Mark Changizi is an evolutionary neurobiologist and director of human cognition at 2AI Labs. He is the author of The Brain from 25000 Feet, The Vision Revolution, and his newest book, Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man.”

Tom Stafford, co-author of the excellent book Mind Hacks, recently wrote a piece for the BBC about one of the most fundamental principles in the brain’s arsenal. This principle is so important that it ought to have a super-excitingly electrifying name; alas, it’s misleadingly boring. The principle is “adaptation,” or otherwise called “tuning out” or “getting used to it.” In an effort to help further communicate the sorts of powers adaptation gives us, it struck me to relate a remarkable “adaptation encounter” I recently had.

In 2011 I had the pleasure of visiting Japan for the first time. In addition to fascinating neuroscience, priceless culture, wonderful food, and world-class skiing, during my week there I had the mind-blowing experience of…turning Japanese.

You don’t think it’s possible for a white person to turn Japanese? Well, you can…perceptually. In fact, although it is I who had turned Japanese during my stay, from my first-person perspective it seemed as if every Japanese person had turned Caucasian!

As Twilight Zone-ish as this may sound, this sort of transformation is well-known and commonplace. What made it so intriguing for me was the extent to which I was, by virtue of my research proclivities, consciously aware of what usually flies below radar.

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By Keith Kloor, a freelance journalist whose stories have appeared in a range of publications, from Science to Smithsonian. Since 2004, he’s been an adjunct professor of journalism at New York University. You can find him on Twitter here.

Greens are often mocked as self-righteous, hybrid-driving, politically correct foodies these days (see this episode of South Park and this scene from Portlandia.) But it wasn’t that long ago—when Earth First and Earth Liberation were in the headlines—that greens were perceived as militant activists. They camped out in trees to stop clear-cutting and intercepted whaling ships and oil and gas rigs on the high seas.

In recent years, a new forceful brand of green activism has come back into vogue. One action (carried out with Monkey Wrenching flair) became a touchstone for the nascent climate movement.  In 2011, climate activists engaged in a multi-day civil disobedience event that has since turned a proposed oil pipeline into a rallying cause for American environmental groups.

This, combined with grassroots opposition to gas fracking, has energized the sagging global green movement. But though activist greens have frequently claimed to stand behind science, their recent actions, especially in regard to genetically modified organisms, or GMOs, say otherwise.

For instance, whether all the claims of fracking’s environmental contamination are true remains to be decided. (There are legitimate ecological and health issues-but also overstated ones. See this excellent Popular Mechanics deconstruction of all the “bold claims made about hydraulic fracturing.”) Meanwhile, an ancillary debate over natural gas and climate change has broken out, further inflaming an already combustible issue. Whatever the outcome, it’s likely that science will matter less than the politics, as often is the case in such debates.

That’s certainly the case when it comes to GMOs, which have been increasingly targeted by green-minded activists in Europe. The big story on this front of late has been the planned act of vandalism on the government-funded Rothamsted research station in the UK. Scientists there are testing an insect-resistant strain of genetically modified wheat that is objectionable to an anti-GMO group called Take the Flour Back. The attack on the experimental wheat plot is slated for May 27. The group explains that it intends destroy the plot because “this open air trial poses a real, serious and imminent contamination threat to the local environment and the UK wheat industry.”

Last month, Rothamsted scientists, in an open letter, asked to meet with the group to address its concerns. In the letter, they also pleaded with the activists not to carry out their avowed destructive act. Here is an excerpt:

We appeal to you as environmentalists. We agree that agriculture should seek to work “with nature rather than against it” (to quote from our website), and that motivation underlies our work. We have developed a variety of wheat which does not need to be sprayed with insecticides. Instead, we have intensified a way of getting the plant to repel aphids, using a natural process that has evolved in mint and many other plants–and simply adding this into the wheat genome to enable it to do the same thing.

So our GM wheat could, for future generations, substantially reduce the use of agricultural chemicals. Are you really against this? Or are you simply against it because it is “GMO” and you therefore think it is unnatural in some way?

