Civilization has caused the decline of human health

I've just finished reading Michael Pollan's "In Defense of Food: An Eater's Manifesto," which is a scary documentation of how modern food technology and 'nutritionism' have significantly increased obesity, diabetes and coronary disease in this century, particularly since the second world war. Thus Ann Gibbons' summary (from presentations at the recent Americal Assoc. of Physical Anthropologists' meeting) of the effects of our earlier transition from hunting/gathering to agriculture makes a lot of sense. A major project has pooled work from 72 researchers to provide the first analysis of data on 11,000 individuals who lived from 3000 years ago until 200 years ago throughout Europe and the Mediterranean. The analysis involves standardized indicators of health from skeletal remains, including stature, dental health, degenerative joint disease, anemia, trauma, and the isotopic signatures of what they ate.

...the health of many Europeans began to worsen markedly about 3000 years ago, after agriculture became widely adopted in Europe and during the rise of the Greek and Roman civilizations. They document shrinking stature and growing numbers of skeletal lesions from leprosy and tuberculosis, caused by living close to livestock and other humans in settlements where waste accumulated. The numbers of dental hypoplasias and cavities also increased as people switched to a grain-based diet with fewer nutrients and more sugars...After a long, slow decline through the Middle Ages, health began to improve in the mid-19th century. Stature increased, probably because of several factors: The little Ice Age ended and food production rose, and better trade networks, sanitation, and medicine developed... But take heed: Overall health and stature in the United States has been declining slightly since the 1950s, possibly because obese Americans eat a poor-quality diet, not unlike early farmers whose diet was less diverse and nutritious than that of hunter-gatherers.

Playing video games improves basic visual function.

Playing action-based video games has been shown to improve attentional processing. Li et al. now find that it also induces long-lasting improvements in contrast sensitivity, a basic visual function that commonly deteriorates with age. These improvements do not happen for an equivalent group who played a non-action video game. Contrast sensitivity is one of the main limiting factors in a wide variety of visual tasks, and it is one of the aspects of vision that is most easily compromised. Here is a useful illustration of contrast sensitivity, from an accompanying review of their work (click to enlarge).

Stimulus contrast and tests of visual function - Top, examples of low- (left) and high-contrast (right) sine wave gratings. Simple stimuli such as these are often used in perceptual learning experiments. Bottom left, an example of a Snellen Eye chart used to measure visual acuity. Bottom right, an example of a Campbell-Robson contrast sensitivity function chart. To see your own contrast sensitivity function, look toward the top of the chart, where the white-black modulations should 'blend in' with the gray background. The inverted-U shaped curve that you see indicates that contrast sensitivity is better for mid-range spatial frequencies than for low or high ones. Playing action-based video games improves contrast sensitivity, effectively 'pushing' this curve upwards.

Special nerves for pleasant social touch.

Neural correlates of pleasure have been studied mainly in our central nervous systems (brain and spinal cord). Löken et al., look at activity in our peripheral nervous system, specifically a small class of axons without myelin wrapping that send pressure information from skin to the central nervous system. They demonstrate a relationship between positive hedonic sensation and coding at the level of these peripheral afferent nerves, suggesting that C-tactile fibers contribute critically to pleasant touch. Soft brush stroking on hairy skin was perceived as most pleasant when it was delivered at velocities that were most effective at activating C-tactile afferents (1–10 cm s-1), with a linear correlation between C-tactile impulse frequency and pleasantness ratings. Here is the abstract:

Pleasant touch sensations may begin with neural coding in the periphery by specific afferents. We found that during soft brush stroking, low-threshold unmyelinated mechanoreceptors (C-tactile), but not myelinated afferents, responded most vigorously at intermediate brushing velocities (1-10 cm s^-1), which were perceived by subjects as being the most pleasant. Our results indicate that C-tactile afferents constitute a privileged peripheral pathway for pleasant tactile stimulation that is likely to signal affiliative social body contact.

Monday morning music - Chopin Nocturne in C# minor - posthumous

I've finally gotten through re-entry details after my return to Wisconsin, and started recording some pieces -using the Steinway B in my home on Twin Valley Rd. in the Town of Middleton, just west of Madison, WI. (The pictures below the video are spring flowers in the front yard that I can see from the piano.) This reading of the posthumous Chopin Nocturne in C# minor is a more rapid and robust one than many. I may decide to do it again, or do a second version.

