Machiavellism, social dominance orientation and authoritarianism are tightly related (and subclinically psycopathic)

Depending on one’s ideology this may seem either obvious or counterintuitive but that is what a powerful set of five successive studies has found.

Laura Niemi & Liane Young, Caring across Boundaries versus Keeping Boundaries Intact: Links between Moral Values and Interpersonal Orientations. PLoS ONE 2013. Open access → LINK [doi:10.1371/journal.pone.0081605]

Abstract

Prior work has established robust diversity in the extent to which different moral values are endorsed. Some people focus on values related to caring and fairness, whereas others assign additional moral weight to ingroup loyalty, respect for authority and established hierarchies, and purity concerns. Five studies explore associations between endorsement of distinct moral values and a suite of interpersonal orientations: Machiavellianism, prosocial resource distribution, Social Dominance Orientation, and reported likelihood of helping and not helping kin and close friends versus acquaintances and neighbors. We found that Machiavellianism (Studies 1, 3, 4, 5) (e.g., amorality, controlling and status-seeking behaviors) and Social Dominance Orientation (Study 4) were negatively associated with caring values, and positively associated with valuation of authority. Those higher in caring values were more likely to choose prosocial resource distributions (Studies 2, 3, 4) and to report reduced likelihood of failing to help kin/close friends or acquaintances (Study 4). Finally, greater likelihood of helping acquaintances was positively associated with all moral values tested except authority values (Study 4). The current work offers a novel approach to characterizing moral values and reveals a striking divergence between two kinds of moral values in particular: caring values and authority values. Caring values were positively linked with prosociality and negatively associated with Machiavellianism, whereas authority values were positively associated with Machiavellianism and Social Dominance Orientation.

A synthesis of the results of the five studies is presented in figure 2:

Figure 2. Summary of correlations observed across all studies. Each square represents an observation of a significant partial correlation (politics, religion, and gender controlled). Each circle represents an observation of a significant zero-order correlation. Study (#) indicated on each circle/square. Moral values are color-coded.

“Mach” means Machiavellianism and “SDO” means social dominance orientation, which are clearly and positively correlated among them, via the same set of “group values” (ingroup loyalty, authority and purity). Instead helping those close to oneself and prosocial distribution are very positively correlated among them and associated with the “humanist values” or caring and fairness.

This is very much counterintuitive, especially as the authors use the term “individualizing” for the caring and fairness values, which makes absolutely no sense to me, as individualism means selfishness and aloofness, even misanthropy. Hence I replaced that term for “humanist” although I also pondered “personalist” (as the person can be something more whole and socially connected than the individual).

The produce of the two sets of values is even more at odds with the concept individualism. In fact it is the group (or “binding and dividing”) value people who actually strive for social dominance and favor Machiavellianism. This is because they do not think in the group as extensive but as intensive and almost certainly as tool for their own individualist selfish goals. 

Interestingly:

Most interpersonal behavior requires individuals to balance selfish motivation with prosocial motivation – to be a positive social partner who helps other people. These orientations are not mutually exclusive – care for the self is at times necessary to enable care for others. However, for some individuals, a motivation to dominate or exploit the group for selfish aims, measureable as Machiavellianism [20] or Social Dominance Orientation [21], may take precedence. Individuals high in Machiavellianism (“Machs”) admit to employing manipulation and deception to achieve power, status, control, and financial success [20]. These goals require successful management of group relations, which may in turn shed light on the paradoxical nature of Machiavellianism. Machs are often described as socially skilled, well-liked, popular, and excellent at building alliances [22], but they are also subclinically psychopathic [23] and exploitative of others’ trust [24], [25]. Machiavellian negotiation of relationships and social structures for personal gain may benefit from a moral stance that elevates values like loyalty and deference to authority. More specifically, these values are critical for the preservation of existing social order but largely insensitive to concerns about caring and fairness. Moralization of these values – alongside relative indifference to caring and fairness values – could facilitate strategic hierarchy management while freeing the individual to feel morally justified in engaging in manipulative or exploitative behavior.

