Introduction
Physical beauty in a woman may not be everything, but for good or bad it's certainly very important.  Would Prince Charming have asked Cinderella for a dance and fallen in love with her if she had not been the most beautiful girl at the ball?  The honest answer is probably "No". 

Psychological studies show that men still rank physical beauty the highest among a long list of attributes that they seek in women.  The phrase "I love you for your beauty" is hardly likely to be heard from the lips of a man in these politically correct days, but it is nevertheless often true, at least in the earliest stages of a relationship.  A wonderful mind and personality is great, but sometimes - like Cinderella - you also need to be beautifull create the initial opening. 

A modern model, Valentina,  dressed as a goddess.

The immense amount of time and money that the average women spends on maintaining or improving her physical appearance has been given many justifications, but "I just like to look my best" is very close to "I just like to look beautiful".

It can be reasonably claimed that the continuing lust for physical beauty is more appropriate to the Stone Age than to the modern Internet Age.  The qualities that men find alluring in a woman may be powerful emblems of her health, fertility and resistance to disease, but they say nothing about her moral and intulectual worth.  However, whilst the valuing of physical beauty may cause emotional pain and considerable injustice, it does not prevent its continued worship - as a brief perusal of any magazine stand will prove. 

The increasing number of lawsuits involving claimed discrimination on the basis of looks have made little impact to our attitude, nor have the best efforts of some feminist pressure groups to stop the supposed exploitation of women's body's (e.g. beauty contests) - indeed it can be argued that advances in cosmetics, plastic surgery and a constant media bombardment have increased the pressure on women to be "beautiful".

Poppea Sabina (AD30-65) was considered by ancient authors to be an exceptionally beautiful woman. However to the modern eye, this bust (from Palazzo Massimo alle Terme) shows an unexceptional woman with a large nose, a prominent chin and small lips.  Cosmetic surgery and photo manipulation have raised the bar for what constitutes a beautiful woman.

For hundreds of years, having a daughter selected to join a Sultan's or Raja's harem was like winning the lottery for both the young women and her family.  If she became a favourite then she would wield huge power.

The Competition to be Beautiful
We might be in the 21st century but the brutal reality is that deep down most women know that their appearance and attractiveness to men (i.e. their beauty) matters ...  and sometimes matters a lot. 

Historically (i.e. since the evolution of Homo Sapiens) there has almost always been more adult women than adult men - the dangers of hunting, warfare, travel, feuds, etc. killing many men in their prime.  For a woman, finding a man who was able and willing to look after her was desperately important matter.  Being more beautiful than your peers often meant the difference between a long and even luxurious life - and destitution, starvation and an early death.  When a girl reached puberty in her early teens, the race to find a suitable husband became furiously competitive even if he was many years older. In the middle ages, by 20 she was no longer be considered to be young or a serious contender for an eligible beau, and faced a bleak future.   

Historically, young women often sought and had to accept much older husbands who could support them.  Two paintings by Lucas Cranach the Elder dated 1522 and 1502/3.

The Cinderella story shows to all the girls who read it every night that beautiful women are far more likely to marry "better", richer and socially higher husbands than the ugly sisters.  It is certainly no coincidence that so many of the wives and mistresses of noblemen and royalty that we see in portraits dating back 200 years, 400 years, 600 years, .. and more,  are often considered  exceptionally  beautiful women by their contemporaries - even discounting some generous artistic licence.  And they are almost always many years younger than their husband.

Even today, being beautiful definitely has practical advantages - for example one survey suggests that pretty, tall and slim women earn about 15% more than their more dowdy, shorter and fatter counterparts.  It is perhaps not surprising that women discuss the appearance and beauty of [other] women at least as much as men do, and far more brutally and critically.

For many women, a concern about their looks is not just an important part of being female, but a fundamental of being themselves.  Most mothers enjoy and take great pride in dressing up their daughters from the earliest age with make-up, hair accessories, jewellery and dresses.  A young girl can expect to get more compliments on her appearance than anything else, and soon learns the rewards of looking pretty and being considered beautiful - all of which is reinforced by Cinderella type stories.