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The American Psychiatric Association have just published the latest update of the draft DSM-5 psychiatric diagnosis manual, which is due to be completed in 2013. The changes have provoked much comment, criticism, and heated debate, and many have used the opportunity to attack psychiatric diagnosis and the perceived failure to find “biological tests” to replace descriptions of mental phenomena. But to understand the strengths and weaknesses of psychiatric diagnosis, it’s important to know where the challenges lie.

Think of classifying mental illness like classifying literature. For the purposes of research and for the purposes of helping people with their reading, I want to be able to say whether a book falls within a certain genre—perhaps supernatural horror, romantic fiction, or historical biography. The problem is similar because both mental disorder and literature are largely defined at the level of meaning, which inevitably involves our subjective perceptions. For example, there is no objective way of defining whether a book is a love story or whether a person has a low mood. This fact is used by some to suggest that the diagnosis of mental illness is just “made up” or “purely subjective,” but this is clearly rubbish. Although the experience is partly subjective, we can often agree on classifications.

Speaking the same language
How well people can agree on a classification is known as inter-rater reliability and to have a diagnosis accepted, you should ideally demonstrate that different people can use the same definition to classify different cases in the same way. In other words, we want to be sure that we’re all speaking the same language—when one doctor says a patient has “depression,” another should agree. To do this, it’s important to have definitions that are easy to interpret and apply, and that rely on widely recognised features.

To return to our literature example, it’s possible to define romantic fiction in different ways, but if I want to make sure that other people can use my definition it’s important to choose criteria that are clear, concise, and easily applicable. It’s easier to decide whether the book has “a romantic relationship between two of the main characters” than whether the book involves “an exploration of love, loss and the yearning of the heart.” Similarly, “low mood” is easier to detect than a “melancholic temperament.”

Accordingly, reliable diagnoses consist of a clear list of symptoms that are easy to define and evaluate. This can be evaluated with statistical test called Cohen’s kappa, and results from the DSM-5 field tests have just hit the headlines. Science journalist Ferris Jabr, writing on the latest results of field tests, reported that inter-rater reliability for the new “autism spectrum disorder” diagnosis was excellent, but for two of the most common diagnoses, generalized anxiety disorder and major depressive disorder, it was so bad as to make them unusable.

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Seth Shostak is Senior Astronomer at the SETI Institute in California, and the host of the weekly radio show and podcast “Big Picture Science.” 

Join Seth and 50 eminent scientists and sci-fi experts at SETIcon, to be held June 22-24 in Silicon Valley: www.seticon.org.

Battleship is not a film that Francois Truffaut would have made. Nor would any of those other namby-pamby European directors. Nope, this picture eschews that Continental obsession with small stories, set in quaint towns filled with pockmarked folk doing their banal things. Who cares?

No one, not when the fate of the Earth is in question. I’m proud to note that only the American film industry has the guts (not to mention the computer graphics horsepower) to fill the screen with a tale of ill-mannered aliens bent on incinerating the planet.

Consequently, Peter Berg’s film is pleasingly free of pretensions. It doesn’t waste your neural cycles exploring the uncharted labyrinths of the protagonists’ psyches, or anything overly Greek like that. It’s bad guys versus good guys, and the good guys win by being smarter, braver, and, in most cases, better looking.

The plot is exposed even before the main title settles in: NASA has found a planet that’s in the “Goldilocks” zone of its star—which is to say, it’s not too hot and not too cold for liquid water. It’s what astrobiologists would call a habitable world. Having found a possible home for E.T., the space agency beams up a signal that presumably informs any residents that Earthlings are friendly, and our planet is open for business.

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Eric Michael Johnson has a master’s degree in evolutionary anthropology focusing on great ape behavioral ecology. He is currently a doctoral student in the history of science at University of British Columbia looking at the interplay between evolutionary biology and politics. He blogs at The Primate Diaries at Scientific American, where this post originally appeared.