Risk-dependent reward value signal in human prefrontal cortex

From Tobler et al., observations on brain activity during risk-reward situations that emphasize lateral prefrontal cortex, while the risk-reward study referenced in my April 25 post points at ventral medial prefrontal cortex. It is because of this kind of variation in results reported by different labs that one has to wait a bit for a concensus to emerge on structure-function correlations. Here is the Tobler et al. abstract:

When making choices under uncertainty, people usually consider both the expected value and risk of each option, and choose the one with the higher utility. Expected value increases the expected utility of an option for all individuals. Risk increases the utility of an option for risk-seeking individuals, but decreases it for risk averse individuals. In 2 separate experiments, one involving imperative (no-choice), the other choice situations, we investigated how predicted risk and expected value aggregate into a common reward signal in the human brain. Blood oxygen level dependent responses in lateral regions of the prefrontal cortex increased monotonically with increasing reward value in the absence of risk in both experiments. Risk enhanced these responses in risk-seeking participants, but reduced them in risk-averse participants. The aggregate value and risk responses in lateral prefrontal cortex contrasted with pure value signals independent of risk in the striatum. These results demonstrate an aggregate risk and value signal in the prefrontal cortex that would be compatible with basic assumptions underlying the mean-variance approach to utility.

Our amygdala is more responsive to pleasant words

Interesting observations from Herbert et al. Some brain correlates of how we remember pleasant better than unpleasant reading content. Their event-related functional magnetic resonance imaging (fMRI) study:

...investigated brain activity elicited by emotional adjectives during silent reading without specific processing instructions. Fifteen healthy volunteers were asked to read a set of randomly presented high-arousing emotional (pleasant and unpleasant) and low-arousing neutral adjectives. Silent reading of emotional in contrast to neutral adjectives evoked enhanced activations in visual, limbic and prefrontal brain regions. In particular, reading pleasant adjectives produced a more robust activation pattern in the left amygdala and the left extrastriate visual cortex than did reading unpleasant or neutral adjectives. Moreover, extrastriate visual cortex and amygdala activity were significantly correlated during reading of pleasant adjectives. Furthermore, pleasant adjectives were better remembered than unpleasant and neutral adjectives in a surprise free recall test conducted after scanning. Thus, visual processing was biased towards pleasant words and involved the amygdala, underscoring recent theoretical views of a general role of the human amygdala in relevance detection for both pleasant and unpleasant stimuli. Results indicate preferential processing of pleasant information in healthy young adults and can be accounted for within the framework of appraisal theory.

Reminders of age undermine memory

Nagourny notes a study in which researchers found that when older volunteers took a series of cognitive tests after being given hints that their age might affect the results, they did less well.

REM sleep enhances storage of emotional memories

From Nishida et al:

Both emotion and sleep are independently known to modulate declarative memory. Memory can be facilitated by emotion, leading to enhanced consolidation across increasing time delays. Sleep also facilitates offline memory processing, resulting in superior recall the next day. Here we explore whether rapid eye movement (REM) sleep, and aspects of its unique neurophysiology, underlie these convergent influences on memory. Using a nap paradigm, we measured the consolidation of neutral and negative emotional memories, and the association with REM-sleep electrophysiology. Subjects that napped showed a consolidation benefit for emotional but not neutral memories. The No-Nap control group showed no evidence of a consolidation benefit for either memory type. Within the Nap group, the extent of emotional memory facilitation was significantly correlated with the amount of REM sleep and also with right-dominant prefrontal theta power during REM. Together, these data support the role of REM-sleep neurobiology in the consolidation of emotional human memories, findings that have direct translational implications for affective psychiatric and mood disorders.

Friends and a long life.

I have been meaning to pass on this article by Parker-Pope, which notes several studies on the correlation between social networks, longevity, and psychological well-being.

Features of Einstein's brain.

