Category Archives: evolution

The how of social capital

Flickr/drjausSocial capital is a powerful resource for individuals and communities.  For individuals embedded in dense social networks, these networks and the attendant norms of trust and reciprocity strongly shape individuals’ ability to land jobs, earn higher salaries, and be happier and healthier.  But, even for those not in the networks, having neighbors who know and trust one another affords benefits in some domains:  better performing local government, safer streets, faster economic growth and better performing schools, among other public goods.

For sure social capital can be used toward negative ends: Al Qaeda, the Crips and the Bloods, the Michigan Militia are all examples where group members can accomplish things that they could not accomplish individually (because of  group social capital).  That said, the literature supports that the vast majority of what social capital is used for is to produce positive ends, not negative ones.

But why?  What makes social capital so powerful?

Robert Putnam and I had always focused on information-flows as the key mechanism.  So these social networks:

  • enable individuals to access valuable information: how to get something done, hear of  job leads, learn how better to promote one’s health, find out what is happening in a community, etc.; or
  • help individuals find partners for joint economic transactions (e.g., to know with whom to partner  in business, to close a sale to a friend or a friend of a friend, to locate a neighbor with whom one can exchange tools or expertise); or
  • spread reputations of members (or neighbors or local merchants) which causes all people in these networks to behave in a more trustworthy manner and facilitates altruism.  There is always a short-term gain to be had from cheating someone, but if the social networks quickly spread the information that one cannot be trusted, this short-term gain is swamped by the lost future opportunity to do business with others; thus it becomes more rational to be honest and trustworthy in communities (physical or otherwise) with strong social networks. Individuals are also likely to be kinder and more altruistic toward others because they know that “what goes around comes around” in densely inter-connected networks and communities; and
  • facilitate collective action: it is easier to mobilize others around some shared goal like politics or zoning or improving trash pick-up if others in the  community already know and  trust you, rather than your having to build those social relationships from scratch.

But Connected (by Nick Christakis and James Fowler) raises a different frame for thinking about this issue: network effects or contagion.  Are there properties of the networks themselves that help spread practices, independent of the flow of information?  This is difficult to answer fully since much of their evidence comes from the Framingham Heart Study where  they know who people’s friends are but not what they are doing with each other or what they are saying to each other.

That said, some of their results can be explained by information flows (e.g., political influence, or getting flu shots), but some seem likely to be working through other channels and not through information-flows (e.g., happiness or loneliness cascades).

In these “network effects” or contagion, Fowler & Christakis typically find that the strongest “network” effects are directly with one’s friends (one degree of separation), but these effects also ripple out two more levels to  friends of one’s friends (two degrees) and friends of the friends of one’s friends (three degrees).  As one would expect, much like a stone dropped in a pond, the ripples get smaller as one moves out.  In fact they refer to the “Three Degrees of Influence” Rule that effects are typically only seen up to three degrees out and not further: in the spread of happiness, political views, weight gain, obesity, and smoking.  For example, in happiness, if one is happy, one degree out (controlling for other factors), one’s friends are 15% happier, at 2 degrees of separation they are 10% happier, and they are 6% happier at 3 degrees of separation.  For obesity, the average obese American is more likely to have obese friends, one, two and three degrees of separation out, but not further.  Quitting smoking has diminishing effects out to three degrees.  For political influence, they note a “get-out-the-vote” experiment that shows that knocking on a stranger’s door and urging the resident to support a recycling initiative had a 10% impact on his/her likelihood to vote for the initiative; what was noteworthy to Christakis and Fowler is that the door-knocking made the spouse (who was not at the door) 6% more likely to support the recycling initiative based on communication with his/her spouse.  They conjecture that if this 60% social pass-through rate of political appeals (6% for spouse vs. 10% for person answering door) applied to one’s friends and if everyone had 2 friends, then one person urging friends to vote a certain way would have a 10% impact on one’s friends, a 6% impact on one’s friends’ friends (2 degrees) and a 3.6% impact 3 degrees out.  Multiplying these political effects all the way through, one vote could create a 30x multiplier. [The example is eye-opening and suggests that voting and political persuasion may be less irrational than thought, but also is based on a huge number of assumptions and assumes no cross-competing messages from friends.]

