Is There a Moment in Evolution That You Could Learn, Discover?

Laughter is just such a human part of the way we live, isn't it? There's so little scientific study of it. People will go out of their ways to try and be in places or with people where they know that they will laugh. If there was something that happened in the brain that not very long later, and not all that differently in terms of physical properties gives us modern humans, I would love to know what that could have been.