86Thousand400: Fighting our Instincts

The human body is built for regular physical activity.

10,000 years ago everyone was a hunter gatherer and life was marked by periods of intense physical activity followed by days of rest.

Our average energy expenditure per unit of body mass is less than 38% of that of our Stone Age ancestors. And I think it's fair to say that our calorie intake has increased quite a lot. The kicker is that even if we followed the most demanding governmental recommendations for exercise and logged 30 minutes of physical activity a day, we'd still be at less than half the energy expenditure for which our genes are encoded. Palaeolithic man had to walk 5 to 10 miles on an average day, just to be able to eat.

Today we don't have to expend much energy to find food, and we certainly don't have to use our brains to figure out how to get our next meal. The situation has come about only in the past century or so, but it takes tens of thousands of years for our biology to evolve - there's a mismatch between our lifestyle and our genes.

In the context of stress, the great paradox of the modern age may be that there is not more hardship, just more news - and too much of it. The 24/7 streaming torrent of tragedy and demands flashing at us from an array of digital displays keeps the amygdala flying. The negative and the hectic and the hopeless heap on the stress, but we figure we can handle it because we always have. Up to a point. Then, we just want to relax and take a break, so we grab a drink and plop down in front of the TV or go sit on a beach somewhere. It's no wonder that obesity has doubled in the past twenty years - our lifestyle today is both more stressful and more sedentary.

Adding physical activity to our lives, we become more socially active - it boosts our confidence and provides an opportunity to meet people. The vigour and motivation that exercise brings helps us establish and maintain social connections

If you exercise or even just socialize, you're tapping into the evolutionary antidote to stress