Why are we so nice? ...because generosity wins.

Here is a further entry in Nature's "Being Human" series, in which Martin Nowak points out that mathematical models predict, and experiments confirm, that generosity is an essential feature of winning strategies in games that explore human interactions. 'Prosocial behaviour' has evolved within a framework of direct or indirect reciprocity, and the latter may have provided selection pressure for social intelligence and language. A few excerpts:

Only if certain mechanisms are involved can natural selection favour individuals who reduce their own fitness to increase that of a competitor. One such mechanism is direct reciprocity: my strategy depends on what you have done to me. Another is indirect reciprocity: my strategy depends on what you have done to me and on what you have done to others.

In both, mathematical analysis shows that winning strategies tend to be generous, hopeful and forgiving. Generous here means not seeking to get more than one's opponent; hopeful means cooperating in the first move or in the absence of information; and forgiving means attempting to re-establish cooperation after an accidental defection. These three traits are related. If I am generous, it is easier for me to forgive, and also to be hopeful and take the risk of cooperating with newcomers.

Experiments have confirmed the success of generosity. A typical set-up involves students and computer screens. The computer pairs random individuals. One person, the donor, is asked if she wishes to transfer some money to the recipient. She is informed about the recipient's decisions in previous rounds with other players. The experiment shows that people base their decision on what the recipient has done before. Generous people are more likely to receive donations.

Similar reputation-based systems operate in e-commerce. When buying a camera online, you might consider both the price and the seller's reputation. Consumers are willing to pay higher prices if the seller is thought to be reliable. Successful websites are those with good reputations.

So why aren't humans always 'generous, hopeful and forgiving'? Part of the explanation may be that cooperation is never a stable state. Mathematical studies show that it is constantly challenged by defection. In a society of defectors where no-one helps, a cluster of cooperating individuals can emerge if, by chance, a few people start playing a direct reciprocity strategy called tit-for-tat: I do whatever you have done to me. Tit-for-tat can't persist for long because its appetite for revenge is self-destructive. It is soon replaced by 'generous tit-for-tat'. Here, I cooperate whenever you have cooperated, but sometimes even when you have defected. In other words, I am forgiving. For a while, cooperation thrives. But in a generous tit-for-tat population, the emergence of unconditional cooperators eventually invites the invasion of defectors. This leads to cycles of cooperation and defection — which could account, at least in part, for the mix of cooperators and defectors that persists in human societies.

Mathematical models allow a precise investigation of fundamental aspects of human behaviour. The games described here occur in every society. Ancestral humans spent most of their time in small groups where interactions were repeated. The same is true for most dealings in modern life: repeat encounters are always possible and reputation is typically at stake. The evolution of prosocial behaviour cannot be understood outside the framework of direct or indirect reciprocity. Indeed, I believe that games of indirect reciprocity have provided the crucial selection pressures for social intelligence and language.

In such games, social intelligence is needed to monitor and interpret the interactions of others. We follow with great interest what our fellow creatures do to us and to others. When deciding how to act, we take into account — often subconsciously — the possible consequences for our own reputation. Moreover, our own observations are often not enough; we want to learn from the experiences of others. Spreading the rumours of indirect reciprocity requires language. As my colleague David Haig once remarked "for direct reciprocity you need a face, for indirect reciprocity you need a name".

Wheel of life.

I recently came across this interesting graphic demonstration of the Buddha's wheel of life, narrated by Robert Thurman.

How a cognition enhancing drug works.

