Sea Monsters & Hypertension

As a young man I loved to swim in the sea alone. You're not supposed to do this, the life savers tell us not to, but there's something about it that makes you feel amazing. At least, that's how I used to feel. Because one day, a dozen years ago, I went for a swim at Bawley Point on the south coast of NSW and something happened. I was snorkelling across the bay about a metre from the bottom when I saw something. It was a stingray, not fully grown, and it saw me at the exact same moment that I saw it - we arched upward and away from each other at the same time.

The ray was beautiful, it looked hydrodynamically perfect and moved effortlessly. But that's not what struck me as soon as I got to the surface. Instead I became horribly aware that not only was I the only person in the water, there was nobody on the beach or rocks either. I don't think I've ever swum quicker.

I don't swim alone in the ocean any more. It's not that I fear another encounter with a stingray - it's sharks that I worry about now. I don't remember worrying about them before, but these days I do - just for a moment - every time I go into the sea. I'm careful not to get too far from everyone else because I figure why narrow the odds?

The fear of sharks is one of a larger group - the fear of being eaten alive. This fear is an ancient one. It's up there in the amygdala, that part of the brain we got from reptiles, and for most of human history it's been a real asset. It's helped to ensure that my ancestors and yours survived long enough to reproduce - which has worked out well for both of us.

But these days my chances of being killed, let alone eaten, by a shark are close to zero. They're higher than being killed by a lion - Australia doesn't have lions except in zoos and I still go to the beach in summer - but they're still very, very small. I'm much more likely to drown than be attacked by a shark. And many times more likely to killed in a car crash than drown. Actually the drive to and from the beach is the riskiest part of the whole day.

However, it doesn't feel like that. Lizard brain has nothing to say about driving - but quite a bit on the subject of being attacked by a shark. Both risks are small, but one is orders of magnitude smaller than the other. Perversely, this is the one I worry about.

If I really want to worry about something that will kill me, I should lose some weight. If I lost 13.6% of what I weigh now I'd be healthier. (I'd also look amazing in the shower). My family history contains hypertension, diabetes and obesity - not a trifecta I'm keen to encounter. Diseases of affluence - caused by eating too much and moving too little - are the big killers in Australia. (They're not doing the country any good either) They're what I should be worrying about and that worry should change my behaviour.

But lizard brain is not frightened of eating too much and completely unperturbed by the idea of moving too little. It's doing me no favours.

In short, I worry unnecessarily about very unlikely events and ignore genuine dangers because it's the unlikely events that push my emotional buttons and the genuine dangers that don't.

Dan Gardner, the Canadian journalist, manages to make perfect sense of all this in his book, "Risk: The Science and Politics of Fear". I've spent the last week devouring it and interviewed him this morning. You can find it here.