I don't think it's about undoing the damage, it's about evening the damage. If you punch me and I feel hurt two days later, then I may still want to punch back. If I have healed physically and emotionally, forgiven you completely, do you think I'm as likely to punch you then?
It's easy to imagine that it's personally for spite, but evolutionarily for deterrence (i.e., spite is an evolutionarily effective way to encode deterrence).
[0]: https://aeon.co/ideas/punishment-isnt-about-the-common-good-...
If it’s a random stranger, someone you won’t encounter again, or you live in a society where violence is very rare, then it’s probably a moot point.
We evolved in small tribes where everyone knew everyone, and just about everything that happened would quickly be known by the whole group. Combine that with scarcity and a higher propensity for violence, and being seen as an easy target would be something to avoid at all costs.
Maybe you could argue that by crying, the older child was getting revenge on the younger because he knew his parents would come to scold him. Or maybe the kid just wanted comfort because he lost something he cared about. It was hard for me to know whether his intention was to receive comfort and attention or to have his parents shame his brother, maybe both?
> Combine that with scarcity and a higher propensity for violence
I guess I don't see this as a given as much as it seems you do. I suppose I think people act violently out of pain, most of us just lashing out at each other because we think they hurt us first, more cooperative by nature than competitive, but maybe I'm describing your views inaccurately.
Granted the initial 3 sequel books were large tomes about the corresponding guilt, repentance, and consequences stemming from that initial idea.