What draws people to communal rituals has long been a topic of interest to sociologists and anthropologists.  What draws people to a communal ritual like walking on hot coals is a topic of interest for, well, everyone.   We all are fascinated by it but few want to do it, yet it has been going on (that we know of) since 1200 B.C.

Is it mind over matter?  The power of faith?   Flesh burns at a lot lower temperature than the 1,000 degrees F hot coals are at but, we know scientifically, there are different heat capacities in different materials.   So it might take 4.18 Joules to increase 1 cc of water by 1 degree C - and our feet are mostly water - but the coals actually have a much lower heat capacity than water, so the same amount of energy flowing from the hot coals reduces their temperature more (much more, it turns out) than the energy flowing to the feet will raise the foot's temperature.    In other words, it takes time for your feet to heat up to the same temperature as the coals, the same way you can stick your hand in a hot oven and not get burned by the hot air - on hot coals, you need to keep walking.    Praying may not hurt, but it is unlikely to help.

So we understand the physics of how it is possible, and man against nature is a common psychological motivator, but is there any reason a community would experience similar physiological effects to people walking on fire?

Ivana Konvalinka, doctoral student in the Center for Funktionelt Integrativ Neurovidenskab at Aarhus University in Denmark, discovered that the first rule of firewalking club is, you don't talk about firewalking club.

The researchers behind the study wanted to determine if there were biological underpinnings of communal rituals - yes, yes, evolutionary psychology but, just this once, we won't make fun of it because firewalking is cool - so they set out for a town in Spain known for these events.    Clearly, the locals thought it was a good idea at first and then had some suspicion because the mayor agreed and then told people not to be involved.

And all they wanted to do was put heart monitors on fire walkers.  Doesn't sound like much, right?  Well, Pam Belluck notes in her New York Times piece, you can't really measure oxytocin when someone is walking on hot coals.    So they did what they could do.

They did get people to agree, finally - 12 fire-walkers and 9 of their relatives plus 17 unrelated spectators.  The results:   Spectators did not care, as you would expect, but the heart rates of participants and their relatives did match before, during and after the walk.   "Synchronized arousal" they termed it.

Obviously the relatives and participants were having very different body experiences so, despite the small size of the study, the researchers believe it is worth considering that a 'collective ritual' may bring on this synchronized arousal and allow future research to quantify social behavior and physiological behavior in a community.

Now, take a look at famed skeptic (and Science 2.0 guest columnist) Michael Shermer as he gives it a shot:

Did your heart rate increase as much as his?   That would really be something.

Citation: Ivana Konvalinkaa, Dimitris Xygalatas, Joseph Bulbulia, Uffe Schjødt, Else-Marie Jegindø, Sebastian Wallot, Guy Van Orden, and Andreas Roepstorf, 'Synchronized arousal between performers and related spectators in a fire-walking ritual', PNAS May 2, 2011, Published online before print, doi: 10.1073/pnas.1016955108

Hat tip to Greg Critser