The joy of steps: why humans are built to get a high from being on the move

More armchair athlete than super-speed sprinter? Fear not - a dopamine reward can still be yours thanks to the way humans are adapted for movement

The sporting excitement of the 2016 Olympic and Paralympic games is now a distant memory, and our attention has long since shifted back to the ups and downs of our own generally unathletic lives. After such a lavish celebration of physical achievement it can be quite a come-down. But from a certain point of view, it’s strange that the physical prowess of humanity should be cause for celebration at all. By the standards of the rest of the animal kingdom, Usain Bolt’s performance is nothing to shout about. Is it not baffling that the athletic elite should receive such adulation when it’s in the mental sphere that our species excels?

Such thinking neglects the enormous influence of the drive to move on the evolution of Homo sapiens, an influence that extends far deeper than the famous freeing of our hands and their opposable thumbs that occurred when our ancestors became full-time bipeds. Indeed, the opposable thumb itself likely developed as an adaptation to safe movement in the trees tens of millions of years before our forebears hit the savannah. But more importantly, our psychology is still adapted for a life on the move, even in the least energetic among us. Understanding how may help us to live more joyful lives.

The most well-known psychological movement-driver is surely the runners’ high – a sense of well-being and euphoria that can be engendered by endurance running. These feelings used to be attributed to endorphins, but we now know that chemicals called endocannabinoids (eCBS) are largely responsible. Named after their resemblance to the active ingredient of cannabis, eCBs are powerful pain-killers that additionally cause the release of the neuro-modulator dopamine in the brain.

Dopamine is usually described as a “reward chemical”, whose evolutionary function is to give us an emotional hit when engaged in activities that are likely to improve our reproductive success. The runners’ high makes perfect sense in this light. Our African ancestors probably used a persistence hunting technique – running after their prey for hours until it dropped from exhaustion – as do some hunter-gatherers today. A feel-good dopamine incentive was undoubtedly vital in maintaining the required pace.

Unfortunately for many of us, a high level of aerobic fitness is a necessary precondition of the runners’ high. Attempting a prolonged run without it causes a build-up of lactic acid and the activation of our emergency emotional overrides long before the eCBs kick in, and we just feel grim. However, there are gentler ways of using movement to get a dopamine hit.

In recent years a range of techniques have been developed to find out exactly how dopamine’s emotional bribery works in animals. Fast-scan cyclic voltammetry uses electric currents delivered through carbon-fibre electrodes inserted into the brain to measure changing dopamine concentrations over split-second timescales. The method of optogenetics lets an experimenter tinker with an active animal’s dopamine levels, by first infecting it with a genetically engineered virus that causes dopamine-secreting cells in its brain to become light-sensitive; these cells can then be controlled with flashes of light in implanted optic fibres.

Both of these techniques were recently used by Arif Hamid and colleagues at the University of Michigan to see how dopamine influences the behaviour of rats. The rats in question were trained to carry out what was essentially a treasure hunt: a sequence of movements guided by visual and auditory cues, which if followed correctly resulted in the delivery of food. Hamid found that the dopamine concentration in the brain increased sharply every time a rat registered a cue and embarked on the next stage of the sequence. If the dopamine concentration was artificially increased using fibre optic implants, the rats showed a greater propensity to begin the hunt, and learned the meaning of the cues more rapidly.

These results tell us that dopamine’s role is more nuanced than was once thought. Rather than acting as a general reward, it appears to be a specific motivator of motion, encouraging an animal to work for what it wants. But motion alone is not enough. The correlation between dopamine release and the presentation (and learning) of unexpected cues indicates that active exploration – a pursuit with obvious adaptive value – is the key stimulator of its release.

The upshot of all this is that you don’t have to be a distance runner to experience the dopamine high. Walking will do as long as it’s used to explore, so full sensory engagement – present moment awareness if you will – is a must. This will come as no surprise to hunter-gatherers: engaged locomotion is what they do all the time, and many anthropologists have noted the emotional rewards they draw from their wanderings. But in our civilised world of cars and sat-navs, in which personal exploration on foot seems pointless, most of us seriously underestimate the pleasure that the simple act of movement might bring.

So why not find the time to go for a wander every now and again, minus navigational technology and rigid destinations. With luck, you’ll soon discover that the ancient joy of motion is still very much ours for the taking.

Matt Wilkinson’s Restless Creatures, published by Icon Books, is available for £8.19 through the Guardian bookshop.

Matt Wilkinson

The GuardianTramp

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