Subclinically psychopathic is a most revealing concept. I have often though of this as a real social problem of first order. The subclinicality may only be because psychiatry has established a boundary not to touch the powerful, what would be playing with fire. But, as we will see below, there is more to it.

What happens with social dominance orientation?

Relatedly, Social Dominance Orientation (SDO) is characterized by a desire for inequality and a tendency to categorize people along a hierarchical “superior-inferior dimension” [21]. SDO, like Machiavellianism, has been found to predict various antisocial outcomes, including explicit racism and sexism as well as reduced empathy and concern for others [21], [26], [27]. While SDO has previously been identified as negatively correlated with individualizing values and positively correlated with binding values [2], SDO has not yet received attention for its potential positive connection with binding values when political orientation is controlled. Since an orientation towards social dominance requires a strict hierarchical worldview, a positive correlation between SDO and authority values, regardless of political orientation, would be predicted [2].

Later in the discussion they turn back to “Machs”:

What could account for the positive relationship between respect for authority and Machiavellianism, an antisocial interpersonal style associated with strategic manipulation? Indeed, Machs have been shown to lie more convincingly [35], steal more readily [36], and rationalize deeds with callous unemotionality [37]. To provide the foundation for two potential explanations for this surprising relationship, we first describe two relevant aspects of Machiavellianism: (1) Machiavellianism and psychopathy are distinct in relation to social norm processing, and (2) Machs are likely to be dominant individuals in positions of authority. Next, we propose two potential explanations for the positive relationships between moral valuation of respect for authority and Machiavellianism: (1) Machiavellianism may entail moralization of respect for authority for a variety of strategic reasons, and (2) authority values may license Machiavellian behavior.

Discussing the subtle differences between Machiavellianism and outright psychopathy:

Although Machiavellianism is characterized by selfishness and shares some overlap with psychopathy [23], Machs are not necessarily aloof and unconcerned with social norms. Instead, the ability to manipulate others may actually benefit from a keen sensitivity to norms that govern social structure.

Instead most clinical psychopaths tend to be aloof. 

Another key difference is that Machs are highly sensitive to punishment, while again true psychopaths may be somewhat indifferent to this social corrector, so Machs retreat and even give away profusely in order to avoid this outcome.

Machiavellianism is also clearly related to dominance and control and, therefore to respect for authority:

In addition to being hyper-attuned to social structure, Machs are also likely to reside at the top of those structures in positions of authority. Machiavellian-style social climbing tactics (e.g., manipulation and deception) are more likely to be used by individuals high in dominance and well-equipped to assume authority over others [38]. Likewise, Machiavellian supervisors in a range of business sectors have been described by subordinates as employing authoritarian work habits involving strict control over a hierarchical workplace structure [46]. As individuals who recognize they can personally benefit from “working the system” from a position of authority – rather than attempting to make the system work for all – Machs may be more likely to identify respect for authority as relevant or even central to their concepts of “right and wrong”.

Ironically Machiavellianism finds in authoritarianism a self-serving morality. Being able to play the game and climb to the top, Machs clearly benefit from such respect to authority themselves and will spread the word among their subordinates. It also helps themselves to self-regulate their behavior in ways that are within the boundaries of the game, yet still selfish. Accepting others’ authority acts as self-protection and gives them a moral varnish, internalizing these values allows them more easily to perform their flattery and igratiation climbing tactics (otherwise probably perceived as humiliation).

The authoritarian ethics seem also useful in order to condone otherwise anti-social behaviors such as cheating, graft or torture. Other recent studies have shown that individuals primed to feel high in power – that is, closer to “authority figure” status – were more likely to endorse unethical and antisocial behavior [55], [56].

Something I really miss in this study is the proportion of tendencies among the studied group, which could reflect general distribution in society. While the statistical correlations are systematically produced the proportion and intensity of the values of the actual human sample is not shown.

The authors assume that the prosocial values are generally desirable but in reality what I have found way too often is that many people, especially those in intermediate command positions or with a career to develop, experience serious contradictions between the “official” prosocial or humanist ethics and the “unofficial” but very real Machiavellian one. I would even say that they often feel emotionally broken by this contradiction. And this “they” at least sometimes becomes “we” and “I”, so painfully.