A girl's informal beauty lessons and training start by nursery age - and by her teens she will already have spent hundreds, if not thousands, of hours practicing and experimenting.  During puberty, peer pressure often makes her appearance and looks become almost an obsession.  Dissatisfaction is all too common - e.g. about half of all High School girls are on some form of weight control regime, and plastic surgery is increasingly sought!

It's relevant to this site to point out that a transsexual male-to-female woman who transitions as an adult lacks this lengthy childhood beautification "training".  She thus faces an enormous challenge in developing as quickly as possible her female orientation, appearance and presentation - something which other women have been doing since their birth.  This is a great disadvantage, and makes successful "passing" as a woman far more difficult, particularly in the first months after full-time transition.

In the early 20th century Charles Gibson's illustrations of idealised women became so popular that in 1902 he held a competition to find a real-life woman that matched these.  The winner was 17 year-old Belgium-born Camille Clifford.  A brutal corset gave the 5ft 3in tall woman a 38-18-36 figure.

(Above Left) An interesting graphic from 1930 favourably comparing the physique of a popular 20 year-old actress (Anita Page) against an ideal woman derived from the best parts of other leading actresses of the day.  These days, a model agency would immediately reject her as being far too short (64 inches) and too rounded (aka fat at 118 lbs).

(Above Middle) Gisele Bundchen - the top female model of the first decade of the 2000's - weighs only a little more at about 125lbs but is 5 inches taller than Anita at 69 inches. 

(Above Right) Moving in to the 2010's, Andreja Pejic (a transwoman) is another 4 inches taller at 73 inches, and slightly heavy for a super model at 150lbs. 

An analysis of the top 100 female models in 2016 gives an average height of 71 inches (180 cm) and an unhealthily low weight of just 120 lbs (55kg).

The promotional agency TSM published in 2017 a report stating that the average height of its 30,000 female models (95% under age 32) was 67 inches and that their average weight was 114lbs.  It also states that over the last 20 years the average breast cup size of its female models had increased from B to DD! 

What is Female Beauty?
The experts tell us that the physical features and characteristics considered to be "beautiful" are in fact subconscious indicators of fertility and good health, while some other features and characteristics are considered to be "unattractive" because they render a person less fertile or more susceptible to disease and parasite assaults.  For example, a woman with an oestrogen induced small chin and wide waist-to-hip ratio appears to be beautiful because these are physical features that indicate good fertility, childbearing ability and general health.  Of course, many men can have reciprocal testosterone induced features such as rugged chin and a minimal waist-to-hip ratio that indicates their ability to sire healthy children. 

Judging beauty involves looking at another person and subconsciously figuring out whether you want your children to carry that person's genes.   We judge each other by rules that we're often not even aware of.  A man may admire a woman's shapely legs but is also viscerally attuned (for good and bad) to small variations in the size and symmetry of her facial bones, and the placement of weight and fat on the rest of her body. 

It is important to realise that women pragmatically use a different set of criteria when selecting a man to father her children, and the man will support her and her children.  The men are often not the same, as DNA tests are increasingly proving both for both modern and historical liaisons (the accepted family trees of some royal families has become very problematic). 

Research correlates the physical attraction of human males to a set of basic physical features in human females, regardless of culture.  These include:

• signs of youthfulness (vigour, flexibility, bounciness, smooth skin)

• signs of health (clear skin, lack of disease, physical fitness)

• a good figure with an optimal hip-waist ratio and generous bust

• facial and body symmetry

• an infant like face.

To a man, a beautiful woman is more than just a beautiful face - it's the total package!

Our ancestors preferred to mate with "beautiful" individuals in order to leave more, and healthier, offspring than the average individual in the population.  The process of evolution then further emphasises "beautiful" characteristics, for example in women the overhead of an extra pound of fat on the buttocks has self-evidently proven to be a far more successful survival technique than a extra pound of muscle.

