[nurettin]

>> On the one hand, you have thousands of years of anecodata compiled by billions of people

That or you have fourty years of urban legends and billions who believe it without checking any facts.

[knowThySelfx]

Actually, much more than 40 years. Many of the practitioners acquire their practice and knowledge from their parents. And the parents from their own parents. I am talking from what I've seen and experienced first hand. They also learn Vaastu and Astrology among other things. In addition, Ayurvedic Colleges are also there supported by the Indian Govt.