1. One of the most robust find

Reproduction occurs by passing on genes which are the”blueprint” for inherited traits. If an organism “survives” withoutpassing on traits, its survival “doesn’t count” in evolution.

Every individual has only so much energy. Some energy is spentstaying alive — that is, finding food and not being somebody else’sfood — and what’s left over can be spent on reproduction. In otherwords, there are limits to reproduction. Of course, the variousslices of that reproductive energy pie also vary between males andfemale of all species.

(a) The female reproductive pie is much more complex. There arecosts to pregnancy, lactation for mammals, and then whatever elseis needed to bring a kid up to sexual maturity so they can pass ongenes as well. But there are all sorts of ways, from anevolutionary point of view, for females of a species to distributethat energy and bring up babies successfully. She might have asmany babies as she can in one shot, litters that is, and have themas often as possible. For that kind of female, reproduction is anassembly line of cheap production per kid. Or a female might optfor the other end of the scale and make one baby at a time and waitfor a very long time to see if that one investment pays off.Obviously, humans are on slow side of the baby productioncontinuum. Evolution has selected for this path because there arefeatures of our species that require great investment by mothers.Human infants might have big brains compared to other mammals, butthey need to get even bigger once outside the womb. And so humaninfants are actually born neurologically unfinished. They can’tcling, sit up, feed themselves, or run from predators. And so thevery nature of what it takes to be an adult human puts constraintson how many children a mother can have at a time.

Women can reproduce for about half of their lifetime and canonly give birth about once every year or so. So it makes sense thatwomen can only have a fraction as many children as men . One studyestimated a woman can have around 15 pregnancies in a lifetime anddepending on how many babies she births for each pregnansy, she’dprobably have around 15-30 children.

(b) The various slices of that reproductive energy pie also varybetween males and female of all species. Males don’t gestate orlactate so they pass on the most genes by flitting from female tofemale making as many babies as they can, and then walkingaway.

(c) In humans, when choosing a mate of the opposite sex, femalesplace high preference for a mate that is physically attractive.Thisties in with the idea that women discriminate between men onhypothesized fitness cues. The more physically attractive a man is,the higher his fitness, and the better his genes will be. Women areattracted to more masculine traits (e.g. strong jawline, a moremuscular body). Indeed, men who are more masculine tend to have ahigher number of sexual partners.

Women seem to judge potential mates by how masculine theirfeatures are, new research shows. Men with square jaws andwell-defined brow ridges are seen as good short-term partners,while those with more feminine traits such as a rounder face andfuller lips are perceived as better long-term mates.Male physicalattractiveness: Immunocompetence Handicap Hypothesis,Waist-to-chestratio, Fluctuating Asymmetry,Resources,Age.

(d) It is a well-known fact that men assign as far greatersalience to the attractiveness of a potential mate when consideringtheir mating preference than women do.

Body shape and size: The first factor that has been shown toimpact mating preference in males is that of Waist Hip Ratio (WHR),that is the relationship between waist circumference and hipcircumference, as it has been suggested as a marker of age,reproductive status and health. It was also found that women with aWHR of 0.7 were rated the most attractive, youthful, fertile andhealthy, when compared to other WHR’s. Furthermore, the currentresearch also found that those women with a WHR of 0.7 and ofnormal weight were rated the most attractive, and whereas thosewith a WHR of 0.7 but whom were underweight were rated as moreyouthful but not as attractive. An extension of WHR research showedthat there is an impact of breast and hip size upon attractiveness;Women with large breasts, and small hips were rated more attractivethan women with small breasts and small hips, as well as findingthat women with large hips were rated less attractive irrespectiveof breast size.

Skin condition: Skin condition has been found to be an honestindicator of sex hormones which may indicate levels of fertility.The study directly examines the relationship between an individualhaving acne and the levels of hormones that could potentiallyindicate low fertility, therefore guiding attractiveness for matepreference. This skin condition, attractiveness link has beencorroborated by research that found that skin colour, skinhomogeneity and facial adiposity (how fat is deposited around theface) all predict female attractiveness and therefore, matepreference. Skin tone has also been found to be an honest indicatorof youthfulness and fertility; as well as research showing thefirst links between estradiol and female facial redness, in whichas a woman reaches the peak of her ovulatory cycle her facialredness increases. This research would suggest that male matepreference would be guided by the individuals skin tone, lookingfor women with redder facial skin tones they indicate peakfertility and optimal opportunity for reproductive success.

Neoteny: Males show a preference for neotenous or youthfullooking features in women, such as; big eyes, a small nose, andfull lips.These features act as a signal of fertility as they arecaused by high estrogen and low testosterone. As a result ofevolution these features are deemed as highly attractive as theywould indicate a higher chance of successful reproduction. Thismale mate preference for neoteny has been shown in research inwhich men were asked to morph images of female faces until an idealface was achieved.

Chastity: Chastity is deemed highly desirable across cultureshowever the extent of its importance shows some variation. Theimportance of chastity to males, in an evolutionary sense has beenlinked to paternal certainty; as before contraception, the only wayto ensure a woman had not been inseminated by another man was ifshe were chaste.

(e)Females have limitations such as gestation time (typically 9months), then followed by lactation which suppresses ovulation andher chances of becoming pregnant again quickly.In addition, afemales ultimate reproductive success is limited due to ability todistribute her time and energy towards reproducing.The metabolictask of converting energy from the environment into viableoffspring falls to the female, and the rate at which she canproduce offspring is limited by the rate at which she can directmetabolic energy to the task The reasoning for the transfer ofenergy from one category to another takes away from each individualcategory overall. For example, if a female has not reached menarcheyet, she will only need to be focusing her energy into growth andmaintenance because she cannot yet place energy towardsreproducing. However, once a female is ready to begin putting forthenergy into reproduction she will then have less energy to puttowards overall growth and maintenance.Females have a constraint onthe amount of energy they will need to put forth into reproduction.Since females go through gestation they have a set obligation forenergy output into reproduction.

(f) Males, however, do no have this constraint and thereforecould potentially put forth more offspring as their commitment ofenergy into reproduction is less than a females. All thingsconsidered, men and women are constrained for different reasons andthe number of offspring they can produce. Males contrastingly arenot constrained by the time and energy of gestation or lactation.Females are reliant on the genetic quality of their mate as well.This refers to sperm quality of the male and the compatibility ofthe sperms antigens with the females immune system.If the Humans ingeneral, consider phenotypic traits that present their health andbody symmetry. The pattern of constraints on female reproduction isconsistent with human life-history and across all populations.

A difficulty in studying human reproductive success is its highvariability. Every person, male or female, is different, especiallywhen it comes to reproductive success and also fertility.Reproductive success is determined not only by behavior (choices),but also physiological variables that cannot be controlled.

(g)People tend to perceive that women are more risk averse thanmen. Stronger, taller, and more attractive people are perceived tobe more risk tolerant.Women are perceived to be more risk averse.That means that women are at a disadvantage when it comes togetting support for risk-taking.