After Phrenology: Neural Reuse and the Interactive Brain

I've been reading through an interesting article by Michael Anderson, a précis of a book accepted for publication and available as a PDF through BBS. I pass on the abstract:

Neural reuse is a form of neuroplasticity whereby neural elements originally developed for one purpose are put to multiple uses. A diverse behavioral repertoire is achieved via the creation of multiple, nested, and overlapping neural coalitions, in which each neural element is a member of multiple different coalitions and cooperates with a different set of partners at different times. This has profound implications for how we think about our continuity with other species, for how we understand the similarities and differences between psychological processes, and for how best to pursue a unified science of the mind. After Phrenology surveys the terrain and advocates for a series of reforms in psychology and cognitive neuroscience. The book argues that, among other things, we should capture brain function in a multi-dimensional manner, develop a new, action-oriented vocabulary for psychology, and recognize that higher-order cognitive processes are built from complex configurations of already evolved circuitry.

Neural basis of anxiety reduction by placebo.

Meyer et al. directly measure neural consequences of expecting a placebo treatment to be effective in relieving anxiety:

The beneficial effects of placebo treatments on fear and anxiety (placebo anxiolysis) are well known from clinical practice, and there is strong evidence indicating a contribution of treatment expectations to the efficacy of anxiolytic drugs. Although clinically highly relevant, the neural mechanisms underlying placebo anxiolysis are poorly understood. In two studies in humans, we tested whether the administration of an inactive treatment along with verbal suggestions of anxiolysis can attenuate experimentally induced states of phasic fear and/or sustained anxiety. Phasic fear is the response to a well defined threat and includes attentional focusing on the source of threat and concomitant phasic increases of autonomic arousal, whereas in sustained states of anxiety potential and unclear danger requires vigilant scanning of the environment and elevated tonic arousal levels. Our placebo manipulation consistently reduced vigilance measured in terms of undifferentiated reactivity to salient cues (indexed by subjective ratings, skin conductance responses and EEG event-related potentials) and tonic arousal [indexed by cue-unrelated skin conductance levels and enhanced EEG alpha (8–12 Hz) activity], indicating a downregulation of sustained anxiety rather than phasic fear. We also observed a placebo-dependent sustained increase of frontal midline EEG theta (4–7 Hz) power and frontoposterior theta coupling, suggesting the recruitment of frontally based cognitive control functions. Our results thus support the crucial role of treatment expectations in placebo anxiolysis and provide insight into the underlying neural mechanisms.

How alarm amplifies through social networks.

We've all probably played the parlor game with 10 or more people sitting in a circle, with one whispering a word into the ear of the person to their right, continuing to pass the word by whispering to the right until it comes back to the originator, frequently altered from its original form. Moussaïd et al. do a version of this routine in an experiment on how risk perception of hazardous events such as contagious outbreaks, terrorist attacks, and climate change spread through social networks. They find that although the content of a message is gradually lost over repeated social transmissions, subjective perceptions of risk propagate and amplify due to social influence.

Understanding how people form and revise their perception of risk is central to designing efficient risk communication methods, eliciting risk awareness, and avoiding unnecessary anxiety among the public. However, public responses to hazardous events such as climate change, contagious outbreaks, and terrorist threats are complex and difficult-to-anticipate phenomena. Although many psychological factors influencing risk perception have been identified in the past, it remains unclear how perceptions of risk change when propagated from one person to another and what impact the repeated social transmission of perceived risk has at the population scale. Here, we study the social dynamics of risk perception by analyzing how messages detailing the benefits and harms of a controversial antibacterial agent undergo change when passed from one person to the next in 10-subject experimental diffusion chains. Our analyses show that when messages are propagated through the diffusion chains, they tend to become shorter, gradually inaccurate, and increasingly dissimilar between chains. In contrast, the perception of risk is propagated with higher fidelity due to participants manipulating messages to fit their preconceptions, thereby influencing the judgments of subsequent participants. Computer simulations implementing this simple influence mechanism show that small judgment biases tend to become more extreme, even when the injected message contradicts preconceived risk judgments. Our results provide quantitative insights into the social amplification of risk perception, and can help policy makers better anticipate and manage the public response to emerging threats.

