Oxytocin synchronizes physiological processes and enhances bonding, especially with touch.

“Meaning the oxytocin response is so powerful that it doesn't even require that both individuals experienced this user inflection and oxytocin, and that's because one person's physiology is influencing the other, and oxytocin is this kind of bridging signal that occurs in both nervous systems, synchronizes things like heartbeat, obviously it's associated with touch. And so if people are touching or people are engaging in the sorts of behaviors that I mentioned earlier, that can increase oxytocin further, that's going to further increase the depth of the bond.”