The body of a woman cannot evolve quickly enough to reflect short-term changes in what constitutes "beautiful", but does over generations.  Left is a famous painting dated 1489, right is an advert dated 2018.

The possession of beautiful characteristics by a woman acts as a 'certification of biological quality', offering her a significant mating advantage over other women in the competition for partners and reproduction - historically and today.  All men are innately attracted to a beautiful woman, and she is thus more likely to be able to attract and select a high quality, high status, man as her mate - but women can often be pragmatic and he may not be the most beautiful (aka most handsome and physically attractive) partner available.  Women also have an inherent ruthless streak that urges them to seek out the most beautiful mate to sire her children, and separately (and if necessary deceitfully) a high value partner who will best look after her and her children.  Modern DNA testing has revealed that about one in eight children are calling the wrong man "Daddy"!  In many instances a woman's children are sired by someone other than their husband, presumably he is more "beautiful" and sexier than their husband, even if the later offers a more secure life.

Whilst sexual equality may be vogue, the medical evidence is that the two predominant genetic (XX and XY) sexes are drifting ever further apart in their physical appearance.  Women are evolving to appear ever more beautiful and youthful - and evolving far more rapidly than men. 

Men are not evolving towards the model of masculine beauty at the same rate as women because an ugly but rich and high-status man can be successful in attracting a good quality female mate.  A statistical analysis of "beautiful" Hollywood couples shows that their first child is 67% more likely to be a girl than a boy - nature somehow seizing the chance to maximise the birth of child of the sex for whom beauty is the more important.

It's quite possible that in another hundred generations of evolution, the average 35 year-old woman will have the looks and figure of a top 20 year-old model today - and without the surgery.  But by then the standard for beauty will have changed so much that Marilyn Monroe would be considered short, fat and ugly. 

Professional fashion photographers such as Constantino Quero Simons have become fascinated by the appearance of young transwomen, who are often more "beautiful" than cis-women in photo shoots.

 

Above and left, 18-year-old Evie Macdonald, actress and model ticks all the "beautiful woman" boxes.

Youthfulness and Health
Despite the current war against ageism, people's perception of whether a woman is beautiful is still (and will surely remain) closely linked to her age.  While no age is given for the beautiful Cinderella, there are strong indications in the story that she has not long ceased to be a girl in the biological sense, and is certainly still a teenager.

A common finding in studies is that males prefer females who are young, strong and healthy - but above all who are fertile and at the peak of their reproductive potential.  A woman's ability to bear children is dependent upon her age and hormone levels.  A woman is at her reproductive peak around the age of 20, this starts to decline dramatically in the late 20's and will halve by age 35.  Even with the support of modern medicine (HRT, IVF, ...), a pregnancy over age 45 is exceptional.

In one cross-cultural survey, men in all 37 of the societies examined preferred younger wives, on average around 2½ years younger than the male.  And as males get older, they prefer mates who are increasingly younger.  There is actually a natural selection war going on here - the male eye and mind has become astonishingly good at subconsciously picking up the first signs of aging in a young woman - whilst the woman attempts to avoid giving out these signs.

An approximation from multiple sources of a womans perceived attractiveneness (a close
but not exact collorary to beauty) and medical fertilitary at various ages. 1 = maximum.

If a woman is ever going to be considered "beautiful" it's in the years from her late puberty (typically 15 or 16), when her body has rounded out, to her mid 20's, before gravity and the passage of time have started to work their first ravages.  The youthful woman has large eyes and plump lips.  The apparent size of these features' peaks in the early 20's when fertility also peaks.  This facial 'baby fat' melts away as collagen slowly diminishes during a woman's 20's, and the volume in the face also decreases - but a slimmer face with more prominent cheekbones can actually improve the beauty of some women in their mid/late-20's, at least from a modelling perspective.