Modulating movement intention and the extended present with tDCS.

Douglas et al. do a fascinating bit of work on the 'extended present' in which our brains function, during which our experienced intention to make a movement actually comes ~200 milliseconds after motor cortex signals initiating the movement (the famous Libet experiment showing we are 'late to action'). Conscious intention, or volition, provides the foundation for our attributing agency to ourselves, and for society attributing responsibility to an individual. A distorted sense of volition is a hallmark of many neurological and psychiatric illnesses such as alien hand syndrome, psychogenic movement disorders, and schizophrenia.

Conscious intention is a fundamental aspect of the human experience. Despite long-standing interest in the basis and implications of intention, its underlying neurobiological mechanisms remain poorly understood. Using high-definition transcranial DC stimulation (tDCS), we observed that enhancing spontaneous neuronal excitability in both the angular gyrus and the primary motor cortex caused the reported time of conscious movement intention to be ∼60–70 ms earlier. Slow brain waves recorded ∼2–3 s before movement onset, as well as hundreds of milliseconds after movement onset, independently correlated with the modulation of conscious intention by brain stimulation. These brain activities together accounted for 81% of interindividual variability in the modulation of movement intention by brain stimulation. A computational model using coupled leaky integrator units with biophysically plausible assumptions about the effect of tDCS captured the effects of stimulation on both neural activity and behavior. These results reveal a temporally extended brain process underlying conscious movement intention that spans seconds around movement commencement.

Brain correlates of loving kindness meditation.

Garrison and collaborators extend their work on brain correlates of meditation practice, noting again a central role for the posterior cingulate cortex/precuneus (for previous posts in this thread, enter "Garrison" in the MindBlog search box in the left column).

Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as “may all beings be happy,” to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively novel approach, the intrinsic connectivity distribution of functional connectivity, to identify regions that differ in intrinsic connectivity between groups, and then used a data-driven approach to seed-based connectivity analysis to identify which connections differ between groups. Our findings suggest group differences in brain regions involved in self-related processing and mind wandering, emotional processing, inner speech, and memory. Meditators showed overall reduced BOLD signal and intrinsic connectivity during loving kindness as compared to novices, more specifically in the posterior cingulate cortex/precuneus (PCC/PCu), a finding that is consistent with our prior work and other recent neuroimaging studies of meditation. Furthermore, meditators showed greater functional connectivity during loving kindness between the PCC/PCu and the left inferior frontal gyrus, whereas novices showed greater functional connectivity during loving kindness between the PCC/PCu and other cortical midline regions of the default mode network, the bilateral posterior insula lobe, and the bilateral parahippocampus/hippocampus. These novel findings suggest that loving kindness meditation involves a present-centered, selfless focus for meditators as compared to novices.

Essentialism

I pass on some clips from Richard Dawkins' brief essay, and suggest you also take a look at Lisa Barrett's comments on essentialist views of the mind:

Essentialism—what I’ve called "the tyranny of the discontinuous mind"—stems from Plato, with his characteristically Greek geometer’s view of things. For Plato, a circle, or a right triangle, were ideal forms, definable mathematically but never realised in practice. A circle drawn in the sand was an imperfect approximation to the ideal Platonic circle hanging in some abstract space. That works for geometric shapes like circles, but essentialism has been applied to living things and Ernst Mayr blamed this for humanity’s late discovery of evolution—as late as the nineteenth century. If, like Aristotle, you treat all flesh-and-blood rabbits as imperfect approximations to an ideal Platonic rabbit, it won’t occur to you that rabbits might have evolved from a non-rabbit ancestor, and might evolve into a non-rabbit descendant. If you think, following the dictionary definition of essentialism, that the essence of rabbitness is "prior to" the existence of rabbits (whatever "prior to" might mean, and that’s a nonsense in itself) evolution is not an idea that will spring readily to your mind, and you may resist when somebody else suggests it.

