Hi Grout,
I can understand your reasoning behind this statement you made:
As for magnetic fields etc., well, if humans were that sensitive to them then you'd see people getting all disoriented when they go through MRI machines. Do you have any idea how weak Earth's magnetic field is compared to even a toy magnet at close range, let alone an MRI machine? It makes no sense whatsoever to attribute dowsing to magnetic sensitivity in humans. There's no evidence for such sensitivity in other circumstances where it should be seen.
...but I regret to inform you that it is not correct. There is a well developed body of knowledge that exists on how human's are extremely sensitive to magnetic fields and electromagnetic waves. I could spend a few hours just listing all the studies that have been done.
I have never tried dowsing. When I studied geophysics in college, everything I read at the time suggested it was bunk. I've worked though with geologists who claimed there was something to it but I've never read any papers about controlled studies. So, my honest perspective right now is that I don't know because I haven't investigated the subject enough to say if it works or not.
I do know there are several unusual things that happen in real life. A lot of scientists run screaming in the opposite direction when something weird walks their way but others look at it as an opportunity to learn something new about the world. I like mysteries and being on the edge of science myself but I'm on the tails of the Bell-shaped curve!
Oh, and your mention of Clever Hans was cool...the horse that could do math! Right on there.
Adios,
Skipper
"The fault, dear Brutus, is not in our stars, but in ourselves that we are underlings." - William Shakespeare