The male face evolves and ages steadily from the mid-teens to late 20's.  Despite the changes described above, the "well cared for" female face actually alters far less during this age period.  It seems that the female body works hard to maintain a youthful and attractive facial appearance when it's still very fertile.   Compared with men, facial changes are both slow and modest until fertility starts to decline substantially.  The 30th birthday is thus a traumatic time for many women as she looks in to the mirror and suddenly no longer see's back a young girl but rather a maturing woman - her lips have shrunk, the first wrinkles have appeared, fine lines have appeared at the corner of her eyes, and some sagging skin has appeared.  Even worse, she knows that others will have already seen these signs.  

Age is the foremost enemy of beauty, but ill health and overexposure to sunlight also take their toll.  Wrinkles are not due purely to chronological age.  Most skin specialists say that the majority of wrinkles are due to sunlight, as a result of constant exposure to the sun the face skin ages more quickly and more visibly than any other part of the body.  Avoiding the sun is the best way to prevent or delay wrinkles, although we do need some natural light for health, while sunbathing will considerably hasten it.

But the effects of ageing do other things to the face as well.  Gravity plays a big part.  The jowls drop and the fatty tissues beneath the skin break down as cells are replaced less often.  The face of youth is a triangle shape - at its widest at the cheekbones.  The face of age is more like a square with the chin competing for dominance.  The cheeks sink in and the skin looks less fresh because the epidermal cells have slowed down their rate of renewal.  Melanin in the hair stops renewing itself and the hair turns grey or white.  Strangely though, the eyelashes retain their colour throughout life, never turning white.

Genetics also plays a part in ageing. As melanin protects the skin from wrinkling, the people who are likely to show their age most quickly are freckly redheads, who have less melanin than others.

Good luck as regards genes, combined with a healthy lifestyle and regular exercise can delay things, but by age 30 at the very latest, even a supermodel will lose the allure of youthfulness when unaided by cosmetics, surgery and supporting garments. 

A model, before and after makeup.

With the help of such artificial aids most women seek the appearance of eternal youth - but at great and ever increasing cost in time and money.  The average American woman spends nearly one hour a day (two or even three hours isn't uncommon) on beauty care and maintaining her appearance:- bathing, makeup, hair, nails, depilating, massage, exercising, selecting her attire, etc.

Symmetry

 A key aspect to physical attractiveness is symmetry; humans, like other species, show a strong preference for individuals whose right and left sides are well matched.  John Manning of Liverpool University has reports that symmetrical men have higher quality sperm, with fewer deformed ones in the mix. He claims that symmetry is like nature’s black box - it tells you all you need to know about someone’s genetic history.

For both men and women, greater symmetry predicts a larger number of past sex partners, and a 1994 study found that the most symmetrical males had not only had more off-spring than their most lopsided brethren, but started having sex three to four years earlier!  Also, a survey of 86 couples found that women with highly symmetrical partners were more than twice as likely to climax during intercourse (an event that may foster conception by ushering sperm into the uterus) than those with low-symmetry partners. 

Studies show that highly symmetrical people are healthier, grow faster, and are better able to survive, while low symmetry has been linked to schizophrenia, mental retardation, birth pre-maturity and left-handedness.  Facial symmetry is certainly associated with health.  After analysing diaries kept by 100 students over a two-month period, researchers found that the least symmetrical had the most physical complaints, from insomnia to nasal congestion, and reported more anger, jealousy and withdrawal. 

 

Neotenous Female Face
A key feature of female facial attractiveness is the extent of neotenous (infant-like) features that the face displays.  [For more information on the form of the feminine face, see here] 

As a rule, average faces are more attractive than unusual ones but the faces we find most beautiful are not average.  When people are asked to develop ideal faces on a computer, they tend to exaggerate certain qualities.  A 1993 study used a computer program which allowed participants to morph faces until they had achieved an ‘ideal’ face.  The ideal 25-year-old woman as configured by participants had a higher forehead than an average one, as well as fuller lips, a shorter jaw and a smaller chin and nose.  She had a 14-year-old's abundant lips and an 11-year-old's delicate jaw.  Because her lower face was so small, she also had relatively prominent eyes and cheekbones.

