It's funny that the other one doesn't share his grape, they did a similar experiment with bonobos, our closest relatives: one of them could reach good food, the other couldn't. The one that could reach it opened the cage door between their two cages so they both could eat.
TLDR: Bonobos seem to know that sharing is caring.
Luckily, humans don't share that trait, which is why socialism can work. We're all so altruistic that we don't mind working at more demanding jobs, or ones that require difficult and specialized training, for the same pay as easy ones because everyone will have his/her/its/their needs met. Well, what the State defines as "needs" at least.
TLDR: Bonobos seem to know that sharing is caring.