Minzenberg et. al. find that brain images of humans treated with a cognitive enhancing drug show increased task-oriented activity in a brainstem nucleus and confirm that this region controls cognition. Their abstract:

Models of cognitive control posit a key modulatory role for the pontine locus coeruleus–norepinephrine (LC-NE) system. In nonhuman primates, phasic LC-NE activity confers adaptive adjustments in cortical gain in task-relevant brain networks, and in performance, on a trial-by-trial basis. This model has remained untested in humans. We used the pharmacological agent modafinil to promote low-tonic/high-phasic LC-NE activity in healthy humans performing a cognitive control task during event-related functional magnetic resonance imaging (fMRI). Modafanil administration was associated with decreased task-independent, tonic LC activity, increased task-related LC and prefrontal cortex (PFC) activity, and enhanced LC-PFC functional connectivity. These results confirm in humans the role of the LC-NE system in PFC function and cognitive control and suggest a mechanism for therapeutic action of procognitive noradrenergic agents.

Advocacy of cognition enhancing drugs.

Stimulants such as methyl-phenidate (Ritalin) and modafinil (Provigil), familiar as treatments for attention deficit hyperactivity disorder and narcolepsy respectively, are increasingly used as 'smart drugs' by students and more widely as a boost to intellectual creativity. Should society recognize the demand for cognitive enhancement? The trend has been resisted by some on the grounds of safety, 'medicalization' and social inequality. Urging responsible use of cognitive-enhancing drugs by the healthy, Greely et al., in an open access article, think that society must respond to the growing demand for cognitive enhancement. A few clips from their article:

Ritalin (methyphenidate) and Adderall (mixed amphetamine salts), and are prescribed mainly for the treatment of attention deficit hyperactivity disorder (ADHD). Because of their effects on the catecholamine system, these drugs increase executive functions in patients and most healthy normal people, improving their abilities to focus their attention, manipulate information in working memory and flexibly control their responses...A newer drug, modafinil (Provigil), has also shown enhancement potential. Modafinil is approved for the treatment of fatigue caused by narcolepsy, sleep apnoea and shift-work sleep disorder....laboratory studies have shown that modafinil enhances aspects of executive function in rested healthy adults, particularly inhibitory control.

Many people have doubts about the moral status of enhancement drugs for reasons ranging from the pragmatic to the philosophical, including concerns about short-circuiting personal agency and undermining the value of human effort. Kass, for example, has written of the subtle but, in his view, important differences between human enhancement through biotechnology and through more traditional means. Such arguments have been persuasively rejected. Three arguments against the use of cognitive enhancement by the healthy quickly bubble to the surface in most discussions: that it is cheating, that it is unnatural and that it amounts to drug abuse.

In the context of sports, pharmacological performance enhancement is indeed cheating. But, of course, it is cheating because it is against the rules. Any good set of rules would need to distinguish today's allowed cognitive enhancements, from private tutors to double espressos, from the newer methods, if they are to be banned.

As for an appeal to the 'natural', the lives of almost all living humans are deeply unnatural; our homes, our clothes and our food — to say nothing of the medical care we enjoy — bear little relation to our species' 'natural' state. Given the many cognitive-enhancing tools we accept already, from writing to laptop computers, why draw the line here and say, thus far but no further?

Like all new technologies, cognitive enhancement can be used well or poorly. We should welcome new methods of improving our brain function. In a world in which human workspans and lifespans are increasing, cognitive enhancement tools — including the pharmacological — will be increasingly useful for improved quality of life and extended work productivity, as well as to stave off normal and pathological age-related cognitive declines. Safe and effective cognitive enhancers will benefit both the individual and society.

But it would also be foolish to ignore problems that such use of drugs could create or exacerbate. With this, as with other technologies, we need to think and work hard to maximize its benefits and minimize its harms.

This is so kewl.....

From Science Magazine's 'Random Samples' feature:

Meet the Pivo 2, Nissan's compact electric concept car, designed for urban travel with a 360° rotating cabin and wheels that allow the car to scoot sideways for parking. It's one of the stars of the new exhibit "Japan Car: Designs for the Crowded Globe" at London's Science Museum, spotlighting "mobile cells"--small cars fueled by low-polluting electricity or hydrogen and equipped with intelligent driver interfaces.