In an experiment on altrusim (explained in this post) Christakis & Fowler found that $1.00 of altruism, ultimately produced $1.05 of multiplier effect ($.20 one ripple out with 3 others and $.05 of altruism two ripples out with 9 others).

Christakis and Fowler, in their book, talk about contagion effects in voting, suicide, loneliness, depression, happiness, violence, STDs, number of sexual partners, binge drinking, back pain, and getting flu shots, among others.  [One summary of many of their findings, which they note, is “You make me sick!”]

Why do these effects only reach out 3 degrees of influence?  Christakis & Fowler suggest 4 potential explanations.

1) intrinsic decay: C&F liken this to a game of telephone where as the information gets repeated, the content gets lost, or the passion and knowledge of the initiator gets dissipated.

2) Instability of ties: because of what is known as “triadic closure“, if A is friends with B and B is friends with C, it is likely that A will become friends with C.  Because of this, closer-in ties between people have more routes connecting them, and further out ties are more dependent on only one pathway connecting them.  For example, assume Abby and Fran were friends 3 degrees removed via Bert and via Charles. If any of these intervening friendships end (say Bert is no longer friends with Charles), Abby loses her tie to Fran.  Thus, these outer ties are much less stable and averaged across all the “3 degrees of influence” friendships, many more may have zero effect because the path of influence dies out as friends change.

3) cross-information:  as one gets further out away from you, say the friends of the friends of your friends, all of these folks are getting lots of cross-stimuli from lots of other sources (many of which may come from different clusters with different habits or values) and these cross-stimuli start to cancel each other out.

4) evolutionary biology: C&F note that humans evolved in small groups that had a maximum of three degrees of separation so it may be that we became more attuned to being influenced by folks who were in a position to alter our gene pool.

So what are the network influences independent of communication.  There seem like 6 possible channels, and often it is hard to separate one from the other, although some may make more sense for the spread of behaviors and others may make more sense for spread of attitudes or emotions:

1) homophily: “Homophily” is the practice of befriending others like you — “birds of a feather flock together.” Being friends with people who are different than you can be stressful.  This is why in mates and in friends we are likely to choose others with whom we have a lot in common — think of arguments you’ve had with friends about where to go for dinner or what is right or wrong with the world when those friends have very different tastes or politics.  For this reason, one reason for increased clustering over time of obese people or smokers or binge drinkers is that it is stressful to be in groups where one is the minority and either constantly noodging others to change their behavior or else your finding yourself frequently doing what your friends want to and what you do not (e.g., eat fast food, smoke, or listen to heavy metal rock music).  As a consequence, people may vote with their feet and form new ties or strengthen ties with others with whom they have more in common.

2) norms/reference groups/culture/peer pressure:   we often measure the reasonableness of our behavior against our friends.  For example, if our teen friends have all had 6 sexual partners in the last year, then repartnering seems far more normal than if one is friends with a group that is heavily monogamous.  Ditto with obesity or smoking or other possible traits or behaviors.

3) subconscious/imitation:  as suggested with “emotion” below, sometimes we mirror others’ behavior or emotions without even thinking about it.  C&F say it makes sense to think of people as subsconsciously reacting to those around them without being aware of any larger pattern.  They talk about processes by which a “wave” at a sporting event takes place, or fish swim in unison, or geese fly in a V-formation, or crickets become synchronized — all of these happen by individuals mirroring those around them.  And in the process, emergent properties of the group arise (much like a cake takes on the taste unlike any of its individual ingredients).

4) emotions: C&F note that emotions actually affect our physical being — our voices, our faces, our posture.  In experiments, people actually “catch emotions”: others become happier by spending time around happy people or sadder by hanging out with depressed individuals.  In experiments, smiling waiters get bigger tips.  It seems quite plausible that cascades like loneliness, happiness, depression, etc. could spread simply from emotional states, independent of any information flowing through these friendships.