Essentialism rears its ugly head in racial terminology. The majority of "African Americans" are of mixed race. Yet so entrenched is our essentialist mind-set, American official forms require everyone to tick one race/ethnicity box or another: no room for intermediates. A different but also pernicious point is that a person will be called "African American" even if only, say, one of his eight great grandparents was of African descent. As Lionel Tiger put it to me, we have here a reprehensible "contamination metaphor." But I mainly want to call attention to our society’s essentialist determination to dragoon a person into one discrete category or another. We seem ill-equipped to deal mentally with a continuous spectrum of intermediates. We are still infected with the plague of Plato’s essentialism.

Moral controversies such as those over abortion and euthanasia are riddled with the same infection. At what point is a brain-dead accident-victim defined as "dead"? At what moment during development does an embryo become a "person"? Only a mind infected with essentialism would ask such questions. An embryo develops gradually from single-celled zygote to newborn baby, and there’s no one instant when "personhood" should be deemed to have arrived. The world is divided into those who get this truth and those who wail, "But there has to be some moment when the fetus becomes human." No, there really doesn’t, any more than there has to be a day when a middle aged person becomes old. It would be better—though still not ideal—to say the embryo goes through stages of being a quarter human, half human, three quarters human . . . The essentialist mind will recoil from such language and accuse me of all manner of horrors for denying the essence of humanness...Our essentialist urge toward rigid definitions of "human" (in debates over abortion and animal rights) and "alive" (in debates over euthanasia and end-of-life decisions) makes no sense in the light of evolution and other gradualistic phenomena.

We define a poverty "line": you are either "above" or "below" it. But poverty is a continuum. Why not say, in dollar-equivalents, how poor you actually are? The preposterous Electoral College system in US presidential elections is another, and especially grievous, manifestation of essentialist thinking. Florida must go either wholly Republican or wholly Democrat—all 25 Electoral College votes—even though the popular vote is a dead heat. But states should not be seen as essentially red or blue: they are mixtures in various proportions.

You can surely think of many other examples of "the dead hand of Plato"—essentialism. It is scientifically confused and morally pernicious. It needs to be retired.

What to do with brain markers that predict future behaviors?

An interesting review from Gabrieli et al. suggesting how predicting individual futures with neuromarkers might make a pragmatic contribution to human welfare.

Neuroimaging has greatly enhanced the cognitive neuroscience understanding of the human brain and its variation across individuals (neurodiversity) in both health and disease. Such progress has not yet, however, propelled changes in educational or medical practices that improve people’s lives. We review neuroimaging findings in which initial brain measures (neuromarkers) are correlated with or predict future education, learning, and performance in children and adults; criminality; health-related behaviors; and responses to pharmacological or behavioral treatments. Neuromarkers often provide better predictions (neuroprognosis), alone or in combination with other measures, than traditional behavioral measures. With further advances in study designs and analyses, neuromarkers may offer opportunities to personalize educational and clinical practices that lead to better outcomes for people.

Figure - Functional Brain Measure Predicting a Clinical Outcome: Prior to treatment, patients with social anxiety disorder who exhibited greater posterior activation (left) for angry relative to neutral facial expressions had a better clinical response to CBT (cognitive behavioral therapy) than patients who exhibited lesser activation (right)

More comment on anti-aging regimes

A recent brief review by Jane Brodie points to work showing a small effect of cognitive training programs engaging memory, reasoning, or speed of processing. After 10 years 60% of those in the training programs, compared with 50 percent of the controls, had maintained or improved their ability to perform activities of daily living. Reasoning and speed, but not memory, training resulted in improved targeted cognitive abilities for 10 years. The article also contains a brief video demonstrating the NeuroRacer program developed by Gazzaley and colleagues. The article points out that very few of the potions and gizmos on the market "...have been proven to have a meaningful, sustainable benefit beyond lining the pockets of their sellers. Before you invest in them, you’d be wise to look for well-designed, placebo-controlled studies that attest to their ability to promote a youthful memory and other cognitive functions."

Grasp posture of our hands biases our visual processing.