Other examples include Toyota's iREAL, a sitting version of a Segway that looks like a futuristic wheelchair, with sensors that alert a driver to obstacles down the road, and Mitsubishi's electrical iMiEV, planned for release next year, that can go 160 kilometers on an overnight charge.

Key features of these vehicles are their brains. Pivo 2 has a talking "robotic agent" that offers traffic updates and route information and has voice-recognition capability to answer a driver's questions. The agent is personified by a swiveling head mounted beside the instrument panel that nods and shakes to keep the driver in a "positive frame of mind." "It infers the driver's mood through conversation and facial-monitoring technology," Nissan says. But can you make it shut up? Nissan doesn't say.

Crazy Money

An article by Chelsea Wald continues to make the case that financial theories can not assume that investor behavior is rational. Some clips from that article:

Even the experts seem bewildered by the current economic crisis. Quantitative analysts (quants)--the whiz-kid financial engineers whose algorithms have dominated Wall Street trading in recent years--have watched those algorithms fail. Former Federal Reserve Chair Alan Greenspan acknowledged in October that there was "a flaw in the model that I perceived … defines how the world works."...the classical theory of finance simply does not address human psychology. It looks more like a physical science than a social science--relying on the premises that markets are "efficient,"

Blame has fallen on quants for various aspects of the crisis. First, mathematical models were increasingly used to determine whether someone deserved a loan, bypassing individual judgments. "In the end, there was very little sound credit judgment going into making these credit calls," says Bjorn Flesaker, a senior quant at Bloomberg in New York. Then, quant models were used to rate the riskiness of financial instruments, including the CDOs. "We never necessarily viewed the rating agencies as having the greatest rocket scientists around," says Flesaker, yet investors accepted those ratings, taking on more risk than even they realized...like many of the elements that economists and the media have focused on, the quant models are simply "proximate causes." Ultimately, experts must examine human behavior to find out why the crisis happened. Why did so many people take on mortgages that they would not be able to pay? Why did the best minds of Wall Street ignore warnings about a housing bubble? "The bottom-line question that economists, I think, still are struggling with is: 'Did anybody know that the risks were so great and, if so, why did they continue investing?'

The madness of crowds

Classical finance theory's model of speculative bubbles, such as the dot-com bubble of the late '90s and the recent housing bubble, does not match real-life observations. Classical finance contends that rational investors will always have the best possible portfolio, so they will not buy or sell unless they have extra money to invest or need to cash in their investments. However, researchers have observed that people buy and sell much more often than that during a bubble--with the rate of transactions becoming increasingly manic the bigger the bubble gets.

Lacking a good classical model for stock-market bubbles, Scheinkman, whose work is primarily classical, turned to a concept in behavioral finance. Psychologists have found that people often overestimate the precision of their knowledge. Scheinkman and his Princeton colleague Wei Xiong guessed that overconfident investors would trust their own opinions about the price of an asset, so they would consider others' opinions, if different, a little "crazy," says Scheinkman. Looking to make money off others' crazy opinions, investors would be willing to pay more than they think an asset is actually worth because they believe that they will be able to sell it in the future to an overeager buyer. This process would inflate prices and cause a trading frenzy. Incorporating investor overconfidence into a theoretical model published in 2003 in the Journal of Political Economy, Scheinkman and Xiong were able to recreate more accurately the hyperactive trading in bubbles.

Andrew Lo, a financial economist at MIT, is developing alternative models:

Lo's species behave differently based on what part of their brains they are using. When things go well and people make money, as they did for the past decade, the experience stimulates investors' reward circuitry. This causes them to seek more profits and ignore possible risk, leading, for example, to a bubble. When things take a turn for the worse, panic overrides rational decision-making, leading to a crash. Only when the market is steady does the rational brain take over. Lo is starting to use functional magnetic resonance imaging and other tools of neuroscience to quantify these behaviors and incorporate them into his models. He also needs more real-world data on the way different funds invest money--data that are now secret or that no one bothers to collect.

