Yes, they usually kill fewer people each year than bee stings, quad bike accidents, drownings, and most other mortal threats.

But the threat of a shark attack, while miniscule, captures the mind like few of these things, setting off a response in the amygdala, the part of the brain where fear is felt, and quickening the pulse.

There have been six fatal shark attacks in Australia so far this year - an unusually large number. So for Saturday's Weekender magazine, I set out to figure out: is the fear of sharks rational, or not?

It started with a conversation with two surfer friends at the beach on Monday as the shark mesh contractor pulled three tiger sharks out the nets at one of my local beaches. I swim there regularly with my kids. I'd been in at the next beach around several days the previous week.

Two of the sharks were 3.8m, causing us to wonder if they were some of the beasts spotted feeding on a whale carcass washed up at Bulli a few days before. It was a great scene there as the whale attracted the sharks, which attracted hundreds of people, whole school classes, hoping to catch a glimpse.

Now I don't mind admitting I'm afraid of sharks. Very afraid. It's such that I'm never comfortable out of my depth behind the waves, and often when diving under a wave I imagine I'm about to come face to face with a big toothy grin and a pair of those dark, almost vacant, singular purpose eyes.

It's such that swimming from a friend's boat to the shore on the Hawkesbury, I couldn't help but panic a little, imagining what might be coming up behind, and accelerate. I wouldn't admit, however, that I've even felt the shark fear while swimming in the local ocean pool, because that would be ridiculous.

OK I will admit it - to show that in many ways fear of sharks is irrational. Back to the surfer friends at Austinmer beach. They were heading in for a swim as soon as the shark boat had gone. Sounds silly, but I thought they were much more realistic than me - making decisions based on the real chances of something happen, rather than the Amygdala Rules where fear shouts loud.

Two marine science experts I interviewed said fear is one of the traits that has helped keep us humans alive. Any creature that doesn't sense fear had better grow some serious armour. And a large creature that appears from out of nowhere trying to rip you up with his terrible teeth is a pretty nasty thought.

Does the six fatal attacks this year signal something new? Is there evidence to show shark numbers are on the rise? The short answer: it's complicated. The long answer is Saturday's Weekender feature story.