It would certainly be interesting to study this contradictory social and psychological reality, even cross-culturally. 

In any case this study does produce some very interesting data that should be most valuable for future and more comprehensive research. It also produces very important information for our meditations on our social and personal reality, and certainly it also applies to past realities, at least since society became complex and hierarchical.

 

Poverty directly damages brain development

Children that at early ages have similar or even greater gray matter than their wealthier peers, get stuck in a weaker development as they grow just for being poor. That is what a new study has found:

Jamie L. Hanson et al., Family Poverty Affects the Rate of Human Infant Brain Growth. PLoS ONE 2013. Open access → LINK [doi:10.1371/journal.pone.0080954]

Abstract


Living in poverty places children at very high risk for problems across a variety of domains, including schooling, behavioral regulation, and health. Aspects of cognitive functioning, such as information processing, may underlie these kinds of problems. How might poverty affect the brain functions underlying these cognitive processes? Here, we address this question by observing and analyzing repeated measures of brain development of young children between five months and four years of age from economically diverse backgrounds (n = 77). In doing so, we have the opportunity to observe changes in brain growth as children begin to experience the effects of poverty. These children underwent MRI scanning, with subjects completing between 1 and 7 scans longitudinally. Two hundred and three MRI scans were divided into different tissue types using a novel image processing algorithm specifically designed to analyze brain data from young infants. Total gray, white, and cerebral (summation of total gray and white matter) volumes were examined along with volumes of the frontal, parietal, temporal, and occipital lobes. Infants from low-income families had lower volumes of gray matter, tissue critical for processing of information and execution of actions. These differences were found for both the frontal and parietal lobes. No differences were detected in white matter, temporal lobe volumes, or occipital lobe volumes. In addition, differences in brain growth were found to vary with socioeconomic status (SES), with children from lower-income households having slower trajectories of growth during infancy and early childhood. Volumetric differences were associated with the emergence of disruptive behavioral problems.

Figure 2. This figure shows total gray matter volume for group by age.

The data is clear (for details of the localized frontal and parietal evolution see figs. 3 and 4). The question is: why does this happen? The paper attempts also to discuss that:

These results extend a consistent literature in rodents, non-human
primates, and humans suggesting that early environments marked by stress
or deprivation negatively influence brain development [65]–[69].
This emerging body of research has found differences in brain structure
in portions of the frontal lobe, which fits well with the analysis
presented here [68].
These findings suggest that aspects of low SES environments have
important functional implications for children’s health and adaptation [70],
perhaps by influencing key features of central nervous system
development. In regards to neurobiological mechanisms, the differences
in volume we find are likely due to neuronal remodeling, rather than
birth of new neurons (or neurogenesis) [27], [71], [72].

(…)


Candidate factors might include the effects of household resources,
environmental stimulation, crowding, exposure to pathogens and noise,
parental stress, and nutrition. It is also possible that pre-natal
experiences affect brain development and reflect other disadvantages and
risks related to poverty. Because humans are able to adapt to a range
of environmental conditions, we must understand more about the level at
which impoverished environments become toxic for children.

And quite suggestively in the introduction they mention as well that:

Conditions such as the variety and complexity of the stimuli in an
animal’s cage can influence different aspects of brain structure,
including the number of neurons, glial cells, myelination, dendrites,
synapses, and neurogenesis (for review, see Ref. [23]–[24]). 

The specific causes can be many but I’d dare say that “caging”, i.e. the limitation of stimuli for living in smaller, impoverished, artificial habitats (including of course whatever limitations that the adults around them may have, such as low culture or emotional instability) is likely to be a key negative environmental factor for brain development.

On the other hand I can imagine that certain enrichment (cultural, health even technological, why not?) that has happened to our species in general in the last centuries, may be behind the so-called Flynn effect, which is that the measured IQ has been growing everywhere quite steadily. 

But in any case it is quite worrying that these social differences have such a big effect on the children and emphasizes the need to overcome them and to provide the best possible environment for the development of the future generations.

 

Poverty: a peculiar type of stress that dramatically reduces cognitive function

An average of 13 IQ points. It’s not being poor what causes it but the stress of scarcity of resources, which simply copes the brain.

