The natural world seems intent on synchronizing . Schools of fish, flocks of birds, herds of wildebeest, and swarms of fireflies all effortlessly coordinate their actions with one another. A recent study published by Scott Wiltermuth and Chip Heath of Stanford University in the journal Psychological Science, suggests that humans are no different. In fact, our ability to synchronize might be one of the most important developments in our evolution as a social species, a skill we need to successfully choreograph our dance moves at parties--and also, perhaps, to live together in stable, cooperative societies .

Examples of the power of human synchrony abound--from the awe-inspiring opening ceremony of the 2008 Summer Olympics to the fear-inspiring Nazi military march, to the ridiculous communal dances in which we find ourselves at weddings. Who hasn’t bad-mouthed the chicken dance in the buffet line and then been drawn in by that insufferable staccato? Like a Siren, the allure of synchrony pulls you into the group.

If people told you that they wanted to have a perfectly good leg amputated, or that they have three arms, when they clearly do not, you would probably think that they are mentally disturbed. Psychiatrists, too, long considered such conditions to be psychological in origin. Voluntary amputation, for example, was regarded as a fetish, perhaps arising because an amputee's stump resembles a phallus, whereas imaginary extra limbs were likely to be dismissed as the products of delusions or hallucinations.

These bizarre conditions--named body integrity and identity disorder (BIID) and supernumerary phantom limb, respectively--are now believed to have a neurological basis, and a growing body of literature suggests that such body awareness disorders occur as a result of abnormal activity in the right superior parietal lobule (SPL). This brain region integrates different types of sensory information and processes it further to generate an internal model of the body. Two forthcoming studies provide strong evidence that the gross distortions of body image experienced in both conditions do indeed occur as a result of SPL dysfunction.

In 1998 Judith Rich Harris , an independent researcher and textbook author, published The Nurture Assumption: Why Children Turn Out The Way They Do . The book provocatively argued that parents matter much less, at least when it comes to determining the behavior of their children, than is typically assumed. Instead, Harris argued that a child’s peer group is far more important. The Nurture Assumption has recently been reissued in an expanded and revised form. Mind Matters editor Jonah Lehrer chats with Harris about her critics, the evolution of her ideas and why teachers can be more important than parents.

LEHRER: Freud famously blamed the problems of the child on the parents. (He was especially hard on mothers.) In The Nurture Assumption, an influential work that was published 10 years ago, you argued that parents are mostly innocent and that peers play a much more influential role. What led you to write the book?

Alas! Poor Yorick. I knew him well. A fellow of infinite jest, of most excellent fancy; he hath borne me on his back a thousand times; and now, how abhorred in my afterimage he is!

Well… that’s what Hamlet would have said, had he been holding the vintage Pear’s Soap advertisement bearing Yorick’s skull in the accompanying slide, rather than a dug up and rotting Danish cranium. In this antique illusion, you can stare at the X in Yorick’s left eye socket for about 10 to  30 seconds, then look away at a flat surface such as a piece of paper, wall, ceiling or sky, and you will see Yorick’s afterimage as a ghostly apparition.

A magician tosses a ball into the air once, twice, three times. Suddenly, the ball vanishes in mid-flight. What happened?

Don’t worry, the laws of physics haven’t been broken. Magicians do not have supernatural powers; rather, they are masters of exploiting nuances of human perception, attention, and awareness. In light of this, a recent Nature Reviews Neuroscience paper , coauthored by a combination of neuroscientists (Stephen L. Macknik, Susana Martinez-Conde, both at the Barrows Neurological Institute) and magicians (Mac King, James Randi, Apollo Robbins, Teller, John Thompson), describes various ways magicians manipulate our perceptions , and proposes that these methods should inform and aid the neuroscientific study of attention and awareness. [More]

When people are asked to list their favorite metaphor , they typically cite great works of poetry, literature or oratory. Indeed, many metaphors are born from creative insight--Romeo likening Juliet to the rising sun or poet Robert Burns comparing his love to a red rose. [More]

Hara hatchi bu , the Okinawan people’s habit of eating only till they are 80 percent full, is thought to be one of the secrets of their extraordinary health and longevity. In addition to one of the highest percentages of people in the world who live past 100, Okinawans appear to be less prone to heart disease, diabetes and obesity.

Indeed, ever since it was discovered in the 1930s that laboratory rats fed a caloric-restricted (CR) diet lived almost twice as long as their well fed counterparts, scientists have pursued caloric restriction research in the hopes of finding novel strategies for extending human life and preventing disease. Given the growing older population at risk for memory problems and the rising rates of obesity, the role of diet in maintaining peak brain performance has taken on added importance.

Why do people do good things? Is kindness hard-wired into the brain, or does this tendency arise via experience? Or is goodness some combination of nature and nurture? [More]

Giraffes’ long necks are perfectly suited to harvesting tender leaves beyond the reach of other herbivores. Pondering the genesis of this phenomenon, two giants of modern biology, Jean-Baptiste Lamarck and Charles Darwin, arrived at remarkably different hypotheses. Lamarck believed that constant stretching of the neck somehow stimulated its growth. The giraffe would then pass along this new trait to its offspring. In effect, this newer, longer neck was a direct result of a giraffe’s interaction with its environment. By contrast, Darwin’s theory posited that traits evolve as part of a random, gradual process. The giraffes that happened to have been born with longer necks thanks to a random genetic mutation were better fed and thus healthier than their shorter-necked counterparts, making them more likely to live long enough to breed and pass on this trait. Because this mutation conferred a specific advantage to long-necked giraffes that aided their survival, the trait was preserved in future generations. [More]

Matthew Lieberman is associate professor of social neuroscience at the University of California, Los Angeles.  In recent weeks, he’s also rebutted the claims of a recent paper, “Voodoo Correlations in Social Neuroscience,” which explored the high correlations between measures of personality or emotionality in the individual--such as the experience of fear, or the willingness to trust another person--with the activity of certain brain areas as observed in an fMRI machine. Mind Matters editor Jonah Lehrer chats with Lieberman about why most fMRI correlations aren’t false, the “reward” of intense grief and why accepting unfair offers seems to activate brain areas involved with self-control.

LEHRER: Your field of research has come under fire in a recent paper titled "Voodoo Correlations in Social Neuroscience."   What's the authors' argument and have they identified a significant problem in this field?