Although Lo's idiosyncratic approach lies outside of the behavioral and classical theories, he says it reconciles them. "If you were an efficient-markets type, I think you'd be hard-pressed to explain what happened over the last few weeks. And if you were an irrational finance person, you'd be hard-pressed to explain what happened over the previous 10 years. So I think that the only way to reconcile the two is to acknowledge that both are different aspects of the exact same truth."

Behavioral researchers are eager to prove that their ideas mirror nature by using quantitative methods to link them directly to real-life data... Stock pricing lends itself to such studies, because valuing a stock involves conjecture--which is subject to psychological factors--and a lot of stock-market data have recently become available to academic researchers.

In a 2007 paper in the Journal of Economic Perspectives, Wurgler and co-author Malcolm Baker, a financial economist at Harvard Business School, looked for signatures of investor sentiment--irrational optimism or pessimism--in stock-market data since the 1960s. They hypothesized that certain stocks would be more subject to sentiment than others: broadly speaking, stocks for which the true value is difficult to determine. For example, a young, promising company would fit the bill. "The combination of no earnings history and a highly uncertain future allows investors to defend valuations ranging from much too low to much too high," they write.

Comparing the stock-market data with their measure of investor sentiment, they found what they had expected. In optimistic times, difficult-to-value stocks were wildly popular and therefore made much more money than average. In pessimistic times, they were wildly unpopular and therefore made much less money than average. On the other hand, easy-to-value stocks, which are considered safer, were more popular in pessimistic times than optimistic ones, but their prices stayed much closer to average. This helps explain past bubbles in certain types of stocks--say, dot-com stocks in the 1990s--and is also useful for making predictions for the future

Conflict: Altruism's midwife

Bowles has an interesting article in the Nature "Being Human" series. From the editor's comments:

The historical and archaeological records reveal that humans became especially good at killing 'outsiders' from other groups, tribes or nations. Some animals do engage in such conflicts, but humans excel. We are also uniquely receptive to socialization and learning, and can achieve the heights of altruistic behaviour. Economist Samuel Bowles argues that these two extremes may be related: generosity and solidarity towards one's own may have emerged only in combination with hostility towards outsiders. Both may be part of what it is to be human. All essays in the 'Being human' series are available free via http://tinyurl.com/55ncjj.

From the article:

Among ancestral humans, parochial altruists may have provoked conflicts between groups over scarce natural and reproductive resources, and at the same time contributed to a group's success in these conflicts. Altruism would have facilitated the coordination of raiding and ambushing on a scale known in few other animals, while parochialism fuelled the antipathy towards outsiders. Additionally, with the development of projectile weapons, humans became adept at killing from a distance, which would have reduced the costs of aggression.

Support for this idea comes from artificial histories of early human evolution that my co-authors and I simulated by computer. In these simulations, we allowed groups of agents, tolerant or parochial, altruistic or selfish, to interact over thousands of generations under conditions likely to have been experienced by our Late Pleistocene and early Holocene ancestors. We designed the simulations so that violent conflict between two groups is likely if at least one group contains a preponderance of parochialists. We also made each group's fighters the parochial altruists (non-altruists are happy to let someone else do the fighting; tolerant members prefer to stay on friendly terms with outsiders). Thus, the groups with the most parochial altruists tend to win conflicts. Our objective was to see how the frequency of warfare, and the fraction of the different types of agent, would evolve.

In millions of simulated evolutionary histories, the populations emerging after thousands of generations of selection tend to be either tolerant and selfish, with little warfare, or parochial and altruistic with frequent and lethal encounters with other groups. Occasional transitions occur between the selfish peaceful states and the warring altruistic states. But neither altruism nor parochialism ever proliferate singly; they share a common fate, with war the elixir of their success.

Dogs have sense of fairness.

