Free solo style climbers need their heads examined. That seems to be the premise of the investigation reported here. Alex Honnold does amazingly scary things in his solo climbs, all without ropes or any kind of effective protection. Just watching, or just looking at pictures, is enough to make most of us shudder; a neurobiologist came to the conclusion that Honnold’s amygdala wasn’t working.
Why would he think that? The amygdala, or amygdalae, are two small organs within the brain that are generally considered to have a role in producing fear and aversion. A friend of mine once suggested they could be renamed after the moons of Mars as Phobos and Deimos – ‘Fear’ and ‘Loathing’ in Greek. In fact that wouldn’t be at all accurate, not least because the left amygdala seems to produce positive emotional reactions as well as negative ones. The broad initial analysis of Honnold’s behaviour seems to have been that his rational cortex was getting him into perilous situations because his amygdala was failing to wave the red flag. In some ways that seems odd: I think my rational, future-planning cortex would keep me the hell away from anything like the cliff faces Honnold climbs, while it might be the emotional thrill-enjoying parts of my brain that impelled me towards them.
A scan revealed that Honnold’s amygdalae were both present and correct, without any signs of damage; however, they didn’t seem to respond to various scary or unpleasant pictures in the way a normal person’s would. This knocks out one strong version of the theory. If there had been visible lesions in Honnold’s amygdalae, there would have been strong reason to suspect that his behaviour stemmed from that damage; but we knew already that he isn’t as scared as the rest of us, so finding that his amygdalae react less than most merely gives us another version of the finding that mental differences are associated with brain differences and vice versa. We sort of knew that; if that’s all we’ve found out we’re sailing dangerously close to the sea of neurobollocks and scannamania.
It is possible to do without amygdalae altogether. SM is a patient reported on by Damasio and others, who lost both amygdalae as a result of Urbach-Wiethe disease. She did not take up free solo style climbing or other dangerous sports, but she shows a distinct lack of fearful and aversive reactions to strange people and other triggers of fear and distrust. She has suffered a number of violent encounters which might partly have been the result of the lack of fear which allowed her, for example, to walk through dubious parks at night; but it may also arguably have got her out of some dangerous situations through her panic-free Spock-like calm and non-hostile responses. It seems she lives in an area where violent crime is common in any case, and she has succeeded in bringing up three children independently.
It could be that amygdalae function somewhat differently in men and women, which might explain why Honnold’s supposed problem results in dangerous activity while SM’s mainly lead her to hug and trust strangers. There are known differences in the pattern of development; female amygdalae develop fully earlier, while male ones go on growing longer and end up bigger. Those differences might simply reflect general differences in growth pattern, though there is also some evidence of different patterns of activation; it’s possible, for example, that the activation of female amygdalae tends to promote thought while the male equivalent promotes action. All the usual caveats apply and great caution is in order. Let’s also remember that SM and Honnold are both one-off cases; that SM suffered damage to other parts of her brain – and that Honnold says he does feel fear, and that his amygdalae appear to be perfectly normal.
Are they though? The research showed an almost total lack of response to pictures of terrible injuries and other things that would normally be expected to evoke a strong reaction from the amygdala. So perhaps there is something abnormal going on after all? Maybe there is damage too subtle to detect? Or maybe something is suppressing the amygdala?
The identification and handling of threats by the brain is actually a complicated business. Many quite low-level systems as well as highly-sophisticated ones can make a contribution (a sudden loud growl can cause a wave of fear; so can a few quiet words from a doctor). The role of the amygdala seems to be as much to do with memory as fear; it pays attention to things that we have found are associated with really bad (or sometimes good) experiences and helps direct our attention to the right things, reminding us to look at people’s eyes when we want to assess whether they are frightened, for example. The interplay may be very complex, but even on a pretty crude interpretation there might be conscious processes that sometimes shut the amygdala down:
Visual: furry, claws, animate, ursine: yup, over 99% positive that’s a bear. Hey, amygdala, big animal for you?
Amygdala: OMFG run for our life!
Cortex: guys, this is a zoo, there are bars – Visual, confirm stout bars – OK. Amygdala, STFU.
It doesn’t always work like that, of course. Cortex knows that we can happily walk along a narrow plank no wider than the terrifying Thank God Ledge if it is a few centimetres off the ground, but saying so repeatedly will not stop amygdala sounding the alarm.
Ultimately it may be that Honnold’s different behaviour and different amygdala activation are simply two facets of his different personality.