Wielding power increases testosterone in women.

Anders et al. provide evidence for a gender→testosterone pathway:

Significance

Human biology is typically studied within the framework of sex (evolved, innate factors) rather than gender (sociocultural factors), despite some attention to nature/nurture interactions. Testosterone is an exemplar of biology studied as natural difference: men’s higher testosterone is typically seen as an innate “sex” difference. However, our experiment demonstrates that gender-related social factors also matter, even for biological measures. Gender socialization may affect testosterone by encouraging men but not women toward behaviors that increase testosterone. This shows that research on human sex biology needs to account for gender socialization and that nurture, as well as nature, is salient to hormone physiology. Our paper provides a demonstration of a novel gender→testosterone pathway, opening up new avenues for studying gender biology.

Abstract

Testosterone is typically understood to contribute to maleness and masculinity, although it also responds to behaviors such as competition. Competition is crucial to evolution and may increase testosterone but also is selectively discouraged for women and encouraged for men via gender norms. We conducted an experiment to test how gender norms might modulate testosterone as mediated by two possible gender→testosterone pathways. Using a novel experimental design, participants (trained actors) performed a specific type of competition (wielding power) in stereotypically masculine vs. feminine ways. We hypothesized in H1 (stereotyped behavior) that wielding power increases testosterone regardless of how it is performed, vs. H2 (stereotyped performance), that wielding power performed in masculine but not feminine ways increases testosterone. We found that wielding power increased testosterone in women compared with a control, regardless of whether it was performed in gender-stereotyped masculine or feminine ways. Results supported H1 over H2: stereotyped behavior but not performance modulated testosterone. These results also supported theory that competition modulates testosterone over masculinity. Our findings thus support a gender→testosterone pathway mediated by competitive behavior. Accordingly, cultural pushes for men to wield power and women to avoid doing so may partially explain, in addition to heritable factors, why testosterone levels tend to be higher in men than in women: A lifetime of gender socialization could contribute to “sex differences” in testosterone. Our experiment opens up new questions of gender→testosterone pathways, highlighting the potential of examining nature/nurture interactions and effects of socialization on human biology.

Flip-Flops in medical advice.

I want to forward readers some clips I've taken from a review by Zuger of a recent book "Ending Medical Reversal" by Prasad and Cifu. After glancing through the following you might want to also have a look a this article by Span on the over-treatment of older patients.

Prasad and Cifu... have set themselves the task of figuring out how often modern medicine reverses itself, analyzing why it happens, and suggesting ways to make it stop...[they] extrapolate from past reversals to conclude that about 40 percent of what we consider state-of-the-art health care is likely to turn out to be unhelpful or actually harmful.

Recent official flip-flops include habits of treating everything from lead poisoning to blood clots, from kidney stones to heart attacks. One reversal concerned an extremely common orthopedic procedure, the surgical repair of the meniscus in the knee, which turns out to be no more effective than physical therapy alone. The interested reader can plow through almost 150 disproved treatments in the book’s appendix.

What could make more sense, after all, than finding some cancers early, fixing a piece of torn cartilage, closing a hole in the heart, and propping open blood vessels that have become perilously narrow? And yet not one of these helpful interventions has been shown to make a difference in the health or survival of patients who obediently line up to have them done.

“Often the study of the study of how therapies should work is much more extensive and comes before the study of whether therapies do work,” the authors write. Thus a medical culture based on “should work” rather than “does work” is condemned to constantly correct itself when the science is finally evaluated for outcomes that matter.

To fix this constant backtracking would require nothing less than a revolution in how doctors are trained, with an emphasis on the proven and practical rather than the theoretical. (It would also require a second revolution in how doctors practice, with less prestige and remuneration for coming up with new ideas and more for validating old ones.)

Divided we fall - putting social progress on par with prosperity

Laura Levis, in Harvard Magazine, describes work of Porter and Stern, who have developed a social progress index that:

...ranks 133 countries on multiple dimensions of social and environmental performance in three main categories: Basic Human Needs (food, water, shelter, safety); Foundations of Wellbeing (basic education, information, health, and a sustainable environment); and Opportunity (freedom of choice, freedom from discrimination, and access to higher education). Porter considers the index “the most comprehensive framework developed for measuring social progress, and the first to measure social progress independently of gross domestic product (GDP)."

