Trivers (1972) defined parental investment as any investment that a parent makes in one offspring leading to an increased likelihood of that offspring surviving to the productive age and thus enhance the parent’s reproductive success, at the expense of the parent’s ability to make investments in another offspring. Parental investment theory (PIT) views each offspring as an investment that is independent of the other offspring. Therefore, an increase in investment in one offspring may be associated with a decrease in parental investment in the other offspring. Parental investment may be in the form of metabolic investment, feeding, guarding the young, and any other investment intended to benefit the young offspring. This definition suggests that parental investment involves resources such as time and energy that parents commit to the upbringing of their offspring to enable them to reach reproductive ages, at the expense of investments in another offspring. According to Trivers (1972), the sex that invests the most in the offspring undergoes evolution to become more selective in choosing a mating partner. The sex that invests less evolves to have a more competitive temperament and to become more opportunistic in choosing mating partners (Trivers, 1972). PIT may be used to explain male and female psychology to a considerable degree.
PIT might be used to understand reproductive success and behavior for couples. In some countries where parents are not limited by law on the number of children they should have, some couples will have fewer children than others, which results in compromised reproductive success. Trivers (1972) argued that a large parental investment on one offspring impairs the parent’s ability to have more children. The decrease in productive success as a result of investment in an offspring consumes the scarce resources such that parents have no more to invest in another offspring (Trivers, 1972). PIT suggests that men are more likely to invest in children who are more likely to enhance their father’s long-term well-being and inclusive fitness (Fox & Bruce, 2001).
PIT may be used to understand why men compete for women. According to PIT, the sex that makes greater typical parental investment per offspring than the opposite sex becomes the limiting resource for that sex (Trivers, 1972). Therefore, members of the sex that invest less engage in a competition among themselves to get an opportunity to have offspring with a member of the sex that invests more. The reason is that the reproductive success of the sex investing less in the offspring depends on the success with which they can invest in the offspring of several individuals from the sex that has become the limiting resource (Trivers, 1972).
Success in intrasexual competition may depend on characteristics such as greater strength, big size, agility, good confidence, and being cunning. These traits might evolve because individuals with them have higher chances of being reproductively successful than their same-sex competitors. The female sex invests more in the offspring. Therefore, these observations might explain why men would compete with their fellow men, in an effort to gain access to women. Usually, this is a competitive interaction among members of the male sex. The reason is that males make fewer investments in their offspring than females (Trivers, 1972). Males tend to be more involved than women in the production of art, music, and literature (Miller, 1998). Males also compete with each other through the acquisition of resources in order to win women. This resource acquisition competition has evolved to become, ambitiousness, willingness, and display of resources (Gould & Gould, 1989). The argument might also be extended to include an explanation for why people received different recognitions for their accomplishments (Gould & Gould, 1989).
Male competition for females might be used to explain male’s aggressive behavior. Men are responsible for most of the violent deaths than their female counterparts. Moreover, men tend to be more advantageous in relation to reproductive success when they are able to access power, advance social status, and acquire great amounts of resources. This is known to happen in the case of women. Men strive to achieve these because it will give them an advantage when it comes to winning females. Women tend to prefer high status, powerful men, and the ones with resources because those are able to provide for their offspring.
PIT may explain why women who want short-term mating partners prefer men that are able and ready to commit immediate resources (Buss, 1994). Unlike men, women do not consider the issue of how many mating partners they have. Multiple short-term mating has no direct effect on the reproductive success of women. The reason is that regardless of how many men a woman can manage to mate with in one year, the result is only one offspring, which could as well be achieved by mating with one man. This is different from the situation observed among men, where the number of mating partners determines their mating success. This way, a woman’s choice of mate is more imperative for women than for men (Kendrick, Trost, & Sheets, 1996). Buss and Malamouth (1996) observed that women make more investments in the offspring than males. The female investment is in the form of gestation and child care. This way, men tend to compete for women, in order to access them and make them their mating partners. Men who are able and willing to commit respected resources, which might have given rise to human male characteristics such as assertiveness, aggressiveness, and sensitivity to hierarchy observed among human males (Buss, 1996).
Therefore, women tend to acquire more resources so as to increase their reproductive success. Men vary in their abilities and willingness to invest in the offspring. Therefore, women have a selective advantage in choosing men who are able and willing to invest resources. Women who are able to make these choices can afford to offer protection to their children, and provide them with food, which enhances their chances of surviving and reaching reproductive ages. Therefore, women value those indicators that suggest men will immediately commit resources to them. In his study, Buss (1994) found that in search for short-term mates, women valued men who spend a lot of money early; men who give gifts early on and men who seem to have extravagant life styles. These observations suggest that women might not be interested in men who might appear to them as reluctant to expend resources on them immediately, especially those display such traits early on (Buss, 1994).
There are differences in male and female behaviors in the choice of short-term mating partners. PIT may explain why women interested in choosing a long-term mating partner tend to choose men who are able to provide commit resources to their children. They determine the man’s willingness to provide for their offspring by assessing the man’s ambitions, earning capacity, professional degrees and wealth. According to PIT, investments in the offspring enhance the chances of their offspring’s survival to the reproductive age. Buss (1994) found that women interested in a long-term relationships desired men who were likely to be successful in their profession; who had a higher likelihood of earning a lot of money; and who had a reliable future in their careers.