I reproduce the press release in full (with just some emphasis of my own) because of it’s great interest:

Poor concentration: Poverty reduces brainpower needed for navigating other areas of life

Poverty and all its related concerns require so much mental energy that the poor have less remaining brainpower to devote to other areas of life, according to research based at Princeton University. As a result, people of limited means are more likely to make mistakes and bad decisions that may be amplified by — and perpetuate — their financial woes.

Published in the journal Science, the study presents a unique perspective regarding the causes of persistent poverty. The researchers suggest that being poor may keep a person from concentrating on the very avenues that would lead them out of poverty. A person’s cognitive function is diminished by the constant and all-consuming effort of coping with the immediate effects of having little money, such as scrounging to pay bills and cut costs. Thusly, a person is left with fewer “mental resources” to focus on complicated, indirectly related matters such as education, job training and even managing their time.

In a series of experiments, the researchers found that pressing financial concerns had an immediate impact on the ability of low-income individuals to perform on common cognitive and logic tests. On average, a person preoccupied with money problems exhibited a drop in cognitive function similar to a 13-point dip in IQ, or the loss of an entire night’s sleep.

Research based at Princeton University found that poverty and all its related concerns require so much mental energy that the poor have less remaining brainpower to devote to other areas of life.

Experiments showed that the impact of financial concerns on the cognitive function of low-income individuals was similar to a 13-point dip in IQ, or the loss of an entire night’s sleep. To gauge the influence of poverty in natural contexts, the researchers tested 464 sugarcane farmers in India who rely on the annual harvest for at least 60 percent of their income. Each farmer performed better on common fluid-intelligence and cognition tests post-harvest compared to pre-harvest.

But when their concerns were benign, low-income individuals performed competently, at a similar level to people who were well off, said corresponding author Jiaying Zhao, who conducted the study as a doctoral student in the lab of co-author Eldar Shafir, Princeton’s William Stewart Tod Professor of Psychology and Public Affairs. Zhao and Shafir worked with Anandi Mani, an associate professor of economics at the University of Warwick in Britain, and Sendhil Mullainathan, a Harvard University economics professor.

“These pressures create a salient concern in the mind and draw mental resources to the problem itself. That means we are unable to focus on other things in life that need our attention,” said Zhao, who is now an assistant professor of psychology at the University of British Columbia.

“Previous views of poverty have blamed poverty on personal failings, or an environment that is not conducive to success,” she said. “We’re arguing that the lack of financial resources itself can lead to impaired cognitive function. The very condition of not having enough can actually be a cause of poverty.”

The mental tax that poverty can put on the brain is distinct from stress, Shafir explained. Stress is a person’s response to various outside pressures that — according to studies of arousal and performance — can actually enhance a person’s functioning, he said. In the Science study, Shafir and his colleagues instead describe an immediate rather than chronic preoccupation with limited resources that can be a detriment to unrelated yet still important tasks.

“Stress itself doesn’t predict that people can’t perform well — they may do better up to a point,” Shafir said. “A person in poverty might be at the high part of the performance curve when it comes to a specific task and, in fact, we show that they do well on the problem at hand. But they don’t have leftover bandwidth to devote to other tasks. The poor are often highly effective at focusing on and dealing with pressing problems. It’s the other tasks where they perform poorly.”

The fallout of neglecting other areas of life may loom larger for a person just scraping by, Shafir said. Late fees tacked on to a forgotten rent payment, a job lost because of poor time-management — these make a tight money situation worse. And as people get poorer, they tend to make difficult and often costly decisions that further perpetuate their hardship, Shafir said. He and Mullainathan were co-authors on a 2012 Science paper that reported a higher likelihood of poor people to engage in behaviors that reinforce the conditions of poverty, such as excessive borrowing.

“They can make the same mistakes, but the outcomes of errors are more dear,” Shafir said. “So, if you live in poverty, you’re more error prone and errors cost you more dearly — it’s hard to find a way out.”

The first set of experiments took place in a New Jersey mall between 2010 and 2011 with roughly 400 subjects chosen at random. Their median annual income was around $70,000 and the lowest income was around $20,000. The researchers created scenarios wherein subjects had to ponder how they would solve financial problems, for example, whether they would handle a sudden car repair by paying in full, borrowing money or putting the repairs off.

