The differences between males and females go far beyond the obvious, and in some quite unexpected ways.
Men are different from women – from the bones out. Some of the differences such as their whiskers and Adam’s apples are easily recognised, while others such as their strength and ability to build muscle are well known. So, apart from the obvious, how do the sexes differ?
Bone size
Male bones are generally longer and larger than female bones and have more obvious muscle markings. Even before birth, male babies have longer forearms and ring fingers than girls, and the difference in the pelvic girdle is the key to identifying gender in skeletons. The male pelvis is longer and heavier than the female. At puberty the shoulders grow more massive, giving males the typical triangular silhouette of wide shoulders and narrow hips.
Men also have bigger skulls, with more prominent brow ridges and mastoid processes (bumps behind the ear). They also tend to have bigger jaws, chins, cheekbones and noses, giving men’s faces a squarish shape and stronger features than women’s.
These differences in bone structure are hormonally triggered at puberty. Increased levels of testosterone trigger the growth of certain bony facial features so boys’ faces grow more than girls’. Female faces remain relatively childlike. High levels of oestrogen in growing girls prevents the growth of facial bone and results in increased thickness of lips and fat deposition in the cheek area, whereas a male face is often ‘chiselled’ in appearance.
This gender difference comes at an evolutionary cost because testosterone decreases the effectiveness of the body’s immune system – only healthy individuals with high-quality immune systems can afford to produce the hormones required to produce masculine characteristics.
Faces with masculine features – such as a large jaw and prominent cheekbones – appear dominant, and dominance is associated with male reproductive success in many species, including humans.
However, a recent study by researchers in Germany and the University of Cambridge in the United Kingdom suggests the original dominant male primate features of prominent canine teeth and an elongated face were not as attractive to females as features such as broad cheekbones, considered appealing today.
‘Our research suggests that in early humans a face that was attractive as opposed to aggressive conferred an advantage,’ says Eleanor Weston at the Research Institute Senckenberg in Frankfurt.
By analysing the shapes and sizes of facial features in chimps, gorillas and other primates, the team found evidence suggesting our ancestors may have gradually sacrificed fighting for wooing, with females preferring broader faces with prominent cheekbones, not unlike those of contemporary movie stars such as Johnny Depp, Orlando Bloom and Viggo Mortensen.
While females may have held the balance of power in the evolution of handsome faces, they are the losers when it comes to ageing of the facial bones.
Using CT scans of 100 men and women, researchers at Duke University Medical Center in the US discovered that the bones in the human skull change as people age. The forehead moves forward while the cheekbones move back. As the bones move, the overlying muscle and skin moves as well, subtly changing the shape of the face.
‘The facial bones also appear to tilt forward as we get older, which causes them to lose support for the overlying soft tissues,’ says Dr Michael Richard, an oculoplastic surgeon at the Duke Eye Center. ‘This results in more sagging and drooping.’
The dramatic ageing of facial bones also happens at a significantly younger age for women than men, according to Dr David Kahn, assistant professor of plastic and reconstructive surgery at Stanford University School of Medicine in the US. Women’s facial bones begin to shrink at the onset of early middle age, while men don’t exhibit this until they are at retirement age.
Musculature
Men are not just bigger than women; they are much stronger, almost twice as strong in terms of hand grip, upper body strength and lifting ability. This is because they have bigger muscles, especially in the upper body. Males tend to be more muscular than females from birth, with girls showing a higher fat ratio even before puberty. At puberty, males begin to develop heavier bones and thicker muscles. The average adult male has about 150 percent of the lean body mass of an average female, and about 50 percent of the body fat.
Because men have bigger muscles than women, this also affects the facial contours, especially in relation to the jaw and neck. It is the difference in their muscle development that makes males’ Adam’s apples protrude. Men characteristically have thicker necks than women, and often the masseter muscles at the hinges of the jaw are also more prominent. Cheek and forehead muscles can also be more pronounced.
Their muscle size affects the appearance of men’s faces, providing a more sculpted look than is usually seen in women.
Even the nerve impulses that control muscle movements differ between the sexes: men and women have different left- and right-brain connections that affect the face. In right-handed individuals, men have stronger left brain to left side uncrossed cortico-muscular projections and women stronger right to right.
While men have larger muscles, women are more facially expressive, suggesting that they may use their facial muscles more. This gender difference is present from birth; girl babies smile more than boys do. While many of the 53 facial muscles are involved in conveying the universally recognised expressions of anger, happiness, surprise, fear, sadness and disgust, not everyone has the capacity for the same muscle movements. A study by Dr Bridget Waller from the Centre for the Study of Emotion in the Department of Psychology at the University of Portsmouth in the UK, in collaboration with anatomists at the University of Pittsburgh and Duquesne University in the US found there are 19 facial muscles that may not be present in all people and that only two-thirds of the population have the risorius muscle that creates an expression of terror.
It is tempting to speculate that the manly quality of maintaining a stoical countenance under challenging circumstances may not be merely innate, due to their lesser expressiveness in general, but possibly also because they are unable to form some expressions. In both men and women, the facial muscles elongate with age and the average man’s facial muscles will be a centimetre longer at 55 than 30 years earlier, contributing to sagging of the facial tissues and the formation of creases and wrinkles.
Skin
Men’s skin is different from women’s in a number of respects, the most obvious being facial and body hair growth. Men’s beards and body hair growth are triggered by the hormone androgen, and its continued action causes the hair to become thicker as the young male matures.
They also have more sebaceous glands than women. Testosterone gives men a 70 percent higher sebum production than women, which diminishes with age but still contributes to maintaining the emollient film of lipids on the skin’s surface. While this keeps their skin naturally lubricated, it also means they have larger pores and sweat more, making their skin ‘dirtier’. To an extent, shaving compensates for this by mechanically exfoliating the lower face, but cleansing should be an essential part of male skincare.
Men’s skin is not only more lubricated, it is also denser. While women’s skin is characterised by a smooth surface and plump texture, due to the underlying fat, men’s skin contains more collagen, the fibrous protein that makes up the skin’s connective tissue. This gives men thicker skins and is the reason they can appear to age more slowly than women, whose collagen production drops dramatically at menopause.
But there is a balancing factor. Women’s external fat is much healthier than the internal fat even apparently slim men can carry in their muscles and around their vital organs, including the heart. This tendency is partly governed by lack of exercise and partly by genetics. ‘Our work so far has shown that you can take two men of the same age, with the same BMI (body mass index), and find one with 5 litres of fat within him and another with 2 litres,’ says Professor Jimmy Bell, head of the molecular imaging group at the Medical Research Council’s centre at Imperial College, London.
‘We’ve even scanned people who are underweight and found up to 7 litres of fat inside them.’ Bell has coined a term for these individuals, calling them ‘tofis’ – thin on the outside, fat inside. The good news is that the way the body stores fat can be altered by changing the diet to one containing grains and lentils.
Another structural difference in men’s skins is its vascularity. The fine network of blood vessels below the surface is more extensive, making men more prone to bleeding and to appearing ruddy faced. Abundant blood supply is essential to healthy skin functionality, even if it does make the practice of shaving a daily challenge!
While women may be the fairer sex, men do enjoy a number of advantages over women including, apparently, the ability to adapt to attract their mates.