“Attachment (with respect to Martin Schoeller),” by Nathaniel Gold

My son will be 3 years old next month and is still breastfeeding. In other words, he is a typical primate. However, when I tell most people about this the reactions I receive run the gamut from mild confusion to serious discomfort. Their concerns are usually that extended breastfeeding could be stunting his independence and emotional development–the “Linus Blanket Syndrome” in the words of Michael Zollicoffer, a pediatrician at the Herman & Walter Samuelson Children’s Hospital at Sinai Hospital in Baltimore. Worse yet, they hint that it might even cause“destructive” psychosexual problems that he will be burdened with throughout his adult life. Could they be right? Was our choice “a prescription for psychological disaster” as Fox News psychiatrist Keith Ablow wrote in response to TIME magazine’s provocative cover article on attachment parenting? Just when is the natural age to stop breastfeeding?

One thing I’ve learned in my research on human evolution is that people are quick to assume that what they do is “natural” simply because they don’t know of other examples where things are done differently. The primate brain is a pattern recognition machine and is adapted to quickly identify regularities in our environment. But when we are presented with the same pattern over and over again it is easy to fall victim to what is known as confirmation bias, or coming to false conclusions because the evidence we use does not come from a broad enough sample. In order to avoid falling for this bias on the question of extended breastfeeding the best way forward would be to draw from the largest sample possible: the entire primate lineage.

In their classic paper, “Life History Variation in Primates” published in the premier scientific journal Evolution, the British zoologists Paul H. Harvey at Oxford and Tim Clutton-Brock at Cambridge published the most comprehensive data then available on the world’s primates. The variables they measured included everything from litter size and age at weaning to adult female body weight and length of the estrous cycle among 135 primate species (including humans). By analyzing the relationships between these variables, using a statistical approach known as a regression analysis, they identified striking patterns that held across primate taxa.

One especially strong correlation was that adult female body weight was closely tied to their offspring’s weaning age, so much so that knowing the first would allow you to predict the second with a 91% success rate. As a result, as anthropologist Katherine A. Dettwyler has shown in her book Breastfeeding: Biocultural Perspectives (co-edited with Patricia Stuart-Macadam), it can be calculated that a young primate’s weaning age in days is equal to 2.71 times their mother’s body weight in grams to the 0.56 power. This calculation predicts, given the range of female body sizes around the world from the !Kung-San of South Africa to the Arctic Inuit, that humans should have an average weaning age of between 2.8 and 3.7 years old.

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Sarah Zhang is Discover’s web intern. See her blogging here and here, and follow her on Twitter at @sarahzhang.

Delegates to Indiana’s constitutional convention worked under this tree in 1816.
It later succumbed to Dutch elm disease.

Unless you have a weakened immune system or a stubborn case of athlete’s foot, it’s unlikely you spend much time worrying about fungi. And you shouldn’t—fungal diseases are not generally a big problem for a healthy person; common ones like athlete’s foot are annoying but not serious. In terms of infections, it’s bacteria, parasites, and viruses that kill us.

But the rest of nature tells a different story. According to a recent review of fungal diseases in Nature, fungi are responsible for 72% of the local extinctions of animals and 64% among plants. White nose syndrome in bats and Dutch elm disease are two high-profile examples of extremely deadly fungal diseases gaining wider ranges through global trade. While each fungus itself is unique, many fungal pathogens share several special abilities that make them especially lethal.

Unlike viruses and most bacteria, fungi can survive—and survive for years—in dry or frigid environments outside of hosts. All they need to do is make spores: small, hardy reproductive structures containing all the necessary DNA to grow a new fungus. As spores, fungi can tough out adverse conditions and drift thousands of miles in the wind to find more livable settings. Aspergillus sydowii, for example, hitches a ride in dust storms from Africa to the Caribbean, where it infects coral reefs. They’re also ubiquitous in the air; there are one to ten spores in every breath you take. Wheat stem rust, a common fungus that causes $60 billion of crop damage a year, produces up to 10¹¹ spores per hectare, and they can travel 10,000 kilometers through the atmosphere to find new hosts. That’s only taking into account one of its five spore forms, which are produced at different times in its life cycle. For plants in general, fungi are the number one infectious threat, far above bacteria or viruses.