Participants were assigned either an “easy” or “hard” scenario in which the cost was low or high — such as $150 or $1,500 for the car repair. While participants pondered these scenarios, they performed common fluid-intelligence and cognition tests.

Subjects were divided into a “poor” group and a “rich” group based on their income. The study showed that when the scenarios were easy — the financial problems not too severe — the poor and rich performed equally well on the cognitive tests. But when they thought about the hard scenarios, people at the lower end of the income scale performed significantly worse on both cognitive tests, while the rich participants were unfazed.

To better gauge the influence of poverty in natural contexts, between 2010 and 2011 the researchers also tested 464 sugarcane farmers in India who rely on the annual harvest for at least 60 percent of their income. Because sugarcane harvests occur once a year, these are farmers who find themselves rich after harvest and poor before it. Each farmer was given the same tests before and after the harvest, and performed better on both tests post-harvest compared to pre-harvest.

The cognitive effect of poverty the researchers found relates to the more general influence of “scarcity” on cognition, which is the larger focus of Shafir’s research group. Scarcity in this case relates to any deficit — be it in money, time, social ties or even calories — that people experience in trying to meet their needs. Scarcity consumes “mental bandwidth” that would otherwise go to other concerns in life, Zhao said.

“These findings fit in with our story of how scarcity captures attention. It consumes your mental bandwidth,” Zhao said. “Just asking a poor person to think about hypothetical financial problems reduces mental bandwidth. This is an acute, immediate impact, and has implications for scarcity of resources of any kind.”

“We documented similar effects among people who are not otherwise poor, but on whom we imposed scarce resources,” Shafir added. “It’s not about being a poor person — it’s about living in poverty.”

Many types of scarcity are temporary and often discretionary, said Shafir, who is co-author with Mullainathan of the book, “Scarcity: Why Having Too Little Means So Much,” to be published in September. For instance, a person pressed for time can reschedule appointments, cancel something or even decide to take on less.

“When you’re poor you can’t say, ‘I’ve had enough, I’m not going to be poor anymore.’ Or, ‘Forget it, I just won’t give my kids dinner, or pay rent this month.’ Poverty imposes a much stronger load that’s not optional and in very many cases is long lasting,” Shafir said. “It’s not a choice you’re making — you’re just reduced to few options. This is not something you see with many other types of scarcity.”

The researchers suggest that services for the poor should accommodate the dominance that poverty has on a person’s time and thinking. Such steps would include simpler aid forms and more guidance in receiving assistance, or training and educational programs structured to be more forgiving of unexpected absences, so that a person who has stumbled can more easily try again.

“You want to design a context that is more scarcity proof,” said Shafir, noting that better-off people have access to regular support in their daily lives, be it a computer reminder, a personal assistant, a housecleaner or a babysitter.

“There’s very little you can do with time to get more money, but a lot you can do with money to get more time,” Shafir said. “The poor, who our research suggests are bound to make more mistakes and pay more dearly for errors, inhabit contexts often not designed to help.”

Ref. Anandi Madi et al., Poverty Impedes Cognitive Function. Science 2013. Pay per view → LINK [doi:10.1126/science.1238041]

I must say that I find extremely sad that a study so important for people of scarce resources is pay per view.

 

Claim that Danubian Neolithic people had classes

Or so is what new research has led many to think.

R. Alexander Bentley et al., Community differentiation and kinship among Europe’s first farmers. PNAS 2012. Pay per view (for six months or depending on your world region).

Abstract

Community differentiation is a fundamental topic of the social sciences, and its prehistoric origins in Europe are typically assumed to lie among the complex, densely populated societies that developed millennia after their Neolithic predecessors. Here we present the earliest, statistically significant evidence for such differentiation among the first farmers of Neolithic Europe. By using strontium isotopic data from more than 300 early Neolithic human skeletons, we find significantly less variance in geographic signatures among males than we find among females, and less variance among burials with ground stone adzes than burials without such adzes. From this, in context with other available evidence, we infer differential land use in early Neolithic central Europe within a patrilocal kinship system.

