Laughter is an indication — to yourself and others — that you don't need to be in fight-or-flight mode, that you are not in combat. Research indicates that you don't actually have to be funny: just indicate a mindset where you might enjoy laughing with the human beings you are talking with.
Start here: The Second Most Powerful Tool in Conflict Laughing matters is a great introduction by Amanda Ripley. Especially note how easy it can be: you don't have to tell a funny joke. If you are listening to people, and seem like might enjoy a laugh with them even you don't have a joke up your sleeve — that's a conversation with people you want on your team, seeking to learn about the world together, not a conflict.
From the business world: Make ’Em Laugh: How Humor Can Be the Secret Weapon in Your Communication. Matt Abrahams interviews Stanford GSB Professor Jennifer Aaker and Lecturer Naomi Bagdonas.
And from the academic world: A Laughing matter? Confronting climate change through humor by Maxwell Boykoff and Beth Osnes.