Many fungi are also generalists that use a scorched-earth strategy to parasitize a wide range of hosts. To invade host cells, viruses need to sneak their way in by fitting into specific proteins like a key in a lock. Because viruses need to have this precision, it’s hard for them to jump from one species to another one with a different set of proteins, and it’s a big deal when it does happen. Fungi, on the hand, don’t need to enter cells; like the mold that eats your bread, it squirts its digestives juices and rots everything in sight. While viruses nimbly pick your locks, fungi are like a bomb that will blow up your door—or anyone else’s.

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Neuroskeptic is a neuroscientist who takes a skeptical look at his own field and beyond at the Neuroskeptic blog. 

Why do we sleep? We spend a third of our lives doing so, and all known animals with a nervous system either sleep, or show some kind of related behaviour. But scientists still don’t know what the point of it is.

There are plenty of theories. Some researchers argue that sleep has no specific function, but rather serves as evolution’s way of keeping us inactive, to save energy and keep us safely tucked away at those times of day when there’s not much point being awake. On this view, sleep is like hibernation in bears, or even autumn leaf fall in trees.

But others argue that sleep has a restorative function—something about animal biology means that we need sleep to survive. This seems like common sense. Going without sleep feels bad, after all, and prolonged sleep deprivation is used as a form of torture. We also know that in severe cases it can lead to mental disturbances, hallucinations and, in some laboratory animals, eventually death.

Waking up after a good night’s sleep, you feel restored, and many studies have shown the benefits of sleep for learning, memory, and cognition. Yet if sleep is beneficial, what is the mechanism?

Recently, some neuroscientists have proposed that the function of sleep is to reorganize connections and “prune” synapses—the connections between brain cells. Last year, one group of researchers, led by Gordon Wang of Stanford University reviewed the evidence for this idea in a paper called Synaptic plasticity in sleep: learning, homeostasis and disease.

This illustration, taken from their paper, shows the basic idea:

While we’re awake, your brain is forming memories. Memory formation involves a process called long-term potentiation (LTP), which is essentially the strengthening of synaptic connections between nerve cells. We also know that learning can actually cause neurons to sprout entirely new synapses.

Yet this poses a problem for the brain. If LTP and synapse formation is constantly strengthening our synapses, and we are learning all our lives, might the synapses eventually reach a limit? Couldn’t they “max out,” so that they could never get any stronger?

Worse, most of the synapses that strengthen during memory are based on glutamate. Glutamate is dangerous. It’s the most common neurotransmitter in the brain, and it’s also a popular flavouring: “MSG”, monosodium glutamate. But in the brain, too much of it is toxic.

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Science journalist Robin Marantz Henig is a contributing writer at The New York Times Magazine. Her next book, co-authored with her daughter Samantha Henig, is called Twentysomething: Why Do Young Adults Seem Stuck? and will be out in November.

Is regret something you accumulate in your life, piling it up as you remember an ever-increasing number of things that really could have gone better? If so, you’d think that young people would have fewer regrets than older ones, since they haven’t lived as long and haven’t missed as many chances—and if they have missed a chance at some adventure or relationship, they’re more likely to think that the chance will come around again.

But a recent study by Stefanie Brassen and her colleagues at University Medical Center Hamburg-Eppendorf in Germany suggests that young people feel more regret than old people, largely because the older people seem to be quashing those nasty feelings before the feelings overtake them. Indeed, they found that the only 60-somethings who experienced regret at the same level as 20-somethings were those who were depressed.

I think it’s worth considering, though, whether the German investigators really were tapping into regret at all, or a different aspect of youth psychology.

Brassen and her colleagues simulated regret by having her subjects play a Let’s Make a Deal-type computer game in which they opened a succession of boxes to earn cash. They could keep opening boxes and keep accumulating cash as long as they stopped before they opened the box containing a pop-out devil. If they got to the devil, the game was over and they had to give back everything they’d earned in that round.

The researchers were less interested in how many boxes the subjects opened than in how they felt about the chances they missed. After the round was over, the investigators revealed the contents of the unopened boxes. The more boxes the subjects could have opened before getting to the devil, the more regret they were expected to feel, since they could have earned even more money if they’d been just a little more daring.

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As these plots of bacterial diversity in two subjects over a period of 16 weeks show,
microbiomes vary widely among women and change radically over time.

