Although some of the events of the past week or so have made me want to go back to bed and hide under the covers (out of embarrassment and denial), it’s impossible not to write about the race riots at Cronulla.

There’s the cringe factor, wondering what the rest of the world must think of us (and how it will affect our relations with them). There’s the element of fear, that this kind of sentiment is what led to the Armenian Genocide, the Holocaust, and other race/creed-based genocides. The fear that until it’s over, there’s no way of knowing how far it will go.

But beyond that, I have to wonder why this kind of thing happens. Psychology of mob behaviour is complex, and it can cascade quite unbelievably: see Mass hysteria at Melbourne Airport. But I’m not just talking about the actions; I’m talking about what makes a neo-Nazi, a white supremacist, or even what motivates a teenage boy to write “we grew here, you flew here” in permanent marker on his chest.

A letter in last week’s New Scientist, Born to be good, made me think. The letter is about cooperative behaviour in animals and humans (if you want to make a distinction); the author believes that moral behaviour is behaviour that strengthens the group. Critically, he describes the hunter-gatherer mentality as “cooperative, comradely, compassionate and, if necessary, self-sacrificing, as well as hostile to outsiders [my emphasis]”. Xenophobia is so ubiquitous; it has caused so much bloodshed and has hardly helped civilisation as a whole. But what if it’s an evolved trait; something that’s in all of us, and the only variation is the degree to which we use our rationality to disarm it?

It’s not a happy thought. It might just be enough to really make me want to go back to bed.