Born to run: The intriguing history of sprinting, sweating and ‘nature’s jockstrap’

Two main types of sweat glands evolved: apocrine and eccrine (both words derive from a Greek root for “secretion”). The apocrine gland is embedded deep in the skin, always adjacent to a hair follicle, and produces a viscous fluid that coats the hair shaft.

Apocrine glands are concentrated in thickly hairy areas such as the armpit. Bacteria, not the apocrine fluid itself, cause the funky but sometimes-sexy smell that can emanate from here. Eccrine glands are far smaller in size and more numerous: one has four to six million of these, each opening to the skin’s surface through an individual pore. Eccrine glands are our primary agents for cooling; they produce a watery, slightly salty fluid, and are found on every surface of the body except in three extra-sensitive spots: the lips, ear canal and the outermost portions of sexual organs – the head of the penis and the clitoris. They are most prevalent on the palms, soles of the feet and forehead.

It may even be that being athletic – running, climbing, building muscle – was critical to the increase of mental capacity and brain size in early humans.

Sweat glands are formed in utero, all several million of them. They are fully intact at birth, so sweating can be detected within the first few days of life – if not the first hours. What one may see and feel an infant experience right away is what is called emotional sweating: sweating triggered by pain, fear, anger, panic, nervousness, any powerful emotion. Even ecstasy, I suppose. While thermal sweating occurs over the entire body, emotional sweating is confined to the forehead, armpits, soles of the feet and palms.

Like thermal sweating, emotional sweating evolved in early hominids most likely as part of the fight-or-flight response. Having damp palms and soles actually aids in gripping if one is on the run, climbing, or throwing – something that athletes know intuitively. This is why baseball players spit in their hands before batting or pitching. As for a dripping wet forehead, one theory suggests this is a kind of corporeal SOS: a sign, right at eye level and immediately recognisable to others of your kind, that you are in distress – a silent scream spoken in beads of sweat. Wet, odoriferous armpits likely evolved to serve a similar function, communicating emotional states via both the visual and the olfactory systems. At such moments, fear – and desire – really can be smelled.

The fossil record reveals much about our evolution as bipeds – but only so much. While bits of bone tell us that early hominids could run and did run (undoubtedly because they had to run), what’s left unsaid is whether they sometimes chose to run. Did they ever run for exercise or pleasure, to use the modern terms?

Those who deplore running would likely say there’s no way that a prehistoric man, woman or child would go running for no reason other than for the sake of running. But I beg to differ. What I find when I go for a run is that I am conscious of the world, the natural world, in totally different ways than when I am walking. It is uniquely pleasurable. I am conscious of wind, of running against the wind – its force – and of the wind behind me, and of the sun, of its perfectly circular shape, and its heat, its warmness on my body, and the shadow it casts in front of me. I am aware of the ground, the earth beneath me, and of how changes in terrain register instantly at the soles of my feet.

I will run until I feel tired, until I’ve had enough, and then I will go just a little farther, at which point a wave of wellbeing washes over me. This is not coincidental. My brain is rewarding me for doing something gruelling that is beneficial to my overall health – and providing an incentive to do it again. Sustained activity triggers the release of specific neurochemicals, endorphins, which have a kind of tranquilising effect.

On Greek vases, we see them running, their genitals exposed. It’s as if these tender parts of the body were not tender in the least, but tough enough to be knocked around.

On top of that, the body gets a deposit of human growth factor, a repairer of muscle tissue, as well as specialised proteins that, according to new research, are involved in the creation of neurons and the connections between them, synapses. It may even be that being athletic – running, climbing, building muscle – was critical to the increase of mental capacity and brain size in early humans: physical activity as a driver of human intelligence, not the other way around.

Some of the earliest recorded instances of running are found in Egyptian wall reliefs dating as far back as 1500BC, long before the first Olympic Games were held. These runners were invariably depicted wearing the equivalent of shorts or a loincloth. Not so the Greeks, as is well documented. That male athletes competed in the nude is something we accept today without question, more as historical fact than as anomalous behaviour. On Greek vases and amphorae, we see them running, wrestling and boxing, their genitals exposed. In these depictions, it’s as if these tender parts of the body were not tender in the least, but tough enough to be knocked around, crushed, jostled, boxed, hit. Or that whatever damage was done was worth it for the sake of the physical performance – or the sheer beauty of it.

All of this raises a question: can one actually run a race without athletic support? I had to find out for myself. My partner, Oliver [Sacks, the late neurologist], had a home in the country on a large piece of land. The driveway alone was a quarter of a mile long – perfect for putting my question to the test. One day I shucked shorts, underwear and shirt. I kept my shoes on, the supposed advantages of barefoot running notwithstanding, and took off. There was some jostling down below, some definite – what’s the right word? – bouncing. But within seconds, my testicles retracted and scrotum followed, as if shrink-wrapping my balls, the two now vacuum-packed within the lower abdomen. My penis contracted to a fraction of its normal size. It was as if a message had been sent to the nervous system by wire: pack it up quickly, boys. I found myself sporting nature’s own jockstrap.

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I ran to the end of the drive and turned around. The sun warmed my whole body and into my insides. I ran my hands over my skin and slopped up the sweat: a manual strigil. Jogging had passed the test, but what about sprinting? I did a 100-yard dash back to the top of the drive, unbothered by the slight flopping. If anything, I found it comical, how my genitals now resembled a bell, a very small bell. Beyond this, what I felt deeply was something vital, wild, powerful – more hunted than hunter: I felt, in a word, like an animal. I turned and sprinted back down the drive as fast as I could.

This is an edited extract from Sweat: A History of Exercise ($30, Bloomsbury), by Bill Hayes, out now.

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