Many details on the burials are freely available in the supplemental material. The necropolises (many individuals each) are from a diversity of sites between Slovakia and Alsace: Aiterhofen, Ensisheim, Kleinhadersdorf, Nitra, Souffelweyersheim, Schwetzingen and Vedrovice.

The key relevant finding seems to be that most males buried with adze have lower Sr87/Sr86 ratio in their tooth enamel than those buried without grave goods, suggesting that they were more likely be original from the more fertile loess lands than the others, the preferred location of Linear Pottery Culture sites (also Danubian Neolithic or LBK by its German acronym). 

Women overall also had lower Sr87/Sr86 ratio, suggesting that most had come from other less fertile districts. This last also implies patrilocality, surely dismantling the idea of Gimbutas of a matrilocal “Old Europe”, which was already very much discredited (notice that this is not important in regard to her most important theory: the Kurgan model of Indoeuropean expansion, which is only very tangentially related to this matter). 

However my first impression is that drawing such radical conclusions from evidence which is only somewhat significant (I see many non-adze men who have below average strontium ratios and also a good number of adze men with high Sr ratios) and not at all absolute, seems a bit risky on first sight.

Whatever the case that is what they claim: that Danubians had classes or castes or some sort of social hierarchy and differentiation since the very beginnings. Sadly they have not researched what could have been a complementary source of information: DNA. 

Sources: Eureka Alert, Science, BBC, Pileta[es].

Western Danubian overlapped with pottery styles that can be aboriginal or Cardium-derived (source: Westward Ho!)

 

Genetic predisposition and physical punishment converge into forging violent behavior in boys

Who could blame them? If your genes include a tendency towards violence and your parents teach you violence by means of violent punishments such as spanking, you will probably behave violently. That’s the conclusion of a new study on the matter:

Brian B. Botwell et al., Physical punishment and childhood aggression: the role of gender and gene–environment interplay. Aggressive Behavior 2012. Pay per view. 

However the results appear to show no or very little effect in girls instead:

“It did not affect females,” he said. “Males who were spanked and had the highest genetic risks displayed the most aggressive behavior compared to other males.”

Source and more details at Science Daily.

 

The rich are rich because they are greedy and cheat

There’s a new study out there set to open some minds to reality:

Raul K. Piff et al., Higher social class predicts increased unethical behavior. PNAS 2012. Pay per view (free in six months or already depending on global region).

Abstract

Seven studies using experimental and naturalistic methods reveal that upper-class individuals behave more unethically than lower-class individuals. In studies 1 and 2, upper-class individuals were more likely to break the law while driving, relative to lower-class individuals. In follow-up laboratory studies, upper-class individuals were more likely to exhibit unethical decision-making tendencies (study 3), take valued goods from others (study 4), lie in a negotiation (study 5), cheat to increase their chances of winning a prize (study 6), and endorse unethical behavior at work (study 7) than were lower-class individuals. Mediator and moderator data demonstrated that upper-class individuals’ unethical tendencies are accounted for, in part, by their more favorable attitudes toward greed.

They even justify their unethical behavior because for them greed is somehow ethical, something good (as Reagan would memorably state in his reign), justifying almost everything (while for the rest of us it is obviously not). 

I wonder if there is a greedy gene and if we could inactivate it with genetic engineering. Of course I also wonder if such thing could be ethical… but sounds better than guillotine, right?

In the media: The Independent, Kaos[es].

Other great discoveries of modern psychological science: conservatives are quite scared, and progressive and open minded people are generally smarter.

 

Some quick prehistory news

P. boisei reconstruction

Quickly some archaeological or otherwise prehistorical news, mostly (but not only) from Stone Pages‘ newsletter ArchaeoNews.

Paranthropus sp. were patrilocal: enamel analysis finds that females were much more mobile than males in this hominin genus > SD.

Autism was maybe selected for in scattered hunter-gatherer populations > SD.

The effective population size of the first Native Americans was maybe of just 70 > Daily Mail [update: it seems to be on <a href=http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030193 >a 2005 paper</a>, not really new].