5) social invitations for shared action: friends often invite friends to do things — that’s part of friendship. For behaviors, one of the ways they can spread through networks is that, for example, thin friends could invite friends to exercise more, or obese friends could encourage friends to get ice cream together, or smokers could encourage others to leave the dance for a cig.

Connected notes that it is often hard, for example, to tell imitation and norms apart, “When a man gives up his motorcycle after getting hitched, is he copying his wife’s behavior (she doesn’t have a motorcycle) or adopting a new norm (the infernal things are unsafe?)”

Connected also notes how behaviors or attitudes can spread several social links out, even without the intervening link changing.  They suggest that Amy could have a friend Maria who has a friend Heather.  (Amy and Heather don’t know one another.)  Heather gains weight.  Maria, who really likes Heather, becomes less judgmental of her weight and gradually less judgmental of  obesity in general.  Maria doesn’t change her behavior but when Amy stops exercising with Maria, Maria is less likely to pressure her to resume.  Thus Heather’s obesity changes Amy via Maria (by Maria no longer urging her to keep exercising), but Maria doesn’t change her behavior and Amy and Heather don’t know one another.

It’s interesting stuff to ponder and makes one think more expansively about the role and mechanisms of social capital.  It also evokes a conversation with a Saguaro Seminar participant back in 1998 concerning whether black kids and white kids doing sidewalk painting together on the steps of an art museum could promote inter-racial trust, even if the black kids and white kids didn’t know each other, didn’t talk to one another and never met again.  [My hunch is yes, depending on the strength of their pre-existing beliefs about inter-racial trust, but that talking could make the exchange far more powerful.] Another Saguaro participant wondered whether singing together in a chorus helps build social capital, even if one never has a conversation directly with another member of the chorus.  (In the latter example, in addition to being highly unlikely, you are at least getting some non-verbal information over time from the other choral members about their trustworthiness: do they come regularly and on time, do they respectfully listen to and follow the choralmeister?)

I welcome your thoughts.

For more on the network effects, read pp. 24-30, 25-43 and 112-115 in Connected.

Socializing expands brain size?

Flickr photo by taod

This is by no means an overnight phenomenon.

Scholars at Oxford have refuted the notion that all mammals over time developed larger brains.  Instead Dr. Susanne Shultz and Prof. Robin Dunbar found over a span of 60 million years that more social creatures, among them humans, had the most rapidly expanding brain sizes to cope with the complexity of collaboration, social norms and coordination.

“The research team analysed available data on the brain size and body size of more than 500 species of living and fossilised mammals. It found that the brains of monkeys grew the most over time, followed by horses, dolphins, camels and dogs. The study shows that groups of mammals with relatively bigger brains tend to live in stable social groups. The brains of more solitary mammals, such as cats, deer and rhino, grew much more slowly during the same period.”

They noted that the fact that cats’ brains did not expand while dogs’ and horses’ brains did, can be accounted for by the far more solitary lives that cats lead in relation to dogs and horses, which interact far more with humans.

Obviously, since these evolutionary anthropologists couldn’t go back in time to distinguish social cavemen from more solitary cavemen, it is impossible to tell whether the expansion of brain size was related to the average levels of socialization of a species or whether this same pattern would have held true at the individual level: with offspring of more social parents having larger brains than offspring of less social humans.

Nonetheless, food for thought…  The implication: get out and socialize and help our species to continue to grow our average brain size, although the results may not be noticeable within your lifetime.

See “Socialising led to bigger brains in some mammals

The study is called “Encephalization is not a universal macroevolutionary phenomenon in mammals but is associated with sociality” (PNAS Journal, November 30, 2010, by Susanne Shultz and Robin Dunbar).  Abstract here.

Shultz and Dunbar’s center, Oxford University’s Institute of Cognitive and Evolutionary Anthropology, is here.

