From a historical perspective it is ironic that tickling in the modern era is considered to be a way to bond for parents and their children because a few centuries back tickling was a form of punishment.

Thanks to evolution laughter became a way for people to enjoy each other's company without any danger or injuries.

Laughter is a form of social bonding because it is contagious and allows us to show that we are non-threatening.

We laugh when we see or hear something funny. We laugh to show that we are being silly.