An attractive face is not average! The most attractive face shape is not average. In one study, pictures of 60 female faces, aged 20-30 and without makeup, were rated for attractiveness by male and female subjects. An "Average" face (A) was made by blending 60 female faces into an average. An "Attractive" face (B) was made identifying the facial shape of the 15 most attractive female faces and then adjusting the average face to this shape.  90% of male and female Caucasian subjects preferred this to the average shape (A). An "Enhanced" face (C) was formed by exaggerating the shape differences between images (A) and (B) by a further 50%.  70% of the subjects preferred this to image (B). (A) Average face (B) Attractive face (C) Enhanced face

The Science of Attraction Victor Johnston, a psychobiologist at New Mexico State University in Las Cruces, found that the heart-shaped face, small at the jaw with wide eyes, combines elements that are particularly desirable to men. Johnston suggests that such features are attractive to men because they are indicative of fertility. The modified face (Femme Fertile) was constructed by warping the composite face (Plain Jane) to enhance oestrogen effects and decrease androgen effects. Androgens cause a wider and longer lower jaw, a wider nose, and more-pronounced brow ridges with thicker eyebrows (causing the eyes to appear narrower and deeper). All of these characteristics appear on male faces at puberty, and females who lack such features are found to be more attractive. Estrogens cause fat deposits on hips, breasts, and lips; this also enhances female attractiveness.

Any cues to illness or advanced age (wrinkles, grey hair, poor complexion, facial blemishes, poor teeth, etc.) are universally rated as being unattractive.  Books on the use of cosmetics are essentially manuals on how to accentuate youthfulness and the neotenous and symmetrical facial features that are known to be reliable health and fertility indicators.  With the development of plastic surgery these much desired and admired features of human female beauty can be acquired in a more permanent state, as compared to the temporary state of cosmetics.  Almost all plastic surgery attempts to correct asymmetries and exaggerate traits that are generally considered to be beautiful - and subconsciously reliable indicators of youth, health and fertility.

	Labels 1. Initial "average" male and female faces. 2. Masculine or feminine facial features and proportions added. 3. Caricature of extreme male and extreme female faces. 4. Combined morphed face
	The picture second from the left is of a woman (top) or man (bottom).  Masculine or feminine facial characteristics are progressively enhanced in the photos to the right or left.

Waist to Hip Ratio (WHR)
There's no doubt that a slim waistline between shapely hips and prominent breasts makes a woman highly appealing, this is regardless of the woman's overall body size and weight - a low waist-hip ratio is one of the few features that a tall, lean modern Barbie doll shares with a short, plump, primitive fertility icon! 

Before puberty and after menopause, females have essentially the same waistlines as males.  But during puberty waves of sex hormones start circulating in the body, high levels of the male hormone testosterone cause boys to amass in their upper body the bone and muscle of Stone Age hunters, while a high concentration of oestrogen in the female body results in the typical girl gaining nearly 35 pounds of so called reproductive fat deposited on the hips and thighs, rather than on the waist.  Those pounds contain roughly the 80,000 calories needed to sustain a pregnancy, and the curves they create provide a gauge of reproductive potential.  Devendra Singh, a University of Texas psychologist notes "You have to get very close to see the details of a woman's face, but you can see the shape of her body from 500 feet, and it says more about mate value.".  

The sex differences in fat and tissue distribution can be assessed by measuring the waist at its narrowest point, and the hip at the level of the buttocks, and computing a waist-to-hip ratio (WHR).  After puberty the female WHR becomes significantly lower than that of the male - the typical female range being between 0.67-0.80; whilst the typical male range is 0.85 - 0.95.

Studies have found a strong link between the male fascination for Barbie doll curves (or small waist to hip ratios) in women and a higher disposition of fertility and health. This male preference for women with an oestrogenized small WHR has sound scientific reasons.

Being "beautiful" in Victorian times required a tiny waist (under 20" was common!) - regardless of the damage the corset did to a woman's body internally.

