assess higher masculinity.
- Scarification: In pre-industrial body markers, such as tattoos or scarifications, it has been suggested as a way to attract potential mates for one's reproductive quality. However, Singh and Bronstad (1997) found that when there was an increase in the prevalence of pathogens only predicted female stomach scarification and no other anatomical areas, without evidence for male scarification.
- Masculinity: In societies where there is a high level of parasites or illness, the women of that society, as the overall health of their members declines, begins to put more emphasis on masculinity in their partner's preferences. In particular, women look for signs of increased masculinity in areas such as male voice, face, and shape. The face, in particular, can hold some cues for parasitic resistance and has been the most interesting research subject.
- Polygamy: The tropics were initially associated with polygynous communities and this is the result of the ecologically richer and homogeneous environment. However, while the tropics are associated with polygamy, pathogenic stress, considered a better polygamy indicator and positively correlated with it. Furthermore, during human evolution, areas with high levels of parasitic stress may have altered the polygamy threshold and increased the number of certain types of polygamy present in society.
Criticism
Gangested and Buss (2009) say that while research suggests that parasitic stress may affect only the choice of spouses, females look for "good genes" that exhibit parasitic resistance, in areas with high parasite prevalence. John Cartwright also pointed out that women may simply avoid parasitic transmission to themselves rather than be they picking men with good genes and that women are looking for more than just a resistant parasite gene.
Major Histocompatibility Complex (MHC) or in humans, Human Leukocyte Antigen (HLA), produces protein products that are essential for the functioning of the immune system. The MHC genes have very high variability, assumed as the result of selection and choice of pairs that depend on parasites that depend on frequency. It is believed that promoting heterozygosity increases the likelihood of survival for offspring and avoiding inbreeding.
Smell preferences
In experiments using mice, a selection of MHC-related pairs indicates that the odor cues play a role. In humans, it has generally been shown that male and female correlations will assess the smell of the opposite sex as more pleasing, if humans have different MHC-antigen to them. However, women using contraceptive pills rated the same MHC odor-men as more pleasurable, it is not known why women on the contraceptive pill levels of contraceptives in this way. It was found that when processing MHC-a similar odor is processed more quickly.
Face preferences
Human face preference has been shown to correlate with MHC-similarity and MHC-heterozigosity. Research on MHC-similarity relates to limited facial attractiveness but research so far suggests that women when thinking about long-term relationships will choose men who have similar MHCs. While facial asymmetry has not been correlated with MHC-heterozygosity, it appears that healthy skin appears. It appears that only MHC-heterozygosity and no other genetic markers are correlated with male facial attractiveness and it has been shown that so far no correlation has been found in women.
See also
- Expanded female sexuality
- Filter theory (sociology)
- Male male sexuality
- Koinophilia
- Mate takes care of man
- Parent's investment
- Psychological adaptation
- Flirt
- Sexual conflict
- Sexual selection
- The evolution of human sexuality
References
External links
- Summary
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