The United States may rank sixth among countries in terms of GDP per capita, but its results on the Social Progress Index are lackluster. It is sixteenth overall in social progress: well below Canada, the United Kingdom, Germany, and Japan in several key areas, including citizens’ quality of life and provision of basic human needs. The nation ranks thirtieth in personal safety, forty-fifth in access to basic knowledge, sixty-eighth on health and wellness, and seventy-fourth in ecosystem sustainability. “We had a lot of firsts in social progress over the years in America,” Porter points out, “but we kind of lost our rhythm and our momentum.”

About 20 or 30 years ago, for reasons Porter says he cannot completely explain, the rate of progress in America began to slow down. As a society, he points out, Americans slowly became more divided, and important priorities such as healthcare, education, and politics suffered. “We had gridlock, whether it’s unions or whether it’s ideological differences, and—although we’ve made some big steps in certain areas of human rights like gay rights—if you think about the really core things like our education system and our health system, we’re just not moving,” he says. “I think our political system isn’t helping, because we’re all about political gains and blocking the other guy, rather than compromising and getting things done.”

A personal note, the Steinway B now in Fort Lauderdale - some Chopin

After a few tense moments,  my Steinway B is now moved from Wisconsin to Florida.

I've upgraded my video and audio recording equipment, finally got the bugs out of the process, and thought I would pass on my first test recording - of a Chopin Nocturne that I plan to play at a recital next February here in Fort Lauderdale.  The vers. 3 refers to the fact that this is the third recording of this piece that I have put on my YouTube channel.

 

Neuropolitics - reading the electorate's mind.

Members of our two major political parties increasingly seem to inhabit alternative realities that are utterly incomprehending of each other. How about reinforcing these bubbles with technology for feeding blocks of voters only what they want to hear? A NYTimes piece by Kevin Randall describes some really spooky new political tools: digital campaign signs that note the facial and emotional reactions of those watching their message and tally emotional reactions like happiness, surprise, anger, disgust, fear and sadness. This permits alteration of the message to elicit desired responses. Such devices have been used in Mexico, Poland, Turkey, and probably the U.S.

In Mexico, President Enrique Peña Nieto’s campaign and his party, the Institutional Revolutionary Party, or PRI, employed tools to measure voters’ brain waves, skin arousal, heart rates and facial expressions during the 2012 presidential campaign. More recently, the party has been using facial coding to help pick its best candidates, one consultant says. Some officials even speak openly about their embrace of neuropolitical techniques, and not just for campaigning, but for governing as well.

Neuromarketing consultants say they are conducting research like this in more than a dozen countries, including Argentina, Brazil, Costa Rica, El Salvador, Russia, Spain and, to a much lesser extent, the United States.

One neuromarketing firm says it has worked for a Hillary Rodham Clinton presidential campaign committee to help it improve its targeting and messages.

David Plouffe, President Obama’s former campaign manager, said the tools “would be new ground for political campaigns...The richness of this data compared to what is gathered today in testing ads or evaluating speeches and debates, which is the trusty old dial test and primitive qualitative methods, is hard to comprehend. It gets more to emotion, intensity and a more complex understanding of how people are reacting.”

Added note: Mexico's governing party, the PRI, has now said it will no longer employ the techniques described above.

The Brain with David Eagleman

I want to point MindBlog readers who aren't already aware of the David Eagleman PBS series on the brain to its description on the PBS website. The episodes can be viewed on mobile devices, in your web browser, etc. I found episode 4 "Why Do I Need You?," on our social brains, to be a very compelling one.

More evolution cartoons

I pass this on from a recent seminar presentation to the Chaos group at the Univ. of Wisconsin... There must be hundreds of cartoons that take a different tack on this sequence:

Good and bad stress in the Brain - The inverted U

I want to pass on a bit of commentary by Robert Sapolsky, in a special issue of Nature Neuroscience that focuses on stress, that presents a clear and lucid description of "good stress" and "bad stress."

...to a large extent, the effects of stress in the brain form a nonlinear 'inverted-U' dose-response curve as a function of stressor severity: the transition from the complete absence of stress to mild stress causes an increase in endpoint X, the transition from mild-to-moderate stress causes endpoint X to plateau and the transition from moderate to more severe stress decreases endpoint X.