Fascinating observations from Laura Thomas:

Observers experience biases in visual processing for objects within easy reach of their hands; these biases may assist them in evaluating items that are candidates for action. I investigated the hypothesis that hand postures that afford different types of actions differentially bias vision. Across three experiments, participants performed global-motion-detection and global-form-perception tasks while their hands were positioned (a) near the display in a posture affording a power grasp, (b) near the display in a posture affording a precision grasp, or (c) in their laps. Although the power-grasp posture facilitated performance on the motion-detection task, the precision-grasp posture instead facilitated performance on the form-perception task. These results suggest that the visual system weights processing on the basis of an observer’s current affordances for specific actions: Fast and forceful power grasps enhance temporal sensitivity, whereas detail-oriented precision grasps enhance spatial sensitivity.

The sound of climate change.

The sound of climate change from the Amazon to the Arctic from Ensia on Vimeo.

Literary (like musical and athletic) expertise shifts brain activity to the caudate nucleus.

Erhard et al. find that creative writing by expert versus amateur writers is associated with more activation in the caudate nucleus, the same area that become more active in expert versus amateur athletes and musicians. The increased recruitment of the basal ganglia network with increasing levels of expertise correlates with behavioral automatization that facilitates complex cognitive tasks.

The aim of the present study was to explore brain activities associated with creativity and expertise in literary writing. Using functional magnetic resonance imaging (fMRI), we applied a real-life neuroscientific setting that consisted of different writing phases (brainstorming and creative writing; reading and copying as control conditions) to well-selected expert writers and to an inexperienced control group.

During creative writing, experts showed cerebral activation in a predominantly left-hemispheric fronto-parieto-temporal network. When compared to inexperienced writers, experts showed increased left caudate nucleus and left dorsolateral and superior medial prefrontal cortex activation. In contrast, less experienced participants recruited increasingly bilateral visual areas. During creative writing activation in the right cuneus showed positive association with the creativity index in expert writers.

High experience in creative writing seems to be associated with a network of prefrontal (mPFC and DLPFC) and basal ganglia (caudate) activation. In addition, our findings suggest that high verbal creativity specific to literary writing increases activation in the right cuneus associated with increased resources obtained for reading processes.

Human Purpose

The recent NYTimes David Brooks Op-Ed piece “What is your purpose?” has drawn a lot of feedback and comment. He laments the passing the era of lofty authority figures like Reinhold Niebuhr who argued for a coherent moral ecology. (I remember as a Quincy House Harvard undergraduate in 1962 having breakfast with Reinhold and Ursula Niebuhr during their several weeks residence in the house.)

These days we live in a culture that is more diverse, decentralized, interactive and democratized…Public debate is now undermoralized and overpoliticized…Intellectual prestige has drifted away from theologians, poets and philosophers and toward neuroscientists, economists, evolutionary biologists and big data analysts. These scholars have a lot of knowledge to bring, but they’re not in the business of offering wisdom on the ultimate questions.

And there you have it. Per Thomas Wolfe, “You Can’t Go Home Again.” Brooks’ "neuroscientists, economists, evolutionary biologists and big data analysts" have let the genie out of the bottle. We are very clear now that “purpose” is a human invention in the service of passing on our genes. I have seen no more clear statement on purpose than that given by E. O. Wilson, which I excerpted in my Dec. 5, 2014 post.

Trust and the Insula

From Belfi et al:

Reciprocal trust is a crucial component of cooperative, mutually beneficial social relationships. Previous research using tasks that require judging and developing interpersonal trust has suggested that the insula may be an important brain region underlying these processes. Here, using a neuropsychological approach, we investigated the role of the insula in reciprocal trust during the Trust Game (TG), an interpersonal economic exchange. Consistent with previous research, we found that neurologically normal adults reciprocate trust in kind, i.e., they increase trust in response to increases from their partners, and decrease trust in response to decreases. In contrast, individuals with damage to the insula displayed abnormal expressions of trust. Specifically, these individuals behaved benevolently (expressing misplaced trust) when playing the role of investor, and malevolently (violating their partner's trust) when playing the role of the trustee. Our findings lend further support to the idea that the insula is important for expressing normal interpersonal trust, perhaps because the insula helps to recognize risk during decision-making and to identify social norm violations.

