Is it courage or broken amygdala?
Alex Honnold is the only person that ever free-solo El Capitan. This article from the Alpinist actually talked about the technical aspect of the ascent instead of just gushing.
http://www.alpinist.com/doc/web17s/n...freerider-solo
tl;dr
The planning took around 8 years with 2 years of rehearsal. He did the 3,000-foot climb in 3:56. To put it into perspective, in 2015 it took Tom Caldwell and Kevin Jorgenson 19 days to free-climb El Capitan. Caldwell and Jorgeson used no climbing equipment, just ropes and harnesses to prevent deadly falls. None of that for Alex Honnold. The climb is rated 5.13a (5.14 is max difficulty and usually involves weather/snow/ice).
The question is then what makes this person tick? In 2015, they did an MRI of his brain while he was subjected to both stress and reward tests. Keep in mind this is not an exhaustive study, and his brain activities was only compared against one baseline subject (another high-risk sensation seeking climber).
http://nautil.us/issue/39/sport/the-...t-solo-climber
tl;dr
He does have normal amygdala.
During the stress test, they could not detect any activities in his amygdala region.
For the reward test they were looking at his nucleus accumbens brain apparatus. Again no reaction. It is possible that they choose the wrong reward to motivate him. To a 31 years old guy who chose to live out of his van, money probably does not mean much.
In the end, there was no clear anwer. The experiment was pretty crude. It definitely won’t stand against thorough scientific scrutiny. Still it does provide an insight into the only person who had ever free-solo El Capitan.