A classic example of the inverted-U is seen with the endpoint of synaptic plasticity in the hippocampus, where mild-to-moderate stressors, or exposure to glucocorticoid concentrations in the range evoked by such stressors, enhances primed burst potentiation, whereas more severe stressors or equivalent elevations of glucocorticoid concentrations do the opposite11. This example also demonstrates an elegant mechanism for generating such an inverted-U12. Specifically, the hippocampus contains ample quantities of receptors for glucocorticoids. These come in two classes. First, there are the high-affinity low-capacity mineralocorticoid receptors (MRs), which are mostly occupied under basal, non-stress conditions and in which occupancy increases to saturating levels with mild-to-moderate stressors. In contrast, there are the low-affinity, high-capacity glucocorticoid receptors (GRs), which are not substantially occupied until there is major stress-induced glucocorticoid secretion. Critically, it is increased MR occupancy that enhances synaptic plasticity, whereas increased occupancy of GRs impairs it; the inverted-U pattern emerges from these opposing effects.

..in general, the effects of mild-to-moderate stress (that is, the left side of the U) are salutary, whereas those of severe stress are the opposite. In other words, it is not the case that stress is bad for you. It is major stress that is bad for you, whereas mild stress is anything but; when it is the optimal amount of stress, we love it. What constitutes optimal good stress? It occurs in a setting that feels safe; we voluntarily ride a roller coaster knowing that we are risking feeling a bit queasy, but not risking being decapitated. Moreover, good stress is transient; it is not by chance that a roller coaster ride is not 3 days long. And what is mild, transient stress in a benevolent setting? For this we have a variety of terms: arousal, alertness, engagement, play and stimulation (Fig. 1). The upswing of the inverted-U is the domain of any good educator who intuits the ideal space between a student being bored and being overwhelmed, where challenge is energized by a well-calibrated motivating sense of 'maybe'; after all, it is in the realm of plausible, but not guaranteed, reward that anticipatory bursts of mesolimbic dopamine release are the greatest19. And the downswing of the inverted-U is, of course, the universe of “stress is bad for you”. Thus, the ultimate goal of those studying stress is not to 'cure' us of it, but to optimize it.

Figure 1: Conceptualization of the inverted-U in the context of the benefits and costs of stress.

A broad array of neurobiological endpoints show the same property, which is that stress in the mild-to-moderate range (roughly corresponding to 10–20 μg dl−1 of corticosterone, the species-specific glucocorticoid of rats and mice) has beneficial, salutary effects; subjectively, when exposure is transient, we typically experience this range as being stimulatory. In contrast, both the complete absence of stress, or stress that is more severe and/or prolonged than that in the stimulatory range, have deleterious effects on those same neurobiological endpoints. The absence of stress is subjectively experienced as understimulatory by most, whereas the excess is typically experienced as overstimulatory, which segues into 'stressful'. Many of the inverted-U effects of stress in the brain are explained by the dual receptor system for glucocorticoids, where salutary effects are heavily mediated by increasing occupancy of the high-affinity, low-capacity MRs and deleterious effects are mediated by the low-affinity, high-capacity GRs.

Shift happens

I'm passing on this interesting and scary 2014 video about our future, sent to me by a friend.

How to live what we don't believe.

Veteran readers of MindBlog will be aware that a continuing issue has been the problem of what to do with our understanding of how our brains really work - the fact that there is no free will, morality, or "I" of the sort we commonly suppose. (See for example "The I-Illusion," "Having no self..," "Are we really conscious.")

Two recent Op-Ed pieces in the NYTimes continue this thread: Risen and Nussbaum on "Believing What You Don't Believe" and William Irwin on "How to Live a Lie." Irwin considers morality, religion, and finally, free will:

When a novel or movie is particularly engrossing, our reactions to it may be involuntary and resistant to our attempts to counter them. We form what the philosopher Tamar Szabo Gendler calls aliefs — automatic belief-like attitudes that contrast with our well considered beliefs.

Like our involuntary screams in the theater, there may be cases of involuntary moral fictionalism or religious fictionalism as well. Among philosophical issues, though, free will seems to be the clearest case of involuntary fictionalism. It seems clear that I have free will when, for example, I choose from many options to order pasta at a restaurant. Yet few, if any, philosophical notions are harder to defend than free will. Even dualists, who believe in a nonmaterial soul, run into problems with divine foreknowledge. If God foresaw that I would order pasta, then was I really free to do otherwise, to order steak?