The immensity of the vacated present.

The title of this post is a phrase from a recent essay by Vivian Gornick, "The cost of daydreaming," describing an experience that very much resonates with my own, and that I think is describing her discovery and way of noticing the distinction between our internal mind wandering (default mode) and present centered outwardly oriented (attentional) brain networks (the subject of many MindBlog posts). On finding that she could sense the start of daydreaming and suppress it:

...the really strange and interesting thing happened. A vast emptiness began to open up behind my eyes as I went about my daily business. The daydreaming, it seemed, had occupied more space than I’d ever imagined. It was as though a majority of my waking time had routinely been taken up with fantasizing, only a narrow portion of consciousness concentrated on the here and now...I began to realize what daydreaming had done for me — and to me.

Turning 60 was like being told I had six months to live. Overnight, retreating into the refuge of a fantasized tomorrow became a thing of the past. Now there was only the immensity of the vacated present...It wasn’t hard to cut short the daydreaming, but how exactly did one manage to occupy the present when for so many years one hadn’t?"

Then, after a period of time:

...I became aware, after a street encounter, that the vacancy within was stirring with movement. A week later another encounter left me feeling curiously enlivened. It was the third one that did it. A hilarious exchange had taken place between me and a pizza deliveryman, and sentences from it now started repeating themselves in my head as I walked on, making me laugh each time anew, and each time with yet deeper satisfaction. Energy — coarse and rich — began to swell inside the cavity of my chest. Time quickened, the air glowed, the colors of the day grew vivid; my mouth felt fresh. A surprising tenderness pressed against my heart with such strength it seemed very nearly like joy; and with unexpected sharpness I became alert not to the meaning but to the astonishment of human existence. It was there on the street, I realized, that I was filling my skin, occupying the present.

Yet another self therapy electrical widget.

I've done a number of posts on transcranial direct current stimulation (tDCS). Entering 'transcranial' in MindBlog's search box takes you to posts on tDCS effects on impulse control, memory enhancement, general cognition, etc. Entering tDCS in a google search box gets you a plethora of offered devices costing from $50 to $300+. An article by Kira Peikoff now points to a forthcoming new-agey device called Thync that is claimed to alter your mood as desired ("calm vibes" or "energy vibes"). An interesting clip from that article:

In January, the journal Brain Stimulation published the largest meta-analysis of tDCS to date. After examining every finding replicated by at least two research groups, leading to 59 analyses, the authors reported that one session of tDCS failed to show any significant benefit for users.

Thync developers claim to be bypassing the brain and using pulsed currents to stimulate subcutaneous peripheral nerves to modulate the stress response. The placebo-controlled studies they say they have done to document effectiveness of the procedure have not been published.

Observing brain correlates of social interactions.

Bilek et al. look at coordinated brain activity during social interactions between two people in a joint attention paradigm, using a hyperscanning procedure in which neuroimaging is done with the subjects' brain activity measured in two scanner sites coupled over the internet. Allowing two humans to see (and possibly hear) each other in a hyperscanning framework makes possible an immersive social interaction while both participant’s brains are imaged. The authors constructed a setup with delay-free data transmission and precisely synchronized data acquisition, in addition to a live video stream provided between scanner sites during the sessions. From their significance and abstract sections:

Social interaction is the likely driver of human brain evolution, critical for health, and underlies phenomena as varied as childhood development, stock market behavior, and much of what is studied in the humanities. However, appropriate experimental methods to study the underlying brain processes are still developing and technically challenging...Here, we used hyperscanning functional MRI (fMRI) to study information flow between brains of human dyads during real-time social interaction in a joint attention paradigm. In a hardware setup enabling immersive audiovisual interaction of subjects in linked fMRI scanners, we characterize cross-brain connectivity components that are unique to interacting individuals, identifying information flow between the sender’s and receiver’s temporoparietal junction. We replicate these findings in an independent sample and validate our methods by demonstrating that cross-brain connectivity relates to a key real-world measure of social behavior. Together, our findings support a central role of human-specific cortical areas in the brain dynamics of dyadic interactions and provide an approach for the noninvasive examination of the neural basis of healthy and disturbed human social behavior with minimal a priori assumptions.

