America had, for one thing, lived in anarchy for - until much more recently than Europe. We had the Wild West, where the cliche of the cowboy movies was the nearest sheriff is 90 miles away, and so you had to pack a gun and defend yourself.

Human nature is complex. Even if we do have inclinations toward violence, we also have inclination to empathy, to cooperation, to self-control.

People have long assumed that violence is necessary for political change. Rulers never cede power voluntarily, the argument goes, so progressives have no choice but to contemplate the use of force to bring about a better world, mindful of the trade-off between a small amount of violence now and acceptance of an unjust status quo indefinitely.

The supposedly immaterial soul, we now know, can be bisected with a knife, altered by chemicals, started or stopped by electricity, and extinguished by a sharp blow or by insufficient oxygen.

Human evolution, at first, seems extraordinary. How could the process that gave rise to slugs and oak trees and fish produce a creature that can fly to the moon and invent the Internet and cross the ocean in boats?

If you look in general at people who live in anarchy, they have quite high rates of death from either homicide or warfare or both. Anarchy is one of the main reasons for violence, and it may be the most important.

Photography is a demanding action sport. The light can change so quickly. I often find myself sprinting so that I can catch the perfect light falling on a photogenic subject.