In the traditional sense, having free will means that multiple options are truly available to me. I am not a computer, running a decision-making program. No matter what I choose, I could have chosen otherwise. However, in a materialist, as opposed to dualist, worldview, there is no place in the causal chain of material things for the will to act in an uncaused way. Thus only one outcome of my decision-making process is possible. Not even quantum indeterminacy could give me the freedom to order steak. The moment after I recognize this, however, I go back to feeling as if my decision to order pasta was free and that my future decision of what to have for dessert will also be free. I am a free will fictionalist. I accept that I have free will even though I do not believe it.

Giving up on the possibility of free will in the traditional sense of the term, I could adopt compatibilism, the view that actions can be both determined and free. As long as my decision to order pasta is caused by some part of me — say my higher order desires or a deliberative reasoning process — then my action is free even if that aspect of myself was itself caused and determined by a chain of cause and effect. And my action is free even if I really could not have acted otherwise by ordering the steak.

Unfortunately, not even this will rescue me from involuntary free will fictionalism. Adopting compatibilism, I would still feel as if I have free will in the traditional sense and that I could have chosen steak and that the future is wide open concerning what I will have for dessert. There seems to be a “user illusion” that produces the feeling of free will.

William James famously remarked that his first act of free will would be to believe in free will. Well, I cannot believe in free will, but I can accept it. In fact, if free will fictionalism is involuntary, I have no choice but to accept free will. That makes accepting free will easy and undeniably sincere. Accepting the reality of God or morality, on the other hand, are tougher tasks, and potentially disingenuous.

Amazing…. Robots learn coordinated behavior from scratch.

Der and Martius suggest that a novel plasticity rule can explain the development of sensorimotor intelligence, without having to postulate higher-level constructs such as intrinsic motivation, curiosity, or a specific reward system.  This seems to me to be groundbreaking and fascinating work. I pass on their overview video, and then some context from their introduction, which I recommend that you read.  Here is their abstract. (I don't even begin to understand the description of their feed-forward controller network and humanoid robot, which follows a “chaining together what changes together” rule. I can send motivated readers a PDF of the whole article with technical details and equations.)

 

Research in neuroscience produces an understanding of the brain on many different levels. At the smallest scale, there is enormous progress in understanding mechanisms of neural signal transmission and processing. At the other end, neuroimaging and related techniques enable the creation of a global understanding of the brain’s functional organization. However, a gap remains in binding these results together, which leaves open the question of how all these complex mechanisms interact. This paper advocates for the role of self-organization in bridging this gap. We focus on the functionality of neural circuits acquired during individual development by processes of self-organization—making complex global behavior emerge from simple local rules.

Donald Hebb’s formula “cells that fire together wire together” may be seen as an early example of such a simple local rule which has proven successful in building associative memories and perceptual functions. However, Hebb’s law and its successors...are restricted to scenarios where the learning is driven passively by an externally generated data stream. However, from the perspective of an autonomous agent, sensory input is mainly determined by its own actions. The challenge of behavioral self-organization requires a new kind of learning that bootstraps novel behavior out of the self-generated past experiences.

This paper introduces a rule which may be expressed as “chaining together what changes together.” This rule takes into account temporal structure and establishes contact to the external world by directly relating the behavioral level to the synaptic dynamics. These features together provide a mechanism for bootstrapping behavioral patterns from scratch.

This synaptic mechanism is neurobiologically plausible and raises the question of whether it is present in living beings. This paper aims to encourage such initiatives by using bioinspired robots as a methodological tool. Admittedly, there is a large gap between biological beings and such robots. However, in the last decade, robotics has seen a change of paradigm from classical AI thinking to embodied AI which recognizes the role of embedding the specific body in its environment. This has moved robotics closer to biological systems and supports their use as a testbed for neuroscientific hypotheses.

We deepen this argument by presenting concrete results showing that the proposed synaptic plasticity rule generates a large number of phenomena which are important for neuroscience. We show that up to the level of sensorimotor contingencies, self-determined behavioral development can be grounded in synaptic dynamics, without having to postulate higher-level constructs such as intrinsic motivation, curiosity, or a specific reward system. This is achieved with a very simple neuronal control structure by outsourcing much of the complexity to the embodiment [the idea of morphological computation].

Trusting robots, but not androids

Gilbert Chin points to work by Mathur and Reichling in the Journal Cognition.