Clips from Michael Balter's recent report:

The first anatomical study of Einstein's brain was published in 1999, by a team led by Sandra Witelson, a neurobiologist at McMaster University in Hamilton, Canada..Witelson's team found that Einstein's parietal lobes--which are implicated in mathematical, visual, and spatial cognition--were 15% wider than normal parietal lobes...One parameter that did not explain Einstein's mental prowess, however, was the size of his brain: At 1230 grams, it fell at the low end of average for modern humans. Now Dean Falk, an anthropologist at Florida State University in Tallahassee...claims to have identified a number of previously unrecognized unusual features in Einstein's brain. They include a pronounced knoblike structure in the part of the motor cortex that controls the left hand; in other studies, similar "knobs" have been associated with musical ability. (Einstein had played the violin avidly since childhood.)

Like Witelson's team, Falk found that Einstein's parietal lobes were larger; comparing the photographs of Einstein's brain with a second previously published set of 58 control brains, Falk also identified a very rare pattern of grooves and ridges in the parietal regions of both sides of the brain that she speculates might somehow be related to Einstein's superior ability to conceptualize physics problems. Indeed, during his lifetime, Einstein often claimed that he thought in images and sensations rather than in words. Falk speculates that Einstein's talent as "a synthetic thinker" may have arisen from the unusual anatomy of his parietal cortex.

Juicing up your brain

"Every era has its defining drug. Neuroenhancers are perfectly suited for our efficiency-obsessed, BlackBerry-equipped office culture." Margaret Talbot writes an interesting article on the underground world of performance enhancing drugs in the New Yorker, covering benefits and pitfalls. Given that chemicals enhancing our sex life and beauty are commonly taken, it is not surprising that there is growing use of drugs enhancing our smarts.

The emerging bottom-up world order?

Two interesting articles on the kind of world order (or disorder) that is likely to emerge in the 21st century. David Brooks notes that:

We face a series of decentralized, transnational threats: jihadi terrorism, a global financial crisis, global warming, energy scarcity, nuclear proliferation and...possible health pandemics like swine flu...Do we build centralized global institutions that are strong enough to respond to transnational threats? Or do we rely on diverse and decentralized communities and nation-states?..The response to swine flu suggests that a decentralized approach is best. This crisis is only days old, yet we’ve already seen a bottom-up, highly aggressive response.

First, the decentralized approach is much faster. Mexico responded unilaterally and aggressively to close schools and cancel events. The U.S. has responded with astonishing speed, considering there are still few illnesses and just one hospitalization...Second, the decentralized approach is more credible. It is a fact of human nature that in times of crisis, people like to feel protected by one of their own. They will only trust people who share their historical experience, who understand their cultural assumptions about disease and the threat of outsiders and who have the legitimacy to make brutal choices...Finally, the decentralized approach has coped reasonably well with uncertainty. It is clear from the response, so far, that there is an informal network of scientists who have met over the years and come to certain shared understandings about things like quarantining and rates of infection.

A single global response would produce a uniform approach. A decentralized response fosters experimentation...The correct response to these dynamic, decentralized, emergent problems is to create dynamic, decentralized, emergent authorities: chains of local officials, state agencies, national governments and international bodies that are as flexible as the problem itself.

Kakutani reviews "The Age of the Unthinkable" by J. C. Ramo. Ramo argues:

that today’s complex, interconnected, globalized world requires policy makers willing to toss out old assumptions (about cause and effect, deterrence and defense, nation states and balances of power) and embrace creative new approaches...The central image that Mr. Ramo uses to evoke what he calls this “age of surprise” is Per Bak’s sand pile — that is, a sand pile described some two decades ago by the Danish-American physicist Per Bak, who argued that if grains of sand were dropped on a pile one at a time, the pile, at some point, would enter a critical state in which another grain of sand could cause a large avalanche — or nothing at all. It’s a hypothesis that shows that a small event can have momentous consequences and that seemingly stable systems can behave in highly unpredictable ways...It’s also a hypothesis that Mr. Ramo employs as a metaphor for a complex world in which changes — in politics, ecosystems or financial markets — take place not in smooth, linear progressions but as sequences of fast, sometimes catastrophic events.