A woman's WHR is a good indicator of her reproductive status.  A female with a more hourglass figure is more fertile and healthier than non-curvaceous or high WHR woman.  Almost anything that interferes with fertility - obesity, malnutrition, pregnancy, menopause - changes a woman's shape.  Healthy, fertile women typically have waist-hip ratios of 0.6 to 0.8, meaning their waists are 60 to 80 percent the size of their hips, whatever their actual weight.  To take one familiar example, a 36-24-36 figure would have a WHR of 0.67.  

Waist-to-hip ratios (WHR) reflect the health and reproductive capability of woman, those with low WHR's are judged by men to be more attractive and healthier.  Male college students were asked to judge the attractiveness of female figures that differed in WHR and breast symmetry.  Figures with low WHR's were judged more attractive regardless of their degree of breast asymmetry.  The figure with low WHR and symmetrical breasts was judged to be most attractive and youngest of all the figures.  It appears thus that men use both WHR and breast symmetry in judging attractiveness.

Many women outside this range are healthy and capable of having children, of course.  But researchers in the Netherlands discovered in a 1993 study that even a slight increase in waist size relative to hip size can signal reproductive problems.  Among 500 women who were attempting in vitro fertilization, the odds of conceiving during any given cycle declined by 30 percent with every .1 increase in WHR.  In other words, a woman with a WHR of 0.9 was nearly a third less likely to get pregnant than one with a WHR of 0.8, regardless of her age or weight.  WHR also signals health status as the incidence of certain diseases (diabetes, hypertension, heart problems, strokes, etc.) vary with body fat distribution - a high WHR indicates a greater propensity to have such problems. 

In 2007, a study by a team of Cambridge mathematicians found that it is the ratio between hips and waist that also puts a sexy sway into a woman's walk - and the nearer the ratio is to 0.7 the better.  This ratio provides the body with just the right torso strength to produce a more angular swing and bounce to the hips during the walking motion.  After studying various famous women, they concluded that the walk of actress Jessica Alba beat off rivals such as Kate Moss and even Marilyn Monroe, whose sashy along a railway platform in Some Like It Hot is one of the most famous in film history.  While Monroe was a fraction off the target ratio, Alba with a 25in waist and 36in has the perfect proportions for a sexy walk.

Jessica Alba ... walking!

Given the availability of such a revealing signal as WHR, it is not surprising that men respond by observing a woman's figure and consciously or unconsciously using it to infer her potential mating value.  Men 'biologically' prefer curvy women with a pronounced hourglass figure, since these physical features of a woman are often associated with high fertility and good health. 

Film star Marilyn Monroe, 5ft 5in tall, her "hour glass" 34/22/35 figure is extenuated by her relatively short stature. Two top models 60 years later.  (Left) Valentina Sampaio, 5ft 9in tall, with a 33/25/34 figure.  (Right) Teddy Quinlivan, 5ft 11in tall, with a 32/23/34 figure.

It is also likely that females enhance their attractiveness by emphasising and advertising a low WHR through ornamentation and clothing.  But contrary to popular opinion, the studies quoted above show that men prefer the average-sized female figure, as opposed to one that is particularly thin or fat - which may indicate fertility problems.  In addition, a higher ratio is also obviously indicative of pregnancy, which would be of particular concern to a man seeking a mate with whom to bear children!  A Weekend Post/Compas Inc. poll echoes this male preference.  More men ranked "well-proportioned curves" and "curvaceous and voluptuous" far higher that the choice of "thin and straight body like a magazine model."  

It is perhaps unsurprising to find that the voluptuous but 'wasp' waisted Marilyn Monroe has nearly perfect proportions for men.  Her weight and vital statistics fluctuated during her 20's and 30's, but her waist ratio was consistently close to 0.65 of her bust and hips.

Interestingly, women in the U.S., when asked to rate female figures toward the "ideal," consistently choose thinner figures than their male counterparts. 

Skinny is beautiful?  Women are far more likely to think so then men.

Western women are bombarded by magazine articles, advertising images and television programmes (e.g. The Next Top Model) encouraging them to diet and exercise almost to extremis in order to be beautiful - items often scripted by other women.

