If you were slighted or insulted in front of people (especially the opposite sex) the urge to hit is very strong.
But *smart* hominids don't hit with their fist; they hit with a handy stick or rock. (1) It works far better, and your opponent isn't getting up for a second round, (2) hitting without a weapon is more likely to cause injury to the hitter, both from the punch and from the retaliation, (3) this identifies you as a hominid other monkey-men should respect, and monkey-ladies should consider surfing the gene pool with.
People tend to take things like punching as "natural", ignoring the *cultural* training that teaches us to go for the fist first. Punching is *not* a natural behavior. Grabbing, taking the ground and biting *are*, which comes as a surprise to a lot of martial artists in their first street fight. Hand-to-hand combat systems are just about *all* adjunct training methods fo military weapons use. That's why so much of the basics of empty-handed combat make so little sense. They make lots of sense when you graduate to the sword or the spear. A punch is perhaps a useful backup move when you've lost your weapon, or as a surprise trick, but not much more. The few martial arts that truly come from a brawling background emphasize grappling.