Our genes influence our social networks

Chromosomes magnified - photo by BlueSunFlower

Chromosomes magnified - photo by BlueSunFlower

If you don’t have enough friends or aren’t the social butterfly of your class, now you can blame your genes.

Nick Christakis (Harvard Medical School) and James Fowler (UCSD political scientist) are back with more controversial findings suggesting some genetic determination in our social networks (both in forming friendships and determining where we are in social networks).  Christakis: “the beautiful and complicated pattern of human connection depends on our genes to a significant measure.”  Previous work by Christakis looked at how our social networks and who is in them shape our likelihood of obesity, happiness, and smoking, among other outcomes.

They researched 1,100 same-sex twins in the National Longitudinal Study of Adolescent Health (colloquially called “Add Health”). Add Health examined high school students in 1994-1995 and asked questions regarding economics, physical health and social involvement. Christakis and Fowler compared the social networks and patterns of identical same-sex twins against fraternal ones to separate nature (genes) from nurture (upbringing).

Their findings go far beyond what people might think about the genetic influence on personality traits (being outgoing, shy, etc.). For example, how often the subject was named as a friend and the likelihood that the subject’s friends knew one another were strongly genetically influenced, but interestingly not the number of friends that the subject listed. This suggests a genetic determinant of being popular (beyond a simple disposition toward being outgoing); further buttressing this interpretation, whether the subject was more the center of attention (central to these networks) or more of a social outcast (peripheral to these networks) was also heritable.

Christakis admits that some of the findings are puzzling, like the fact that the likelihood that my friends Bill and John know each other is attributable to my genes; what this likely means is that some people are genetically disposed to introduce their friends to each other more or to host or arrange social events where these friends would have chances to meet each other.

‘Given that social networks play important roles in determining a wide variety of things ranging from employment and wages to the spread of disease, it is important to understand why networks exhibit the patterns that they do,’  Matthew Jackson, a Stanford University economist, wrote in a commentary accompanying the study called “Do We Inherit Our Positions in Life?”.

James Fowler… said its implications go beyond the theoretical. For some time, scientists have suspected a genetic role in certain conditions, such as obesity. Now, Mr. Fowler wants to investigate whether the dynamics of social networks might affect public-health outcomes, for instance, by exposing people to certain behaviors, such as smoking.”

“Our work shows how humans, like ants, may assemble themselves into a ‘super-organism’ with rules governing the assembly, rules that we carry with us deep in our genes,” says Nicholas Christakis.  Christakis et al. also believe that there may be an evolutionary explanation for their findings since one’s position in social networks had costs or benefits to the survival of one’s genes. Being central to a group likely contributed to survival during periods of food scarcity since one could learn where food supplies were, while being peripheral to groups helped genes survive in periods where deadly germs were being transmitted by social contact. Christakis: “It may be that natural selection is acting on not just things like whether or not we can resist the common cold, but also who it is that we are going to come into contact with.”  The paper notes: “There may be many reasons for genetic variation in the ability to attract or the desire to introduce friends.  More friends may mean greater social support in some settings or greater conflict in others.  Having denser social connections may improve groupsolidarity, but it might also insulate a group from beneficial influence or information from individuals outside the group.”  The authors note that more work is required to understand what specific genes are at work and what possible mediating mechanisms might be.

The authors acknowledge some controversy in studies comparing identical twin studies to fraternal twins, with critics noting that identical twins may have a stronger affiliation with  each other that causes them to be more influenced by each other than fraternal twins.  The authors note that twin studies have been validated by comparing identical twins raised apart versus together (suggesting that it is not the shared environment).  The authors further note that personality and cognitive differences between identical and fraternal twins persist even among twins mistakenly believed to be identical by their parents (indicating that parental patterns in raising these ‘identical twins’ can’t explain the outcome).  Finally, they note that that once twins reach adulthood, identical twins living apart tend to become more similar with age, which doesn’t fit with a notion of the importance of their shared environment.