So how should leaders cope with the sand-pile world? How can they learn to “ride the earthquake” and protect their countries from the worst fallout of such tremors? Mr. Ramo suggests that they must learn to build resilient societies with strong immune systems: instead of undertaking the impossible task of trying to prepare for every possible contingency, they ought to focus on things like national health care, construction of a better transport infrastructure and investment in education...leaders should develop ways of looking at problems that focus more on context than on reductive answers. And he talks about people learning to become gardeners instead of architects, of embracing Eastern ideas of indirection instead of Western patterns of confrontation, of seeing “threats as systems, not objects.”

Born to be Good

I have just thoroughly enjoyed a reading of Dacher Keltner's book "Born to be Good." Keltner, a former student of Paul Ekman, starts with Darwin's acute observations on human emotions, describes Ekman's pioneering work on innate human facial communication, and then proceeds through chapters on embarassment, smiling, laughing, teasing, touching, compassion and awe. He documents work of his own and others that demonstrates evolved stereotyped facial and body movement patterns characteristic of each of these behaviors. The video is a brief promo of the book.

The quest for compassion

Greg Miller writes (PDF here) on the establishment of a new institute at Stanford University for the scientific study of compassion.

Enlightenment therapy?

I found myself disappointed by what at first appeared to be a promising article in this past Sunday’s NY Times magazine: “Enlightenment Therapy” by Chip Brown. It relates the interaction of a 63-year old professor who renounced a tenured professorship in philosophy to become a Zen Buddhist monk 35 years ago and a psychotherapist who has published a series of books on psychotherapy and Buddhism. A detailed account of the professor’s childhood traumas, and their effect on his adult life, is given, but it seems a pity that the article is almost completely lacking in any broader reference to other religious figures and psychiatrists (Alan Wallace and Mark Epstein come to mind) who have been very influential in integrating Buddhist and Psychoanalytic insights. Even more puzzling is the absence of reference to discoveries in cognitive neuroscience that validate the insights of both traditions (noted by integrative writers such as philosopher Thomas Metzinger and trade writer Alan Nisker).

Econophysics - a model that explains the crash

I thought I would pass on this report by Cho, slightly edited, on a model that shows leverage to be the root of the current financial turmoil:

During the 1990s, physicists flocked to Wall Street and other financial hubs, eager to turn their analytical skills and phenomenological mindset to the problem of making a killing. Now that the world's stock markets are in retreat, they've turned to explaining why markets crash. According to one new analysis, leverage—the practice by hedge funds and other investors of borrowing money to buy investments—is the root of many nettlesome properties of financial markets that classical economics cannot explain, including a propensity to crash.

Given that in the buildup to the recent global economic meltdown hedge funds had been leveraging their deals by ratios of 30-to-1 (that is, borrowing $30 for every $1 of their own that they put in), it may seem obvious that massive leverage leads to trouble. But Stefan Thurner, an econophysicist and director of the complex systems research group at the Medical University of Vienna, Austria, and colleagues say their model shows that many of the distinctive statistical properties of financial markets emerge together as rates of leverage climb.

Financial markets behave in ways that... classical economic theory cannot explain. Classical economics assumes that the fluctuations in stock prices conform to a so-called Gaussian distribution—a bell curve that gives little probability to large swings. In reality, the distribution has "fat tails" that make big changes more likely, and the shapes of those tails conform to a mathematical formula known as a power law. Classical economics assumes that the fluctuations are uncorrelated from one moment to the next, whereas big swings in prices tend to come together in the so-called clustering of volatility.

To try to explain those characteristics, over the past 5 years Thurner and colleagues have developed an "agent-based model" of a market. In such a computer model, virtual agents of various types interact according to certain rules, like robots playing a game. The researchers included hedge funds that could borrow to make their investments; banks to loan the money; "noise investors" who, like day traders, simply react to the market and have no other insight into the value of assets; and general investors who played the role of, for example, state pension funds.

The model contains more than a dozen adjustable parameters. However, Thurner and colleagues found that the maximum level of leverage exerts a curious, unifying effect. If they forbade leverage, the market behaved largely as classical economics would predict. But as they increased the maximum leverage, the characteristics of real markets emerged together. "We can explain the fat tails, the right [power law], the clustering of volatility, all this," Thurner says. And when the leverage limit climbed to levels of 5-to-1 and beyond, the market became unstable and hedge funds went bust much more often.

Thurner, who managed a hedge fund that tanked, says that limiting leverage should help prevent crashes. He admits, however, that he would not have embraced that idea when the market was still going strong.