Fountain points to work by Range et al. showing that dogs, like monkeys and chips, have a sense of equity and fairness. A dog may stop obeying a command if it sees that another dog is getting a better deal. Thus, species other than primates show at least a primitive version of inequity aversion, perhaps a precursor of a more sophisticated sensitivity to efforts and payoffs of joint interactions.

I wonder if this behavior also might possibly be related to the extensive breeding selection carried out on dogs over the past several thousand years which has made them, unlike monkeys and apes, very attentive to human moods and intentions.

(Note: I usually compose these blog postings several days in advance of their actual appearance, to keep free of deadline pressure. The downside of this is that I frequently see something I want to mention appearing immediately on, for example, the Op-Ed page of the New York Times. This bit on fairness in dogs is referenced by Gail Collins as relevant to the current U.S. automakers bailout controversy.)

If I Were You: Perceptual Illusion of Body Swapping

The title of this post is also the title of a fascinating article published in PLoS ONE. When tricked by some simple optical and sensory illusions, we can adopt any other human form, no matter how different, as our own. From Carey's review:

The technique is simple. A subject stands or sits opposite the scientist, as if engaged in an interview. Both are wearing headsets, with special goggles, the scientist’s containing small film cameras. The goggles are rigged so the subject sees what the scientist sees: to the right and left are the scientist’s arms, and below is the scientist’s body...To add a physical element, the researchers have each person squeeze the other’s hand, as if in a handshake. Now the subject can see and “feel” the new body. In a matter of seconds, the illusion is complete. In a series of studies, using mannequins and stroking both bodies’ bellies simultaneously, the Karolinska researchers have found that men and women say they not only feel they have taken on the new body, but also unconsciously cringe when it is poked or threatened.

Here is the abstract from the article:

The concept of an individual swapping his or her body with that of another person has captured the imagination of writers and artists for decades. Although this topic has not been the subject of investigation in science, it exemplifies the fundamental question of why we have an ongoing experience of being located inside our bodies. Here we report a perceptual illusion of body-swapping that addresses directly this issue. Manipulation of the visual perspective, in combination with the receipt of correlated multisensory information from the body was sufficient to trigger the illusion that another person's body or an artificial body was one's own. This effect was so strong that people could experience being in another person's body when facing their own body and shaking hands with it. Our results are of fundamental importance because they identify the perceptual processes that produce the feeling of ownership of one's body.

I would love to try this...

My own personal helicopter.

Spread of Happiness - a network analysis.

A report by Fowler and Christakis, as noted by Belluck, is generating interest and controversy. In an analysis covering 20 years of the well known Framington Heart Study they find that happiness spreads like a contagion, that one's happiness is influence by the happiness of friends of friends. The issue is whether the study proved that people became happy because of their social contacts or some unrelated reason. In the same issue of the British Medical Journal, Cohen-Cole and Fletcher critique the work, showing that the statistical analysis used in network studies can detect implausible social network effects in acne, height, and headaches. Here is a summary graphic based on the work provided by the New York Times:

Cool Brain Trick....

I pass on this link to you because of my interest in music, a scale that always seems to be going down, but not getting much lower. It’s an auditory equivalent of an old-fashioned barber pole.

Compendium of brain blogs...

MindBlog reader Kelly points us to this recent posting of "101 Fascinating Brain Blogs"

Changing our body image can change pain perception.

Some remarkable observations by Moseley et al. :

The feeling that our body is ours, and is constantly there, is a fundamental aspect of self-awareness. Although it is often taken for granted, our physical self-awareness, or body image, is disrupted in many clinical conditions. One common disturbance of body image, in which one limb feels bigger than it really is, can also be induced in healthy volunteers by using local anaesthesia or cutaneous stimulation. Here we report that, in patients with chronic hand pain, magnifying their view of their own limb during movement significantly increases the pain and swelling evoked by movement. By contrast, minifying their view of the limb significantly decreases the pain and swelling evoked by movement. These results show a top-down effect of body image on body tissues, thus demonstrating that the link between body image and the tissues is bi-directional.

