By focusing on a specific object, such as a blazing fire, people are likely to relax and achieve a meditative state. That’s why sitting around a campfire is so special and also beneficial to your health. It allows you to forget all your troubles and focus on the present. The warmth, combined with the hypnotic effect of the flames, only adds to this.
There’s also the ritual involved in build a fire that makes it so much more personal than the instant heat you get at the flick of a switch. It takes time, not only to gather your materials and to get a fire going, but also for food to cook on it. It’s during these moments that people chat to each other and form a bond.
It’s also the fact that you’re out amongst nature and in the open air that helps to release people of their inhibitions. It would be hard to imagine people telling stories and singing songs gathered around a radiator. A campfire puts a living heart into any gathering.