Childhood poverty, chronic stress, and adult working memory

Sobering observations from Evans and Schaumberg presented in an open access article in PNAS:

The income–achievement gap is a formidable societal problem, but little is known about either neurocognitive or biological mechanisms that might account for income-related deficits in academic achievement. We show that childhood poverty is inversely related to working memory in young adults. Furthermore, this prospective relationship is mediated by elevated chronic stress during childhood. Chronic stress is measured by allostatic load, a biological marker of cumulative wear and tear on the body that is caused by the mobilization of multiple physiological systems in response to chronic environmental demands.

Failure to find effect of estrogen or testosterone on economic behavior.

Zethraeus et al.(open access) obtain a result that is contrary to expectations generated by previous studies:

Existing correlative evidence suggests that sex hormones may affect economic behavior such as risk taking and reciprocal fairness. To test this hypothesis we conducted a double-blind randomized study. Two-hundred healthy postmenopausal women aged 50–65 years were randomly allocated to 4 weeks of treatment with estrogen, testosterone, or placebo. At the end of the treatment period, the subjects participated in a series of economic experiments that measure altruism, reciprocal fairness, trust, trustworthiness, and risk attitudes. There was no significant effect of estrogen or testosterone on any of the studied behaviors.

The sapient paradox

Merlin Donald has written a series of fascinating books on the emergence of modern humans, one of which I used extensively as a reference in my "Biology of Mind" book. He now reviews a special issue of the Proceedings of the Royal Society devoted to a conference at the Univ. of Cambridge titled ‘Archaeology meets neuroscience’. His review (PDF here) is well worth reading.

A major link between archaeology and neuroscience is provided by cognitive science, which has a foot in both camps. Some aspects of cognition, such as literacy, mathematics and music are obviously cultural in origin. Others, such as attention, perception and action stem directly from the design of the central nervous system. These two influences, brain and culture, work together in forming human cognition, and cognitive scientists find themselves in the position of having to explain many of the higher cognitive capabilities of human beings in terms of hybrid brain-culture mechanisms. Evolutionary models are one important way of ordering the evidence on hybrid mechanisms, and epigenetic factors may prove to be paramount in this process.

The ‘sapient paradox’ refers to a puzzle that has been a thorn in the side of prehistory researchers for some time. There seems to have been a long — in fact, inordinately long — delay between the emergence of anatomically modern humans and our later cultural flowering. Both genetic and archaeological evidence converge on the conclusion that the ‘speciation’ phase of sapient humans occurred in Africa at least 70 000–100 000 years BP, and possibly earlier, and all modern humans are descended from those original populations...a later period, extending from 10 000 years ago to the present, is referred to as the ‘tectonic’ phase. This has been a period of greatly accelerated change, stepping relatively quickly through several different levels of social and material culture, including the domestication of plants and animals, sedentary societies, cities and advanced metallurgy. It has culminated in many recent changes, giving us dramatic innovations, such as skyscrapers, atomic energy and the internet. The paradox is that there was a gap of well over 50 000 years between the speciation and tectonic phases. The acceleration of recent cultural change is especially puzzling when viewed in the light of the hundreds of thousands of years it took our ancestors to master fire, stone tool making and coordinated seasonal hunting.

Merlin's review succinctly summarizes the views of conference contributors on these issues.

Risk and reward processing in different prefrontal areas

More information from Bechara and collaborators on how decisions are parceled out within the prefrontal cortex:

Making a risky decision is a complex process that involves evaluation of both the value of the options and the associated risk level. Yet the neural processes underlying these processes have not so far been clearly identified. Using functional magnetic resonance imaging and a task that simulates risky decisions, we found that the dorsal region of the medial prefrontal cortex (MPFC) was activated whenever a risky decision was made, but the degree of this activity across subjects was negatively correlated with their risk preference. In contrast, the ventral MPFC was parametrically modulated by the received gain/loss, and the activation in this region was positively correlated with an individual's risk preference. These results extend existing neurological evidence by showing that the dorsal and ventral MPFC convey different decision signals (i.e., aversion to uncertainty vs. approach to rewarding outcomes), where the relative strengths of these signals determine behavioral decisions involving risk and uncertainty.