Oxytocin is a hormone found to be crucial in the formation of loving bonds between mothers and babies, and it's thought to just generally makes people feel more sympathetic and connected to each other. That's definitely true of rhesus monkeys.
These two rhesus monkeys are called Roku and Hex. They look like regular old rhesus monkeys, and indeed they were born completely normal and healthy. But they are, in fact, chimeras, each the result of splicing six different genomes together.
It's sometimes said that you should live life without regrets, but doing that means ignoring lots of information about how you could do things better. Even monkeys see the value in regret...at least after they throw rock instead of scissors.