Have we found Althruism?
... A split that's worse than 70/30 tends to get rejected. People will give up $30 of free money in order to punish someone they believe is treating them unfairly....We've discovered altruism in humans, not economic rationality...
Er, NO!
What you've discovered is a hatred of UNFAIRNESS.
The experiment simply presents an unfair division to a subject, and asks them if they want to accept it. Unsurprisingly, people say no when the advantage to them is small, but can be persuaded if the advantage is high enough.
If, for instance I was offered £1m under similar circumstances, I wouldn't turn it down, even if the offerer was going to get £99m. I would rationalise my unhappiness away.
You see the same sort of thing going on when dictators make people into concentration camp guards and mass murders by threatening them with death if they don't agree. Effectively, they are being offered their life as part of an unfair bargain...
Biting the hand that feeds IT