The study appeared online in James Fowler, Christopher Dawes and Nicholas Christakis,  “Model of Genetic Variation in Human Social Networks” in Proceedings of the National Academy of Sciences journal (January 26, 2009).

“More specifically, the results show that genetic factors account for 46% [95% confidence interval 23%, 69%] of the variation in in-degree (how many times a person is named as a friend), but heritability of out-degree (how many friends a person names) is not significant (22%, CI 0%, 47%). In addition, node transitivity [the likelihood that two of a person’s contacts are connected to each other] is significantly heritable, with 47% (CI 13%, 65%) of the variation explained by differences in genes. We also find that genetic variation contributes to variation in other network characteristics; for example, bertween-ness centrality [the fraction of paths through the networks that pass through a given node] is significantly heritable (29%, CI 5%, 39%).”

See also “Genes and the Friends You Make” (Wall Street Journal, 1/27/09 by Philip Shishkin)

See other articles by Christakis et. al on social networks.

Interesting series of articles on trust

(photo by A Stump)

(photo by A Stump)

In the current issue of “Greater Good” magazine, Pamela Paxton (sociology, Ohio State) and Jeremy Adam Smith have a cover story “America’s Trust Fall” about the declines over the last generation in social trust and trust in American institutions.  It’s a good overview of this topic.

But the issue also addresses other related issues of trust.

1.In Faces We Trust describes research of Alexander Todorov (psychology, Princeton) and colleagues showing how important gut instincts our to our trust judgments and to political decisions.

In one 2006 experiment, they gave participants small amounts of time—100 milliseconds, 500 milliseconds, and 1 second—to judge if a face was trustworthy. The researchers discovered that decisions made after 100 milliseconds were highly consistent with decisions made with longer time constraints, suggesting that …beyond those first 100 milliseconds, additional time for reflection doesn’t appear to change first impressions….

Follow-up research in 2007 tested whether these gut reactions had implications for politics.  They showed experimental participants pictures of the winner and runner-up of various Senate and gubernatorial races that participants were unfamiliar with and asked, “Who is more competent?”

After only 100 milliseconds of exposure to the faces, participants chose the winning candidate for about 72 percent of the Senate races and 69 percent of the gubernatorial races. In other words, gut instincts were highly consistent with actual votes cast after many months of supposedly rational deliberation.

Similarly, a 2006 experiment by economists Daniel Benjamin and Jesse Shapiro revealed that people were remarkably able to determine the election outcome from watching silent 10-second clips of political debates.   Ironically, experimental subjects were less likely to be able to predict the election outcome if they listened to the sound since it seemed to interfere with their gut instincts.

Researchers posit that these gut reactions and “thin slices” of information have deep evolutionary roots. “Neuroimaging studies reveal that trust evaluations involve the amygdala, a brain region responsible for tracking potential harm—something that probably came in handy on the prehistoric African savanna, where judging trustworthiness in a split second could well mean the difference between life and death.”

While these snap judgments appear to anchor our initial decision, experiments have shown that we engage in a series of internal subconscious arguments between rational thought and these gut feelings and that subsequent data can overcome our initial biases.

2. Brain Trust discusses what researchers know about the trust process from monitoring our brains.  They discuss experiments that show that we often do not behave in self-maximizing ways out of a sense of trust or fairness.

“Familiarity breeds trust—players tend to trust each other more with each new game. So does introducing punishments for untrustworthy behavior, or even just reminding players of their obligations to each other.”

“These studies have demonstrated the strength of human trust, and that humans are truly worthy of this trust from one another. They have also improved our understanding of the social factors that determine trust. But two important questions remain: Is trust truly a biologically based part of human nature, and if so, what is it in the brain that makes humans trust each other?”

The article discusses evidence that oxyocin “greases the wheels of trust” but only when humans are facing other humans, not when they are playing against computers.

3. In Can I Trust You? psychologist Paul Ekman (a pioneer in determining who is lying from facial cues) converses with his daughter Eve. He discusses how an expert on lying, deception, and truthfulness tries to foster trust and trustworthiness in his daughter, why it is important, and what it takes.