When John Mayer sang “Your Body is a Wonderland,” he probably wasn’t talking about the trillions of microbes that live all over your skin and inside every orifice you have to offer—but it does pretty much describe things. In the last decade or so, scientists have confirmed that we’re just as much an ecosystem as a rainforest is: full of ecological niches inhabited by countless bacteria, many of which have been evolving with us for millions of years. Our tiny passengers aren’t passive, either. Studies in mice and some in humans have linked these microbial populations, or microbiomes, to the host’s digestion, gut health, behavior, and even mood. A healthy microbiome keeps the host’s systems in good working order and prevents invasion by microbes that mean us harm.

But what is a healthy microbiome, exactly? That’s an important question, since diagnosing and treating illnesses related to microbiome imbalance requires some definition of normal. In the first few studies to try to address this question, scientists have found that there are some patterns: one study suggested that there could be three gut microbiome “types,” similar to blood types. Since proposed treatments for microbiome problems include “transfusions” of bacteria from a healthy microbiome (including “fecal transplants“), this is an attractive analogy. But a new study on the human vaginal microbiome suggests that the real story might be much more complicated.

Studies exploring a healthy micobiome often look at a single sample from each person. But it turns out if you sample someone regularly, at least in the case of the vagina, you can watch the entire microbiome change radically—to the point of becoming unrecognizable—in a matter of days.

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Razib Khan’s degrees are in biochemistry and biology. He has blogged about genetics since 2002 (see his Discover Blog, Gene Expression), previously worked in software development, is an Unz Foundation Junior Fellow and lives in the western US. He loves habaneros.

…At some future period, not very distant as measured by centuries, the civilized races of man will almost certainly exterminate and replace throughout the world the savage races. At the same time the anthropomorphous apes, as Prof. Schaaffhause has remarked, will no doubt be exterminated. The break will then be rendered wider, for it will intervene between man in a more civilized state, as we may hope, than the Caucasian and some ape as low as a baboon, instead of as at present between the negro or Australian and the gorilla.

- The descent of man, and selection in relation to sex, Volume 1 – by Charles Darwin

The above quote is not to vilify Charles Darwin. On the contrary, I believe Darwin was a scientific hero whose work is the foundation of modern biology. Nevertheless, he was a man of his age. Despite the fact that Darwin was a political liberal from a family of liberals, with pristine credentials in progressive social movements of his day, such as the anti-slavery campaigns, it is clear that he had Victorian biases nonetheless; some of the passages in The descent of man clearly come from a fortunately bygone era, when white scholars and adventurers cataloged and surveyed the unexplored corners of our world, and created taxonomies of the “lower races” as if they were just part of the local fauna. The reality is that Charles Darwin’s age was fundamentally one of white supremacy. In the year 1900, one out of three human beings alive was of European extraction. In the four centuries since Christopher Columbus, Europe and its Diaspora had entered into massive demographic expansion—which many Victorians saw as survival of the fittest. Progressives of the late 19th and early 20th century, such as H. G. Wells, foresaw a future where the “higher races” would naturally marginalize those peoples who were lesser participants in civilization. Such was taken as the judgment of nature.

How 100 years do change things. And yet just as Darwin could not help but reflect the presuppositions of his era, so we in our day can not help but channel the zeitgeist. Like Charles Darwin, today’s scholars have concluded that humans are fundamentally an African species. But unlike Darwin they conclude from this that there is a biological, essential unity of humankind, such that talk of “civilized” and “savage” is rendered moot and irrelevant. We do look through the mirror of our ages darkly, seeing startlingly different insights from the same shadows of reality. Whereas racist assumptions and beliefs were supported by interpretations of science of the 19th century, today we attempt to harness science in the opposing direction.

The topic of human variation, and more plainly, race, is fraught. The past century has seen a wild swing from the widespread acceptance of the idea that human races are real, with big, important differences, to the opposite position: that race is fundamentally an illusion, a social construction of the human mind. But both of these arguments are mistaken. The established modern consensus about the equality of people, irrespective of race, is morally and ethically justified. But these beliefs we hold to be true do not derive from the natural science, which doesn’t present a clear moral lesson.

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