It would seem that the current trend for girls to diet until they become seriously underweight is more due to peer pressure from other women than from men.  Indeed, emaciated women are likely to be unhealthy and infertile, and thus offer little attraction to men seeking to mate - surviving an eating disorder (or a famine) is one of the most common causes of female infertility.  At the point where a woman drops below 5 percent total body fat, her body begins to cannibalise the less important organs for nourishment, including reproductive tissue.  It's unfortunately no coincidence that many 'coat hanger' models and stick-thin actresses have difficulty having children. 

It's no coincidence that the 2000's have seen a huge surge in transgender (male-to-female) models.  They are above average height for a woman, whilst a near-starvation diet results in a boyish and very slim build that is a designer's delight, and ideal for the catwalk.  Dozens, if not hundreds, of transwomen are working professionally as models in Europe alone - they effectively trump young cis women who were hoping to have modelling career.  Women are far more likely than men to consider these transwomen as being "beautiful", but possibly a general redefinition of female beauty is taking place - with fertility indicators such as the WHR becoming less important.
 

Breasts and Buttocks
The female breasts and buttocks are extremely potent sexual symbols of feminine beauty.  Firm but well-rounded and shapely breasts and buttocks are powerful signs of a woman's health, youthfulness, and ability to procreate.  Their sagging is also one of the first signs of aging as a girl moves into her mid-20's.

The Venus of Willendorf, carved about 23,000 BC

Archaeology seems to show that 20,000 years ago Stone Age men strongly favoured women with voluptuous breasts and prominent buttocks - which experts think were associated with wealth, health and a good diet.  It appears that for many thousands of years men looking for a partner disliked skinny women and instead competed for females that are now disparagingly called "plus size".

The perceived attractiveness and mating advantage of women with generous buxom and buttocks has almost certainly resulted in a steady increase in these features over the generations - in the fierce heat of evolution's "survival of the fittest", their size and shape has moved from a physical reproductive necessity to exaggerated exhibitionism that will help attract a good mate.

For example, only one-third of a female woman's breast tissue is associated with milk production - the rest is merely fatty tissue.  Indeed, a large buxom is actually a survival handicap to a woman, but it's also a symbol to men that she must be healthy and fit in order to be able to afford to carry such an unnecessary overhead.

A female becomes very aware of her buxom and its effect on men as she steps out of her adolescence and attains youth.  A girl gets rapid body changes between about 12 and 14 years of age - puberty - and her breasts start showing.  Between about age 14 and 18 her breasts become fully rounded, but are still pert and firm, and they reach their peak in attractiveness.  However, sometimes their growth is stunted due to hormonal imbalance, congenital defects, or deficiency of nourishing diet - this reducing the girl's attractiveness as a mate.  After 18 the breasts gradually start sagging and lose their tautness from the effects of gravity, increasing age, and (as appropriate) illness, pregnancy, breast feeding, irregular menstruation, and eventually the menopause. 

A similar process applies to buttocks - their attractiveness to men peaks in a girl's late teens, thereafter they slowly become less firm and smooth.  Girls in their thirties often start to experience unsightly skin dimpling - cellulite - this condition is related to the hormone oestrogen.  Whilst cellulite is rare in men, transwomen who have been taking oestrogen for years will also start suffering from it.

Shapely breasts and buttocks are a gift of nature to a young woman, by far the best way of maintaining these in the best possible condition through the 20's, 30's and beyond is regular exercise and a good diet.  The use of well-fitting brassieres to support the breasts from their developmental years was for a long time strongly recommended, however the medical profession has reached the opinion that bra's actually do little to preserve the shape and firmness of young breasts.  Natural aging and heredity characteristics are the primary contributors to eventual breast sagging.  The main reasons for wearing a bra are thus social pressure (women wear a bra!), improved appearance (cleavage), personal comfort, and avoiding various problems when playing energetic sports.

If all else fails, plastic surgery is an option that can dramatically improve a young woman's bust and buttocks, or help to roll-back the years for an older woman.