>>Animals have been killing other animals over resources and for recreation since before they emerged from the primordial soup.
And humans were pretty darn good at it long before FPS videogames and auto-loading rifles with box magazines. Just ask the adversaries of Ghengis Khan or Julius Caesar, for some good historical examples.
Again, the point here is about the killing perpetrated by an individual, not as part of a larger war machine. That’s why he gave the example of the lone rifleman. When many are required to manage a piece of artillery, they WILL aim to kill. Not so the rifleman, said Grossman prior to the conditionning of the pop-up humanoid silhouettes.