Robots collect warehoused books, weld car parts together, and vacuum floors. As the number of android robots increases, however, concerns about the “uncanny valley” phenomenon—that people dislike a vaguely human-like robot more than either a machine-like robot or a real human—remain. Mathur and Reichling revisited whether human reactions to android robots exhibit an uncanny valley effect, using a set of 80 robot head shots gathered from the Internet and a systematically morphed set of six images extending from entirely robot to entirely human. Humans did adhere to the uncanny valley curve when rating the likeability of both sets of faces; what's more, this curve also described the extent to which those faces were trusted.

Here's the summary from the paper:

Highlights

• Likability ratings of a large sample of real robot faces had a robust Uncanny Valley.
• Digitally composed robot face series demonstrated a similar Uncanny Valley.
• The Uncanny Valley may subtly alter humans’ trusting behavior toward robot partners.
• Category confusion may occur in the Uncanny Valley but did not mediate the effect. 

Abstract

Android robots are entering human social life. However, human–robot interactions may be complicated by a hypothetical Uncanny Valley (UV) in which imperfect human-likeness provokes dislike. Previous investigations using unnaturally blended images reported inconsistent UV effects. We demonstrate an UV in subjects’ explicit ratings of likability for a large, objectively chosen sample of 80 real-world robot faces and a complementary controlled set of edited faces. An “investment game” showed that the UV penetrated even more deeply to influence subjects’ implicit decisions concerning robots’ social trustworthiness, and that these fundamental social decisions depend on subtle cues of facial expression that are also used to judge humans. Preliminary evidence suggests category confusion may occur in the UV but does not mediate the likability effect. These findings suggest that while classic elements of human social psychology govern human–robot social interaction, robust UV effects pose a formidable android-specific problem.

The unknowns of cognitive enhancement

Martha Farah points out how little is known about current methods of cognitive enhancement, and suggests several reasons why we are so ignorant. A few clips from her article:

...stimulants such as amphetamine and methylphenidate (sold under trade names such as Adderall and Ritalin, respectively) are widely used for nonmedical reasons …cognitive enhancement with stimulants is commonplace on college campuses…use by college faculty and other professionals to enhance workplace productivity has been documented…The published literature includes substantially different estimates of the effectiveness of prescription stimulants as cognitive enhancers. A recent meta-analysis suggests that the effect is most likely real but small for executive function tests stressing inhibitory control, and probably nonexistent for executive function tests stressing working memory.

Farah notes several studies suggesting that the effects of Adderall and another drug, modafinil (trade name Provigil) on ‘cognitive enhancement’ are actually effects on task motivation and mood.

The newest trend in cognitive enhancement is the use of transcranial electric stimulation. In the most widely used form, called transcranial direct current stimulation (tDCS), a weak current flows between an anode and a cathode placed on the head, altering the resting potential of neurons in the current's path….Transcranial electric stimulation is expanding …with new companies selling compact, visually appealing, user-friendly devices…published literature includes a mix of findings. One recent attempt to synthesize the literature with meta-analysis concluded that tDCS has no effect whatsoever on a wide range of cognitive abilities.

Why are we so ignorant about cognitive enhancement? Several factors seem to be at play. The majority of studies on enhancement effectiveness have been carried out on small samples, rarely more than 50 subjects, which limits their power. Furthermore, cognitive tasks typically lend themselves to a variety of different but reasonable outcome measures, such as overall errors, specific types of errors (for example, false alarms), and response times. In addition, there is usually more than one possible statistical approach to analyze the enhancement effect. Small samples and flexibility in design and analysis raise the likelihood of published false positives. In addition, pharmacologic and electric enhancements may differ in effectiveness depending on the biological and psychological traits of the user, which complicates the effort to understand the true enhancement potential of these technologies. Industry is understandably unmotivated to take on the expense of appropriate large-scale trials of enhancement, given that the stimulants used are illegally diverted and transcranial electric stimulation devices can be sold without such evidence. The inferential step from laboratory effect to real-world benefit adds another layer of challenge. Given that enhancements would likely be used for years, long-term effectiveness and safety are essential concerns but are particularly difficult and costly to determine. As a result, the only large-scale trial we may see is the enormous but uncontrolled and poorly monitored trial of people using these drugs and devices on their own.

Can we really change our aging?

