system
A chat on subreddit /r/NoStupidQuestions
human
I rather disagree with the statement that violent men are selected for. Consider the men who were not on the battlefield such as farmers or blacksmiths who are required to support an army. In a conflict they were less likely to be killed because their skills were valued. Those that survived were more likely to reproduce than the men who died at war. Hence why the last name "Smith" is so common
gpt
It's also why Kamikaze is a very rare last name.