Figure: Neural coupling of sender and receiver right temporoparietal junctions in a shared attention paradigm. A, Discovery study performed on 26 subjects (13 pairs); B, Replication study performed on 50 subjects (25 pairs).

Early environment and stress systems in children.

Most of the detailed work on the long term effects of adverse early life environment on stress response systems has been done with rodent models. McLaughlin et al. now present results from the Bucharest Early Intervention Project examining whether randomized placement of children into a family caregiving environment alters development of the autonomic nervous system and HPA axis in children exposed to early-life deprivation associated with institutional rearing. They provide the first experimental evidence in humans for a sensitive period with regard to stress response system development.

Disruptions in stress response system functioning are thought to be a central mechanism by which exposure to adverse early-life environments influences human development. Although early-life adversity results in hyperreactivity of the sympathetic nervous system (SNS) and hypothalamic–pituitary–adrenal (HPA) axis in rodents, evidence from human studies is inconsistent. We present results from the Bucharest Early Intervention Project examining whether randomized placement into a family caregiving environment alters development of the autonomic nervous system and HPA axis in children exposed to early-life deprivation associated with institutional rearing. Electrocardiogram, impedance cardiograph, and neuroendocrine data were collected during laboratory-based challenge tasks from children (mean age = 12.9 y) raised in deprived institutional settings in Romania randomized to a high-quality foster care intervention (n = 48) or to remain in care as usual (n = 43) and a sample of typically developing Romanian children (n = 47). Children who remained in institutional care exhibited significantly blunted SNS and HPA axis responses to psychosocial stress compared with children randomized to foster care, whose stress responses approximated those of typically developing children. Intervention effects were evident for cortisol and parasympathetic nervous system reactivity only among children placed in foster care before age 24 and 18 months, respectively, providing experimental evidence of a sensitive period in humans during which the environment is particularly likely to alter stress response system development. We provide evidence for a causal link between the early caregiving environment and stress response system reactivity in humans with effects that differ markedly from those observed in rodent models.

Cognitive training enhances intrinsic brain connectivity in childhood.

A fascinating open access article from Astle et al., who found changes in brain connectivity in 8-11 year old children who completed 20 sessions of computerized working memory training at home:

In human participants, the intensive practice of particular cognitive activities can induce sustained improvements in cognitive performance, which in some cases transfer to benefits on untrained activities. Despite the growing body of research examining the behavioral effects of cognitive training in children, no studies have explored directly the neural basis of these training effects in a systematic, controlled fashion. Therefore, the impact of training on brain neurophysiology in childhood, and the mechanisms by which benefits may be achieved, are unknown. Here, we apply new methods to examine dynamic neurophysiological connectivity in the context of a randomized trial of adaptive working memory training undertaken in children. After training, connectivity between frontoparietal networks and both lateral occipital complex and inferior temporal cortex was altered. Furthermore, improvements in working memory after training were associated with increased strength of neural connectivity at rest, with the magnitude of these specific neurophysiological changes being mirrored by individual gains in untrained working memory performance.

Ideology distorts perception of social mobility in the U.S.

I find it interesting that I share the same misperception of social mobility changes that are noted in this piece of work by Chambers et al.:

The ability to move upward in social class or economic position (i.e., social mobility) is a defining feature of the American Dream, yet recent public-opinion polls indicate that many Americans are losing confidence in the essential fairness of the system and their opportunities for financial advancement. In two studies, we examined Americans’ perceptions of both current levels of mobility in the United States and temporal trends in mobility, and we compared these perceptions with objective indicators to determine perceptual accuracy. Overall, participants underestimated current mobility and erroneously concluded that mobility has declined over the past four decades. These misperceptions were more pronounced among politically liberal participants than among politically moderate or conservative ones. These perception differences were accounted for by liberals’ relative dissatisfaction with the current social system, social hierarchies, and economic inequality. These findings have important implications for theories of political ideology.