I thought I would point MindBlog readers to a brief talk I gave, "Can we really change our aging?," at the Nov. 1, 2015 meeting of the Fort Lauderdale Prime Timers, and a Nov. 7 Lunch and Learn session of SAGE South Florida. It distills the contents of about 250 MindBlog posts I’ve written describing research on aging, and passes on some of the facts I think are most striking.

Critical period for visual pathway formation? - another dogma bites the dust.

India, which may have the largest number of blind children in the world, with estimates ranging from 360,000 to nearly 1.2 million, is providing a vast laboratory that has overturned one of the central dogmas of brain development - that development of visual (and other) pathways must take place within a critical time window, after which formation of proper connections becomes much more difficult or impossible. Until recently, children over 8 years old with congenital cataracts were not considered appropriate subjects for lens replacement surgery. In Science Magazine Rhitu Chatterjee describes a project begun in 2004, Led by neuroscientist Pawan Sinha, that has restored sight to much older children. The story of one 18-year old is followed, who over the 18 months following lens replacement begin to see with clarity that permitted him to bike through a crowded marketplace.

Of the nearly 500 children and young adults that have undergone cataract operation, about half became research subjects. One fascinating result that emerged is that visual experience isn't critical for certain visual function, the brain seems to be prewired, for example, to be fooled by some visual illusions that were thought to be a product of learning. One is the Ponzo illusion, which typically involves lines converging on the horizon (like train tracks) and two short parallel lines cutting across them. Although the horizontal lines are identical, the one nearer the horizon looks longer. If the Ponzo illusion were the result of visual learning, newly sighted kids wouldn't fall for it. But in fact, children who had just had their vision restored were just as susceptible to the Ponzo illusion as were control subjects with normal vision. The kids also fell for the Müller-Lyer illusion, a pair of lines with arrowheads on both ends; one set of arrowheads points outward, the other inward toward the line. The line with the inward arrowheads seems longer. These results lead Sinha to suggest that the illusion is being driven by very simple factors in the image that the brain is probably innately programmed to respond to.

A biomarker for early detection of dementia

Kunz et al. show that in an at-risk group for developing Alzheimer's different brain signals are detected many decades before onset of the disease. Individuals showing this change would be candidates for starting therapy at early stages of the disease.

Alzheimer’s disease (AD) manifests with memory loss and spatial disorientation. AD pathology starts in the entorhinal cortex, making it likely that local neural correlates of spatial navigation, particularly grid cells, are impaired. Grid-cell–like representations in humans can be measured using functional magnetic resonance imaging. We found that young adults at genetic risk for AD (APOE-ε4 carriers) exhibit reduced grid-cell–like representations and altered navigational behavior in a virtual arena. Both changes were associated with impaired spatial memory performance. Reduced grid-cell–like representations were also related to increased hippocampal activity, potentially reflecting compensatory mechanisms that prevent overt spatial memory impairment in APOE-ε4 carriers. Our results provide evidence of behaviorally relevant entorhinal dysfunction in humans at genetic risk for AD, decades before potential disease onset.

Lifting weights and the brain.

Reynolds points to a study suggesting that light weight training slows down the shrinkage and tattering of our brain's white matter (nerve tracts) that normally occurs with aging. And, from the New Yorker:

Brain Pickings on 'the most important things'

I enjoy the weekly email sent out by Maria Popova's Brain Pickings website. I find it a bit overwhelming (and high on the estrogens), and so sample only a few of the idea chunks it presents. I suggest you have a look. On its 9th birthday, Brain Pickings noted the "9 most important things I have learned":

1.  Allow yourself the uncomfortable luxury of changing your mind.
2.  Do nothing for prestige or status or money or approval alone.
3. Be generous.
4. Build pockets of stillness into your life.
5. When people try to tell you who you are, don’t believe them.
6. Presence is far more intricate and rewarding an art than productivity.
7. Expect anything worthwhile to take a long time.
8. Seek out what magnifies your spirit.
9. Don’t be afraid to be an idealist.

A lab experiment: visibility of wealth increases wealth inequality

Nishi et al. do a fascinating laboratory experiment conducted online showing that when people can see wealth inequality in their social network, this propels further inequality through reduced cooperation and reduced social connectivity. From a summary by Gächter

Nishi and colleagues' experimental model used an assessment of people's willingness to contribute to public goods to test how initial wealth inequality and the structure of the social network influence the evolution of inequality...can mere observation of your neighbour's wealth lead to more inequality over time, even if such information does not change economic incentives? Visible wealth might have a psychological effect by triggering social comparisons and thereby influencing economic choices that have repercussions for inequality.

