Test subjects taking part in an 8-week program of mindfulness meditation showed results that astonished even the most experienced neuroscientists at Harvard University.  The study was led by a Harvard-affiliated team of researchers based at Massachusetts General Hospital, and the team’s MRI scans documented for the very first time in medical history how meditation produced massive changes inside the brain’s gray matter.  “Although the practice of meditation is associated with a sense of peacefulness and physical relaxation, practitioners have long claimed that meditation also provides cognitive and psychological benefits that persist throughout the day,” says study senior author Sara Lazar of the MGH Psychiatric Neuroimaging Research Program and a Harvard Medical School instructor in psychology. “This study demonstrates that changes in brain structure may underlie some of these reported improvements and that people are not just feeling better because they are spending time relaxing.”

Sue McGreevey of MGH writes: “Previous studies from Lazar’s group and others found structural differences between the brains of experienced meditation practitioners and individuals with no history of meditation, observing thickening of the cerebral cortex in areas associated with attention and emotional integration. But those investigations could not document that those differences were actually produced by meditation.”  Until now, that is.  The participants spent an average of 27 minutes per day practicing mindfulness exercises, and this is all it took to stimulate a major increase in gray matter density in the hippocampus, the part of the brain associated with self-awareness, compassion, and introspection.  McGreevey adds: “Participant-reported reductions in stress also were correlated with decreased gray-matter density in the amygdala, which is known to play an important role in anxiety and stress. None of these changes were seen in the control group, indicating that they had not resulted merely from the passage of time.”

For many years I had heard stories about the "Hundredth Monkey phenomenon" and was fascinated with the possibility that there might be some sort of collective consciousness that we could tap into to decrease crime, eliminate wars, and generally unite as a single species. In the 1992 presidential election, in fact, one candidate—Dr. John Hagelin from the Natural Law Party—claimed that if elected he would implement a plan that would solve the problems of our inner cities: meditation. Hagelin and others (especially proponents of Transcendental Meditation, or TM) believe that thought can somehow be transferred between people, especially people in a meditative state; if enough people meditate at the same time, some sort of critical mass will be reached, thereby inducing significant planetary change. The Hundredth Monkey phenomenon is commonly cited as empirical proof of this astonishing theory. In the 1950s, so the story goes, Japanese scientists gave monkeys on Koshima Island potatoes. One day one of the monkeys learned to wash the potatoes and then taught the skill to others. When about one hundred monkeys had learned the skill—the so-called critical mass —suddenly all the monkeys knew it, even those on other islands hundreds of miles away. Books about the phenomenon have spread this theory widely in New Age circles. Lyall Watson's Lifetide (1979) and Ken Keyes's The Hundredth Monkey (1982), for example, have been through multiple printings and sold millions of copies; Elda Hartley even made a film called The Hundredth Monkey.

As an exercise in skepticism, start by asking whether events really happened as reported. They did not. In 1952, primatologists began providing Japanese macaques with sweet potatoes to keep the

monkeys from raiding local farms. One monkey did learn to wash dirt off the sweet potatoes in a stream or the ocean, and other monkeys did learn to imitate the behavior. Now let's examine Watson's book more carefully. He admits that "one has to gather the rest of the story from personal anecdotes and bits of folklore among primate researchers, because most of them are still not quite sure what happened. So I am forced to improvise the details." Watson then speculates that "an unspecified number of monkeys on Koshima were washing sweet potatoes in the sea"—hardly the level of precision one expects. He then makes this statement: "Let us say, for argument's sake, that the number was ninety-nine and that at 11:00 A.M. on a Tuesday, one further convert was added to the fold in the usual way. But the addition of the hundredth monkey apparently carried the number across some sort of threshold, pushing it through a kind of critical mass." At this point, says Watson, the habit "seems to have jumped natural barriers and to have appeared spontaneously on other islands" (1979, pp. 2-8).

Let's stop right there. Scientists do not "improvise" details or make wild guesses from "anecdotes" and "bits of folklore." In fact, some scientists did record exactly what happened (for example, Baldwin et al. 1980; Imanishi 1983; Kawai 1962). The research began with a troop of twenty monkeys in 1952, and every monkey on the island was carefully observed. By 1962, the troop had increased to fiftynine monkeys and exactly thirty-six of the fifty-nine monkeys were washing their sweet potatoes. The "sudden" acquisition of the behavior actually took ten years, and the "hundred monkeys" were actually only thirty-six in 1962. Furthermore, we can speculate endlessly about what the monkeys knew, but the fact remains that not all of the monkeys in the troop were exhibiting the washing behavior. The thirtysix monkeys were not a critical mass even at home. And while there are some reports of similar behavior on other islands, the observations were made between 1953 and 1967. It was not sudden, nor was it necessarily connected to Koshima. The monkeys on other islands could have discovered this simple skill themselves, for example, or inhabitants on other islands might have taught them. In any case, not only is there no evidence to support this extraordinary claim, there is not even a real phenomenon to explain.