Larger hippocampus and superior pathfinding in the blind

From Fortin et al, work that confirms how unnecessary vision is for the construction of spatial concepts:

In the absence of visual input, the question arises as to how complex spatial abilities develop and how the brain adapts to the absence of this modality. We explored navigational skills in both early and late blind individuals and structural differences in the hippocampus, a brain region well known to be involved in spatial processing. Thirty-eight participants were divided into three groups: early blind individuals (n = 12; loss of vision before 5 years of age; mean age 33.8 years), late blind individuals (n = 7; loss of vision after 14 years of age; mean age 39.9 years) and 19 sighted, blindfolded matched controls. Subjects undertook route learning and pointing tasks in a maze and a spatial layout task. Anatomical data was collected by MRI. Remarkably, we not only show that blind individuals possess superior navigational skills than controls on the route learning task, but we also show for the first time a significant volume increase of the hippocampus in blind individuals [F(1,36) = 6.314; P ≤ 0.01; blind: mean = 4237.00 mm3, SE = 107.53; sighted: mean = 3905.74 mm3, SE = 76.27], irrespective of whether their blindness was congenital or acquired. Overall, our results shed new light not only on the construction of spatial concepts and the non-necessity of vision for its proper development, but also on the hippocampal plasticity observed in adult blind individuals who have to navigate in this space.

Neural mechanisms underlying memory failure in older adults

Here is a fascinating bit of work from Stevens et al. When failing to encode information older, but not younger, adults show increased activity in brain regions mediating distraction. This continues the developing consensus that aging brains (as I woefully note for mine) have increasing difficulty ignoring distracting information that is irrelevant to the task at hand :

Older adults have reduced memory, primarily for recall, but also for recognition, particularly for unfamiliar faces. Behavioral studies have shown that age-related memory declines are due in part to distraction from impaired inhibition of task-irrelevant input during encoding. Functional magnetic resonance imaging (fMRI) has been used to uncover the sources of memory deficits associated with aging. To date, this work has focused on successful encoding, while the neural correlates of unsuccessful encoding are unknown. Here, we provide novel evidence of a neural mechanism underlying memory failures exclusively affecting older adults. Whereas both younger and older adults showed reduced activation of brain regions important for encoding (e.g., hippocampus) during unsuccessful encoding, only older adults showed increased activity in brain regions mediating distraction (e.g., auditory cortex) and in left prefrontal cortex. Further, these regions were functionally connected with medial parietal areas, previously identified as default mode regions, which may reflect environmental monitoring. Our results suggest that increased distraction from task-irrelevant input (auditory in this case), associated with the unfamiliar and noisy fMRI environment, may increase environmental monitoring. This in turn could hinder suppression of default mode processing, resulting in memory failures in older adults. These findings provide novel evidence of a brain mechanism underlying the behavioral evidence that impaired inhibition of extraneous input during encoding leads to memory failure in older adults and may have implications for the ubiquitous use of fMRI for investigating neurocognitive aging.

Prefrontal regions mediating resistance versus vulnerability to depression.

Koenigs et al., in a study of humans with focal brain lesions, address the causality of depressive symptoms by showing that lesions to different parts of our prefrontal cortex can either enhance or decrease our expression of those symptoms:

The neuroanatomical correlates of depression remain unclear. Functional imaging data have associated depression with abnormal patterns of activity in prefrontal cortex (PFC), including the ventromedial (vmPFC) and dorsolateral (dlPFC) sectors. If vmPFC and dlPFC are critical neural substrates for the pathogenesis of depression, then damage to either area should affect the expression of depressive symptoms. Using patients with brain lesions we show that, relative to nonfrontal lesions, bilateral vmPFC lesions are associated with markedly low levels of depression, whereas bilateral dorsal PFC lesions (involving dorsomedial and dorsolateral areas in both hemispheres) are associated with substantially higher levels of depression. These findings demonstrate that vmPFC and dorsal PFC are critically and causally involved in depression, although with very different roles: vmPFC damage confers resistance to depression, whereas dorsal PFC damage confers vulnerability.

