The Science of Yoga

sense of wariness. Long ago, while working at the University of Wisconsin on a study of respiratory physiology, I came across a flat contradiction to one of modern yoga’s central tenets—that fast breathing floods the body and brain with revitalizing oxygen. In contrast, a textbook I was reading at the time said the pace of human respiration “can drop to one-half or rise to over one hundred times normal without appreciably influencing the amount of blood oxygenated.” I see now that, in 1975, I underlined that passage quite heavily.
    Unfortunately, my survey lived up to my low expectations. Some books and authors shone brightly. (See Further Reading for a list.) But on the whole, I found the literature dull with dreaminess, assertions with no references, and a surprising number of obvious untruths. I wanted tips for tracking down good science but instead got a muddle. The writing, old and new, turned out to run toward the curiously dogmatic and, at best, to contain only a smattering of science. Much of it was similar to what Richard Feynman, a founder of modern physics, disparaged as cargo-cult science—that is, material that appears scientific but lacks factual integrity.
    By contrast, my plunge into the scientific literature left me heartened. Federal officials at the National Institutes of Health in Bethesda, Maryland, run a wonderful electronic library of global medical reports known as PubMed, short for Public Medicine. It showed that scientists had written nearly one thousand papers related to yoga—the number rising in the early 1970s and soaring in recent years, with reports added every few days. The studies ranged from the flaky and superficial to the probing and rigorous. The authors included researchers at Princeton and Duke, Harvard and Columbia. Moreover,the field had gone global. Scientists in Sweden and Hong Kong were publishing serious papers.
    But the closer I looked, the more I judged this body of information to be rather limited. Some general topics had been covered fairly well—for instance, how yoga can relax and heal. But many others were ignored, and much of the published science turned out to be superficial. For instance, studies for the approval of a new drug can require the participation of hundreds or even thousands of human subjects, the large numbers increasing the reliability of the findings. In contrast, many yoga investigations had fewer than a dozen participants. Some featured just one individual.
    The superficiality turned out to have fairly obvious roots. Research on yoga was often a hobby or a sideline. It had no big corporate sponsors (there being no hope of discoveries that could lead to expensive pills or medical devices) and relatively little financial support from governments. Federal centers tend to specialize in advanced kinds of esoteric research as well as pressing issues of public health, with their investigations typically carried out at institutes and universities. In short, modern science seemed to care little.
    The exception turned out to be areas where yoga intersected other disciplines or made bold claims strongly at odds with the conventional wisdom. Such crossroads proved to be scientifically rich. For instance, scientists interested in sports medicine and exercise physiology had lavished attention on yoga’s fitness claims. So, too, physicians had zeroed in on yoga’s reputation for safety.
    The limitations of the current literature sent me casting a wide net, and I immediately made a big catch. It was a very old book— A Treatise on the Yoga Philosophy —written by a young Indian doctor and published in 1851 in Benares (now known as Varanasi), the ancient city on the Ganges that marks the spiritual heart of Hinduism. It came to my attention because a few Western scholars had referred to it in passing.
    I got lucky and found that Google Books had recently scanned Harvard’s copy into its electronic archive, so I was able to download the whole thing in a flash. Its language was archaic. But the author had addressed the science of yoga with great skill, illuminating an important aspect of respiratory physiology that many authorities still get wrong today.
    The book surprised me because I had been told that Indian research on yoga—though pioneering—wastypically of poor quality. But I kept finding gems. A curious scientist, often working in India or born in India and doing research abroad, would address some riddle of yoga and make important finds.