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Author Judy Wearing explores the evolution and culture of human hair, from baldness as a masculine trait to pubic hair as a possible detector of infidelity.
A new book reveals that baldness is about as male as it gets and that pubic hair may act as a cheating detector. Judy Wearing, an author and editor, explores these ideas in Anxious and Hairy: The Evolution and Culture of Human Hair.
The book examines the dense and layered place of hair in human history and psyche. The research began when Wearing was a PhD student at Oxford studying mating behaviour. She was struck by a simple question: what was the purpose of pubic hair, armpit hair, and each of our body's furry patches? The published literature failed to produce satisfying answers, so she began her own investigation.
Some 30 years later, she is still tangling with those questions. Hair, or fur, evolved about 245 million years ago with cynodonts. These were the warm-blooded reptilian ancestors of all mammals, including humans. They had fur for insulation, preventing heat from escaping their bodies.
Fossil evidence of the wolf-like Cynognathus suggests it also had whiskers, which are super sensitive tactile hairs that provide valuable sensory input. The protein keratin is integral to human hair, skin, and nails. It is also the basis for cat claws, bird feathers, sheep wool, and much else besides. Hair growth is an evolutionary modification of an ancient skin-development process by which reptiles grow scales, Wearing explains.
She says you can think of hair as kind of long, thin scales, in a way. Both are made of keratin. Cells called keratinocytes are generated from the very base of the hair root. They push older cells higher inside the tubular follicle.
Mammary Glands And Hair Follicles
As they pile up, dead keratin cells fuse into shafts, breaking the skin and becoming visible as hair. Each hair follicle functions like a mini organ, Wearing says, with its own set schedule of growth and resting phases. Like fur, the ability to produce milk is another defining trait of mammals. The two are more closely associated than you may think.
Mammary glands evolved as an adaptation of certain hair follicle glands. In Australia, the echidna and the platypus embody the evolutionary path before it diverged. Though they lay eggs, they also nurse their young via specialised milk-secreting patches of fur on their bellies. Though we might appear wildly less furry than our primate relatives, Homo sapiens have the same number of follicles.
They are found everywhere except the palms and soles. Wearing says we have as many hair follicles as chimpanzees: two to four million of them. The difference is that the majority of human hairs are very thin and fine. These shrunken vellus hairs that cover the body are distinct from terminal hairs.
Eyebrows Protect Eyes And Communicate
Terminal hairs are the thicker, stiffer, and more pigmented strands growing in what Wearing terms strategic locations. These include the eyebrows, armpits, and groin. The constellation of these patches is unique to our species, but there is logical function underpinning each one, Wearing says. Eyebrows evolved to protect our eyes and communicate social information.
Wearing asks when was the last time you remember flashing your eyebrows. We do not know we are doing it, but we are reading those signals all the time, she says. There is also a rich history of refining them through beauty practices. Shaping eyebrows to be thinner, as has often been the style for women, gets interpreted as submissive and friendlier, Wearing says.
In ancient China, there was a 1,000-year-old tradition of removing all the hairs to paint on an altogether new shape. This was done in painstaking symmetry and often non-natural colours. Today, one fashion for brows is to stop them from moving, using Botox to prevent wrinkles. But as Wearing points out, this has indirect implications for our communication too.
Botox Impairs Empathy And Emotions
Psychologists have found that the popular cosmetic procedure impairs our ability to mimic others emotional expressions, which curbs empathy. It sounds dystopian, but there might actually be positive consequences, Wearing adds. Botox is being studied as a potential treatment for depression by interrupting the feedback loop by which we experience and express emotions. Underarm and body odour are huge in our social communication, says Wearing.
Our armpit strands are stiffer than those in other places, causing them to stick out and broadcast our particular chemical blend. Research suggests we can sniff out not only each other genetic differences but emotional states and even health. This exchange largely happens below our conscious awareness, Wearing says. Most of us never think you smell anxious, but we might think you look afraid.
Though men and women have the same average number of follicles on their faces, the majority of adult men grow terminal hairs rather than the more typically female peach fuzz. The density is determined by genetic and hormonal differences, with beard and moustache hairs regulated by testosterone and dihydrotestosterone. It is likely that facial hair evolved as a means to compete against sexual rivals and communicate dominance.
Baldness Linked To Testosterone And Masculinity
There is even a suggestion that beards provide some protection to the jaw in the event of a punch-up. Balding is not so bad. Hair loss is commonly a source of anxiety for men, but Wearing argues that baldness is about as male as it gets. The trait is linked to testosterone and is often seen as a sign of masculinity.
The book also explores why some gentlemen really do prefer blondes and the reason we evolved to have eyebrows. Wearing says a lot of these questions have never actually been looked at by researchers.
Human Hair Evolution Biology Keratin Mating Behavior Human Hair Evolution Judy Wearing Baldness Masculinity Pubic Hair Cheating Detector Anxious And Hairy Book
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