These traits were more important to women than they were for men. It has been observed that women may reject men who are unable or are willing to invest in their offspring. Buss (1994) also reported that in 36 of the 37 cultures they investigated, women greatly valued financial prospects than men in seeking for a long-term mate. Women particularly indicated they greatly valued social status and ambition-industriousness among men they would consider for a long-term relationship. In another study, Buss (1989) identified supply possibility as a key factor for women interested in mates. In particular, women indicated that they would engage in a relationship with a man who was determined, had good financial prospects, was determined, productive, and mature in terms of age and emotions (Buss, 1989). These observations are consistent with those of Betzig (1989). In his ethnographic study of 160 societies on the causes of divorce, Betzig (1989) found that many marriage dissolutions were as a result of the man’s failure to provide financial support to the wife and children. Twenty-one societies reported inadequate economic support as a cause of divorce. Women seemed to divorce men who were not able to provide enough food, adequate housing, and adequate clothing. Women were also found to divorce men who were unable to provide material means.
Unlike women, men interested in short-term mate tend to minimize commitment and investment, unlike women. Men seem to be repelled by women who tend to be interested in long-term commitments. Buss (1994) found that commitment was not desirable among men interested in the short-term relationship. The reason might be that men are not willing to invest, even when they are able. However, women are interested in commitments. Moreover, men interested in short-term mating partners tend to prefer fertile women. Fertile women are those that are able to have a child now. For instance, a 14-year old is not as productive as a 24-year old woman (Buss, 1994). However, the former is more productive than the latter (Buss, 1994).
Men differ from women in the kind of long-term mates they are interested in. Whereas women seek for a man able and willing to invest resources in the offspring, men looking for long-term mating partners are interested in reproductively valuable women (Buss, 1994). Since reproduction means the degree to which a certain age for women may contribute to the ancestry of the future generations, young women seem to be more valuable to men than older women. For example, a 14-year-old girl is more productive than a 24-year-old woman (Buss, 1994). This might explain why men tend to be attracted to youthful women and physically attractive women (Tesser & Martin, 1996). Since it is not easy to determine the reproductive value of a woman by just looking at her, men rely on physical cues associated with age to assess the reproductive value of a woman. The physical cues that men look at including changes in the skin, lips, ears, patterns of facial features, and muscle tone (Buss, 1994). Cunningham (1986) found that women with large eyes and small nose were perceived as attractive, fertile, and healthy. Buss (1994) found that men were interested in physical attractiveness when seeking short-term mating partners but this consideration was not important for long-term mating partners (Buss, 1994). This observation was made among 37 cultures worldwide. Buss (1994) found that men throughout the world valued physical attractiveness and good looks as key in choosing a mate. The observations might explain why women apply makeup to their faces and wear clothing complimenting their figures, with others choosing to have surgery in order to look physically attractive and youthful. Looking youthful and attractive are associated with higher likelihood of winning a good male who can commit resources to the offspring.
It is important to note that what is considered as beauty may differ across cultures. In particular, cultures might differ in the manner in which they view plumpness and slimness in relation to attractiveness (Buss, 1994). Buss (1994) argued that in cultures with the scarcity of food, being plump is considered as attractive while in cultures of abundance, being slim is the ultimate beauty (Buss, 1994). However, the cues of age and health seem to be the same across cultures (Buss, 1994). Being youthful and attractive for men is not a something that women are interested in. This is because the reproductive capacity of a man is not connected to his age and accurate assessment cannot be realized through appearance (Buss, 1994).
Although the above discussion demonstrates that men and women might be totally different in their choices of mates, there are instances in which both men and women tend to consider similar qualities when looking for a mate. Kenrick and Simpson (1997) found that both men and women were interested in mating partners who were kind, understanding, and intelligent. In addition, PIT suggests that intrasexual competitions, though said be for males, occur among females (Buss, 1994). Another challenge to PIT is that young males are not always interested in young women. Kenrick and Simpson (1997) reported observation in which teenage males tend to be attracted to elderly women.
Another challenge for the theory is that couples perceived as high status and known to have high material wealth might have fewer children than relatively poor couples. This suggests that there must be another explanation for the number of children a couple can have. The explanation provided by PIT that huge investment in one child makes it difficult to invest in other children, and therefore, resolve to have a few children. Eagly (1997) rejected the gender mate selection offered by PIT, arguing that culture provides an explanation for human mate selection criteria. In almost all cultures, males tend to dominate in the society, and therefore, dominate mate selection. Eagly (1997) believed that favored attributes could be applied to women if women where the dominant sex in the society. Given that no known human society where females dominate, Eagle's arguments could not be tested.
The fact that there is no known human society where females dominate does not mean that Eagly (1997) was wrong in her argument. There are several indicators that might challenge the ability of PIT to explain psychological differences in men and women in regard mate choice. The argument she made has been observed in other animal species. For example, among seahorses, intrasexual competition occurs among females who want to win the attention of the males. The female gender has brightly colored ornamentation, as opposed to the dull males. In addition, seahorses challenge the PIT assumption that females invest more than males in the upbringing of their offspring. It has been observed males have a pouch for holding infant seahorses until they mature. This is not consistent with PIT, where females are believed to invest more in the upbringing of their offspring. Moreover, male birds tend to invest more time in the egg-hatching process. Despite these limitations of theory, evidence from apes suggests that the theory could be true (Diamond, 1992). For instance, similar to what humans do, McGrew (1981) reported male chimpanzees went for hunting, guarded their borders, and threw more foliage and rocks (McGrew, 1981). The female chimpanzees were found to spend huge amounts of time to interact with their young ones.
In conclusion, this paper has shown that parental investment theory may be used to understand certain male and female behaviors, especially in relation to mate choice. The theory may be used to understand why couples may have few children and male and female behaviors in the choice of mates. Men tend to differ with women in regard to the factors considers in choosing short-term and long-term mating partner. Much human behavior and culture theories are inadequate in explaining the reasons why men and women tend to behavior differently in relation to mating choice. The analysis in the paper has identified certain instances, in the theory seems unable to account for. Although the theory has been challenged, it is still relevant to understanding male and female behaviors in mate choice.
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