Degraded surroundings degrade behavior

Keizer et al. find support for the "Broken Windows Theory," that suggests that signs of disorderly and petty criminal behavior trigger more disorderly and petty criminal behavior, thus causing the behavior to spread. They find that if people see one norm or rule being violated (such as graffiti or a vehicle parked illegally), they're more likely to violate others--such as littering, or even stealing. Groningen citizens were given the opportunity to steal an envelope that obviously contained a 5 Euro note from a postbox. When the postbox was clean and tidy 13% took the bait; by contrast, 27% stole from a graffitied postbox and 25% from one with litter around it. Other tests showed that people are more likely to litter in the presence of graffiti or abandoned shopping trollies, and after hearing the crackle of illegal fireworks.

Does your cell phone signal damange your DNA? - round two

An exchange in the letters to the editor section of the Nov. 28 Science Magazine:

In her widely cited News of the Week story "Fraud charges cast doubt on claims of DNA damage from cell phone fields" (Science, 29 August, p. 1144), G. Vogel writes, "The only two peer-reviewed scientific papers showing that electromagnetic fields (EMFs) from cell phones can cause DNA breakage are at the center of a misconduct controversy at the Medical University of Vienna." Notwithstanding the allegations on both sides of the fence in this unresolved controversy, Vogel's opening comment and the title of her article are misleading. In fact, there are many other peer-reviewed papers from laboratories in at least seven countries, including the United States, showing that cell phone or similar low-intensity EMFs can break DNA or modulate it structurally [e.g., (1-9)].

Vini G. Khurana
Department of Neurosurgery
The Canberra Hospital
Australian National University
Canberra, ACT, Australia
E-mail: vgkhurana@gmail.com

References

1. R. J. Aitken, L. E. Bennetts, D. Sawyer, A. M. Wiklendt, B. V. King, Int. J. Androl. 28, 171 (2005).
2. W. Baohong et al., Toxicology 232, 311 (2007).
3. J. Y. Kim et al., Environ. Toxicol. 23, 319 (2008).
4. H. Lai, N. P. Singh, Int. J. Radiat. Biol. 69, 513 (1996).
5. S. Lixia et al., Mutat. Res. 602, 135 (2006).
6. R. Paulraj, J. Behari, Mutat. Res. 596, 76 (2006).
7. J. L. Phillips et al., Bioelectrochem. Bioenerget. 45, 103 (1998).
8. T. Nikolova et al., FASEB J. 19, 1686 (2005).
9. M. Mashevich et al., Bioelectromagnetics 24, 82 (2003).

Response
My intention was not to imply that there were only two papers showing any effects of EMFs. There are many publications that show effects of EMFs on DNA, but the citations listed here do not directly contradict the quoted sentence. Some see an effect in combination with other known agents that damage DNA. One finds an effect of microwaves, but in the range of microwave ovens and wireless LANs, not cell phones. Others look at DNA damage (for example, chromosome duplications), but not breakage. Several show mixed results: One finds a decrease in DNA breaks in three sets of exposed cells and an increase in one. Since the story was published, however, I have been made aware of a paper by Yao et al. (1), which also reported single-strand DNA breaks caused by EMFs equivalent to those from cell phones. I regret any misunderstanding the sentence caused.

Gretchen Vogel

Reference

1. K. Yao et al., Mol. Vision 14, 964 (2008).

MindBlog has moved south...

A personal note...I've spent the last week in transition between Madison Wisconsin (where it is 7 degrees farenheit right now) and Fort Lauderdale (where it is 72). I'll be here until mid-April. The picture is of one of my two Abyssinian kittens, looking out my condo window. The cats were great travelers in the car, watched the passing countryside as if they were dogs.