Geometric rock art and “rock gongs” in Northern Sudan (Wadi Abu Dom) may be 5000 years old > Live Science, UPI.  

Newly found Australian skull might date to as much as  25,000 years ago > ABC.

Barrows (tumuli) excavated in Dorset (England) before the sea destroys them > BBC.

Large dolmen tomb discovered at Srikakulam (Andrah Pradesh, India) > Times of India.

 

Bonobo and chimpanzee brains differ in wiring

Bonobo relaxing

They have similar sized brains, they look alike enough for bonobos to have been called once “pygmy chimpanzees”, and in fact they belong to the same genus (Pan) having diverged some 1.3 to 2 million years ago (or 1.7-2.6 Ma following the logical thread of a newer paper). Their differences are therefore perfectly comparable to those among Homo species (all but H. sapiens extinct by now).

For this reason and because they are very close relatives of us (we diverged some 8-10 Ma ago), the two Pan sp. species are a major reference for anthropology, not the least because they display so different psychologies and sociologies in spite of being so closely related: while chimpanzees are male-centric, hierarchical, violent and retain female sexual (and not just reproductive) cycles, bonobos are female-centric, cooperative, peaceful and joyful and have sex all the time. Bonobos are also empathic like us, while the empathy of chimpanzees is, if it exists at all, quite shallow.

Now a new paper, using non-invasive brain scan techniques, has managed to discern the differences in what we can well call central wiring in the brains of chimpanzees and bonobos:

James K. Rilling et al., Differences between chimpanzees and bonobos in neural systems supporting social cognition. Social Cognitive and Affective Neuroscience, 2011. Pay per view.

The paper is discussed at Science Daily. 

A look at chimpanzee (L) and bonobo (R) central network (from the press release)

Interestingly (from the SD article):

The results showed that bonobos have more developed circuitry for key nodes within the limbic system, the so-called emotional part of the brain, including the amygdala, the hypothalamus and the anterior insula. The anterior insula and the amygdala are both implicated in human empathy.

“We also found that the pathway connecting the amygdala and the prefrontal cortex is larger in bonobos than chimpanzees,” Rilling says. “When our amygdala senses that our actions are causing someone else distress, we may use that pathway to adjust our behavior in a prosocial direction.”

Chimpanzees have better developed visual system pathways, according to the analysis. Previous research has suggested that those pathways are important for tool use, a skill which chimpanzees appear better at than bonobos.

 

Challenging ‘behavioral modernity’

This issue of behavioral modernity is something I have never really accepted from mainstream Prehistory and Anthropology. In this conceptual paradigm or intellectual fetish (whatever you prefer to call it), humankind almost suddenly emerged from the amorphous shadows of what we could call (by contrast) behavioral primitivism and began being us, maybe when they decided to create some perdurable art like that we can find in the caves of Southwestern Europe and the related technologies defined as mode four (or blade-based stone industries or Upper Paleolithic in the narrowest possible sense). 

The reference is silly and eurocentric but very real in these academic fields. As of late, the finding of other, more ancient and not really European expressions of prehistoric artwork, notably in Palestine, North Africa and South Africa (in this chronological order per the available data) allowed the concept to escape its original sin of Eurocentrism somewhat but, regardless, is the concept real?

A new study by John J. Shea, published in Current Anthropology (pay per view, discussed at Science Daily), challenges this, already quite shattered perception of some almost miraculous transition towards behavioral modernity on scientific grounds: Shea analyzes the rather well documented early Humankind in East Africa between 250,000  and 6000 years ago, and finds no linear pattern of evolution but rather an outstanding array of nonlinear diversity. 

From the news article:

A systematic comparison of variability in stone tool making strategies over the last quarter-million years shows no single behavioral revolution in our species’ evolutionary history. Instead, the evidence shows wide variability in Homo sapiens toolmaking strategies from the earliest times onwards. Particular changes in stone tool technology can be explained in terms of the varying costs and benefits of different toolmaking strategies, such as greater needs for cutting edge or more efficiently-transportable and functionally-versatile tools. One does not need to invoke a “human revolution” to account for these changes, they are explicable in terms of well-understood principles of behavioral ecology.