...the researchers endowed all participants with tokens, worth real money...in a treatment without inequality, all participants initially received the same number of tokens; in a low-inequality treatment, participants had similar but different initial endowments; and in the high-inequality treatment there was a substantial starting difference between participants...A crucial manipulation in this experiment was wealth visibility. Under invisible conditions, the participants could observe only their own accumulated wealth. Under visibility, they could see the accumulated wealth of their connected neighbours but not the whole network....

The groups typically comprised 17 people arranged at random in a social network in which, on average, about 5 people were linked ('neighbours'). In each of the 10 rounds of the following game, participants had to decide whether to behave pro-socially ('cooperate') by reducing their own wealth by 50 tokens per connected neighbour to benefit each of them by 100 tokens, or to behave pro-selfishly ('defect') by keeping their tokens for themselves. These decisions had consequences for accumulated wealth levels and inequality. At the end of each round, the subjects learnt whether their neighbours had cooperated or defected and 30% of participants were given the opportunity to change their neighbour, that is, to either sever an existing link or to create a new one.

The authors find that, under high initial wealth inequality, visibility of neighbours' accumulated wealth increases inequality over time relative to the invisibility condition.

Here is the abstract from Nishi et al.:

Humans prefer relatively equal distributions of resources, yet societies have varying degrees of economic inequality. To investigate some of the possible determinants and consequences of inequality, here we perform experiments involving a networked public goods game in which subjects interact and gain or lose wealth. Subjects (n = 1,462) were randomly assigned to have higher or lower initial endowments, and were embedded within social networks with three levels of economic inequality (Gini coefficient = 0.0, 0.2, and 0.4). In addition, we manipulated the visibility of the wealth of network neighbours. We show that wealth visibility facilitates the downstream consequences of initial inequality—in initially more unequal situations, wealth visibility leads to greater inequality than when wealth is invisible. This result reflects a heterogeneous response to visibility in richer versus poorer subjects. We also find that making wealth visible has adverse welfare consequences, yielding lower levels of overall cooperation, inter-connectedness, and wealth. High initial levels of economic inequality alone, however, have relatively few deleterious welfare effects.

More exercise correlates with younger body cells.

Reynolds points to work by Loprinzi et al. showing physicaly active people have longer telomeres at the end of their chromosomes' DNA strands than sedentary people. (A telomere is a region of repetitive nucleotide sequences at each end of a chromatid, which protects the end of the chromosome from deterioration from from fusion with neighboring chromosomes. It's length is a measure of a cell's biological age because it naturally shortens and frays with age.) Here is their abstract, complete with three (unnecessary) abbreviations, LTL (leukocyte telomere length), PA (physical activity) and MBB (movement based behaviors), that you will have to keep in your short term memory for a few seconds: 

INTRODUCTION: Short leukocyte telomere length (LTL) has become a hallmark characteristic of aging. Some, but not all, evidence suggests that physical activity (PA) may play an important role in attenuating age-related diseases and may provide a protective effect for telomeres. The purpose of this study was to examine the association between PA and LTL in a national sample of US adults from the National Health and Nutrition Examination Survey.  

METHODS: National Health and Nutrition Examination Survey data from 1999 to 2002 (n = 6503; 20-84 yr) were used. Four self-report questions related to movement-based behaviors (MBB) were assessed. The four MBB included whether individuals participated in moderate-intensity PA, vigorous-intensity PA, walking/cycling for transportation, and muscle-strengthening activities. An MBB index variable was created by summing the number of MBB an individual engaged in (range, 0-4).  

RESULTS: A clear dose-response relation was observed between MBB and LTL; across the LTL tertiles, respectively, the mean numbers of MBB were 1.18, 1.44, and 1.54 (Ptrend less than 0.001). After adjustments (including age) and compared with those engaging in 0 MBB, those engaging in 1, 2, 3, and 4 MBB, respectively, had a 3% (P = 0.84), 24% (P = 0.02), 29% (P = 0.04), and 52% (P = 0.004) reduced odds of being in the lowest (vs highest) tertile of LTL; MBB was not associated with being in the middle (vs highest) tertile of LTL.  

CONCLUSIONS: Greater engagement in MBB was associated with reduced odds of being in the lowest LTL tertile.