Chevalier Blondin was 35 years old when in 1859, with no safety harness and no net beneath him, he first tightrope-walked nearly half a kilometre across the Niagara Gorge. At different times over the coming years, he would repeat the crossing blindfolded, carrying a stove (stopping to cook himself an omelette half way), and with his manager on his back. Later on, during a visit to the UK, he crossed a tightrope while pushing a wheelbarrow with a lion in it. Chevalier Blondin was a risk taker.
In the same year as Blondin's first Niagara crossing, Charles Darwin published On The Origin of Species by Natural Selection. There may seem to be a gulf the width of Niagara between these two events, but perhaps there is more to link them than is at first apparent.
Some may find Blondin's exploits admirable and inspirational. Others may think he was mad. The difference illustrates how individuals have remarkably different attitudes to risk. Some take up extreme sports and visit war zones. Others view the ability to stay at home and live a quiet life as the happy privilege of the human species. But humans are not alone in having varying attitudes to risk. From field crickets to fighting fish and hermit crabs to hamsters, individuals differ consistently in their willingness to be exposed to risk.
Behavioural ecologists call this spectrum of responses "boldness", and researchers in the field of animal personality variation are exploring its evolutionary significance.
The first question to address is why do some individuals take more risks than others? One answer is that in some cases, bolder individuals have higher reproductive success. In rainbowfish, for example, bold males have been found to hold a higher social rank, while in guppies, females prefer to mate with bolder males. This may be because boldness can signal good body condition, or because bold males have a greater awareness of and ability to avoid local risks.
The next question therefore, is why aren't all individuals cavalier towards danger? One answer to this, perhaps unsurprisingly, is that in many cases bolder individuals also have shorter life-spans. As with many other characteristics, your level of boldness can follow various behavioural strategies for successful reproduction.
Projecting your boldness on others
In humans, different attitudes to risk can manifest themselves in unexpected ways. A recent debate over whether young children should be allowed to tackle while playing rugby at school provoked a huge and mixed response from the public. Those in favour of a ban focused on what they saw as unacceptable injuries sustained in the name of sport. Those opposed railed against restriction of liberties and championed the benefits of physicality in sport.
The size of the response at first seemed disproportionate, even distasteful, given other news items in the headlines. In particular, it seemed strange that those voicing these opinions were concerned about risk in the abstract, rather than to themselves directly.
But perhaps we could think about how evolution might play a part in this debate. Humans are a fiercely social and cooperative species and protecting members of our close social group has a sound evolutionary basis. By reducing risks to those with whom we share genes, more of our own genetic material is preserved. We're also a species that cooperates to raise its young. Having a strong social group increases the chances of breeding successfully ourselves.
At the same time, it's too simple to say that those against a ban on tackling are just dismissing the dangers posed to children. Taking evidence from other species, such as three-spined sticklebacks, higher boldness is associated with higher aggression. In this case, the researchers suggest that individuals who are more exposed to risk cope with this by responding more aggressively and so more boldly to threats. Humans today usually constrain their aggression within carefully outlined legal and social rules. But perhaps the aggressive elements of rugby still scratch an evolutionary itch inspired by an individual's impulse to be bold.
Boldness is rarely studied in this way in humans, and the examples above are strictly hypothetical. But they are intriguing to consider the next time you and your friends find yourselves in a ferocious argument over something as seemingly minor as school rugby. Perhaps the reasons can be traced back to Darwin, and your differing opinions can be seen as markers of our evolutionary past, present and future.
Explore further: Schooling fish: Wild zebrafish assess risk through social learning