He notes that he tried to avoid putting her in a position where she would lie, but instead asked leading questions encouraging her to disclose (e.g., “”Is there something on your mind? Is there something you want to talk about?” or “What happened the other night? I heard you come in late.”)

He notes the difficult role of a parent:

[Y]ou have to keep moving backwards. When parents start out, they are completely responsible for their child, who is totally helpless. As that child grows, you have to roll back, you have to grant control; otherwise, your child can’t grow. You have to be able to live with the fact that as you grant the child more autonomy, they will get into all sorts of trouble. But you ultimately have to leave it up to them.

He notes the importance of not simply trying to rely on the authority inherent in the parental role, but explaining the basis for actions and appealing to higher moral principles.  And he urges parents to avoid “destructive compassion”: when you are so worried about your child that you over–control them and damage them.  He tried to set an example by never lying in his own life, and tried to make clear that disclosure about trouble that the kids got into was part of their responsibility.  Making obligations clear was important.  His wisdom is summarized in Why Kids Lie: How Parents Can Encourage Truthfulness.

4. Psychologist Joshua Coleman describes how to reinstill trust in romantic relationships of couples who have had a falling out in Surviving Betrayal.

Would I lie to you? (Engineering trust with your face)

Spurred by the ever-more-bizarre case of impostor Clark Rockefeller, the Boston Globe featured a very interesting story on Aug. 17 on how con-men engineer trust.

The article talks about how mimicking the speaker’s movements creates trust (even when the speaker is unaware of this mimicking), how minutely small bonds between individuals (like claiming that you used the same amount of paint in a recent paint job) makes one’s recommendations in a paint store be taken more seriously, and how MIT-researchers have been able to use sociometers (measuring the intonation of one’s voice, distance away, which way one was facing, etc.) to be able to predict which business pitches people would find persuasive or not.

Some of the most interesting research is on facial features (which brings to mind a very interesting story a while back by Malcolm Gladwell called “The Naked Face“).

Author Bennett notes that things as small as the slope of the eyebrow or the thickness of the chin send signals about whether they are to be trusted. “According to recent work by Nikolaas Oosterhof and Alexander Todorov of Princeton’s psychology department, we form our first opinions of someone’s trustworthiness through a quick physiognomic snapshot. By studying people’s reactions to a range of artificially-generated faces, Oosterhof and Todorov were able to identify a set of features that seemed to engender trust. Working from those findings, they were able to create a continuum: faces with high inner eyebrows and pronounced cheekbones struck people as trustworthy, faces with low inner eyebrows and shallow cheekbones untrustworthy.

“In a paper published in June, they suggested that our unconscious bias is a byproduct of more adaptive instincts: the features that make a face strike us as trustworthy, if exaggerated, make a face look happy – with arching inner eyebrows and upturned mouths – and an exaggerated untrustworthy face looks angry – with a furrowed brow and frown. In this argument, people with trustworthy faces simply have, by the luck of the genetic draw, faces that look a little more cheerful to us.

“Just as in other cognitive shorthands, we make these judgments quickly and unconsciously – and as a result, Oosterhof and Todorov point out, we can severely and immediately misjudge people. In reality, of course, cheekbone shape and eyebrow arc have no relationship with honesty.”

It appears that for evolutionary purposes, it was important to be able to make relatively rapid judgments of whom could be trusted. It seems weird that over millennia, genes wouldn’t have had a hereditary advantage that came up with better heuristics for assessing trust than this one commonly used (if it had no relationship with honesty). Then again, it may be that facial expressions in concert with other signals from the speaker (tone, style, affect, excitement, sweat, etc.) were actually relatively good proxies for truth-telling. For sure those who weren’t very good at judging who was going to stab them in the back, generally didn’t live long enough to be able to pass on their genes.

Read the whole interesting article “Confidence Game” (Boston Globe, 8/17/08 by Drake Bennett)