The author's introduction, after noting pessimistic views on social mobility - "A recent Gallup poll (Dugan & Newport, 2013) found that only 52% of Americans agreed that there is plenty of opportunity for the average person to get ahead in life—down from 81% a mere 15 years earlier and the lowest level in over six decades." - points to the actual data on social mobility changes:

The publication of a recent, multidecade report provided us with an opportunity to compare those public perceptions with economic reality. Chetty, Hendren, Kline, Saez, and Turner (2014a, 2014b) compared the tax records of nearly 40 million American adults with those of their parents 20 years earlier, assessing changes in individuals’ economic position relative to their starting point in life (i.e., their parents’ economic position). They also compared individuals born in different decades, from the early 1970s through the mid 1990s, to assess any generational changes in mobility patterns. First, they found (as have Hertz, 2007; Lee & Solon, 2009) that intergenerational mobility rates have not declined, but in fact remained stable during the three-decade period they examined—contrary to popular belief (Dugan & Newport, 2013; Pew Research Center, 2012). Second, their data revealed that Americans enjoy—depending on one’s perspective—a substantial amount of social mobility. For example, of individuals born to parents in the bottom third of the income distribution (i.e., lower-class parents), 49% remained in the bottom third later in life, whereas 51% moved up to the middle or top third. In other words, despite their disadvantaged backgrounds, half of them were upwardly mobile (though still below the two-thirds one might expect based on the American Dream). Moreover, because they utilized much larger sample sizes, actual tax records (instead of self-reported income), and multiple indicators of mobility (e.g., incomes, college attendance rates), Chetty and colleagues’ study yields more precise estimates of social mobility than prior studies, and their findings are consistent with those of other published reports (Pew Research Center, 2013; U.S. Department of the Treasury, 2007). This makes their study the most appropriate standard to gauge our participants’ perceptual accuracy.

Economic origins of ultrasociality

Gowdy and Krall, in a manuscript under review by Behavioral and Brain Sciences, argue that the transition to agriculture in ants, termites, and our humans species generated the need for the extreme role specializations and ultrasociality that distinguish us from social species that depend on foraging for food. (Interested readers can obtain a copy of the MS from me).  I pass on a clip from the introduction, followed by their abstract.

With the widespread adoption of agriculture some 10,000 years ago human societies took on some important characteristics shared with social insects—ants and termites in particular—that also engage in the production of their own food. These characteristics represented a sharp break in the evolutionary history of these lineages and led to two important outcomes (1) ecosystem domination as a product of a dramatic increase in population size and much more intensive resource exploitation and (2) the suppression of individual autonomy as the group itself became the focus of economic organization. The evolution of agriculture in fungus-growing ants and termites, and in human societies, is an example of convergent evolution—the independent evolution of similar characteristics in species not closely related. In terms of genetics, ants, humans and termites could hardly be more different. Yet in all three lineages similar patterns of economic organization emerge through similar selection pressures. We use the term ultrasociality to refer to these lineages and we address the question of its origin through the fundamental question of evolutionary biology: “where did something come from and what were the selection pressures that favored its spread?”

Abstract:

Ultrasociality refers to the social organization of a few species, including humans and some social insects, having complex division of labor, city states and an almost exclusive dependence on agriculture for subsistence. We argue that the driving forces in the evolution of these ultrasocial societies were economic. With the agricultural transition, species could directly produce their own food and this was such a competitive advantage that those species now dominate the planet. Once underway, this transition was propelled by the selection of withinspecies groups that could best capture the advantages of (1) actively managing the inputs to food production, (2) a more complex division of labor, and (3) increasing returns to larger scale and larger group size. Together these factors reoriented productive life and radically altered the structure of these societies. Once agriculture began, populations expanded as these economic drivers opened up new opportunities for the exploitation of resources and the active management of inputs to food production. With intensified group-level competition, larger populations and intensive resource exploitation became competitive advantages and the “social conquest of earth” was underway. Ultrasocial species came to dominate the earth’s ecosystems. Ultrasociality also brought a loss of autonomy for individuals within the group. We argue that exploring the common causes and consequences of ultrasociality in humans and the social insects that adopted agriculture can provide fruitful insights into the evolution of complex human society.