Category Archives: brain

How loneliness kills



Judith Shulevitz, in the May 13, 2013 New Republic has an interesting read “The Lethality of Loneliness.”


“Psychobiologists can now show that loneliness sends misleading hormonal signals, rejiggers the molecules on genes that govern behavior, and wrenches a slew of other systems out of whack. They have proved that long-lasting loneliness not only makes you sick; it can kill you. Emotional isolation is ranked as high a risk factor for mortality as smoking. A partial list of the physical diseases thought to be caused or exacerbated by loneliness would include Alzheimer’s, obesity, diabetes, high blood pressure, heart disease, neurodegenerative diseases, and even cancer—tumors can metastasize faster in lonely people….

“To the degree that loneliness has been treated as a matter of public concern in the past, it has generally been seen as a social problem—the product of an excessively conformist culture or of a breakdown in social norms. Nowadays, though, loneliness is a public health crisis. The standard U.S. questionnaire, the UCLA Loneliness Scale, asks 20 questions that run variations on the theme of closeness—“How often do you feel close to people?” and so on. As many as 30 percent of Americans don’t feel close to people at a given time….

“What He [God] wanted is for us not to be alone. Or rather, natural selection favored people who needed people. Humans are vastly more social than most other mammals, even most primates, and to develop what neuroscientists call our social brain, we had to be good at cooperating. To raise our children, with their slow-maturing cerebral cortexes, we needed help from the tribe. To stoke the fires that cooked the meat that gave us the protein that sustained our calorically greedy gray matter, we had to organize night watches. But compared with our predators, we were small and weak. They came after us with swift strides. We ran in a comparative waddle.

“So what would happen if one of us wandered off from her little band, or got kicked out of it because she’d slacked off or been caught stealing? She’d find herself alone on the savanna, a fine treat for a bunch of lions. She’d be exposed to attacks from marauders. If her nervous system went into overdrive at perceiving her isolation, well, that would have just sent her scurrying home. [John] Cacioppo thinks we’re hardwired to find life unpleasant outside the safety of trusted friends and family, just as we’re pre-programmed to find certain foods disgusting. “Why do you think you are ten thousand times more sensitive to foods that are bitter than to foods that are sweet?” Cacioppo asked me. “Because bitter’s dangerous!”

The article, well worth a read, discusses issues like that only about half of loneliness is hereditary, what areas of the brain light up when we are socially snubbed (the same portion that registers physical pain, i.e., the dorsal anterior cingulate cortex), what has been learned about the impact of the absence of loving parents on loneliness from the isolating experience of Russian orphans; and how Nobelist James Heckman is finding that many low SES children bear loneliness scars from poor parenting growing up (that is akin to the impact found by Steve Suomi and Harry Harlow on isolated rhesus macaques).

See other posts about the negative health effects and contagion of  loneliness and social isolation here.

The science of friendship

Flickr/JimBoudThere is an interesting article by Robin Dunbar in The New Scientist: Dunbar’s Number was named after Robin, from his theorizing that humans only had the brain capacity to manage roughly 150 relationships, although depending on gender, social skills and personality, this number could vary from 100-250.  Dunbar observes that communication often breaks down when one exceeds 150 individuals (as evidenced in the Crimean War by the Charge of the Light Brigade) and the modern military and businesses only exceed these limits through strict hierarchies.

Dunbar theorizes that language, laughter and communal music-making evolved as a way to stay connected to a larger group of individuals than possible through physical acts like grooming. Dunbar: “[N]ot only can we speak to many people at the same time, we can also exchange information about the state of our networks in a way that other primates cannot. Gossip, I have argued, is a very human form of grooming.”  Christakis and Fowler (in the excellent book Connected) note that “…language is a less yucky and more efficient way to get to know our peers since we can talk to several friends at once but only groom them one at a time.  In fact, in a conversation with a small group, we can assess the behavior, health, aggressiveness, and altruism of several individuals simultaneously.  Plus, we can talk to someone else while engaged in another activity, like foraging for food in a refrigerator.”  Christakis and Fowler note how radical the idea is that language evolved not primarily as a way to exchange information but to maintain group cohesion.   “Dunbar estimates that language would have to be 2.8 times more efficient than grooming in order to sustain the [average] group size seen in humans” (one speaker per 2.8 listeners).

While language may have originally evolved, as per Dunbar, to maintain a slightly larger group size, once developed it was in principle possible to use language to maintain social relations on a tribal or national level.

A few other excerpts from Dunbar’s article:

Group living needn’t tax your intelligence too much. In a loose herd, cues such as body size or aggressiveness may be enough to judge whether you should challenge or steer clear of another individual. In bonded networks, however, you need to know each member’s personal characteristics and those of the friends and relations that might come to their aid. Keeping track of the ever-changing web of social relationships requires considerable mental computing power.

As a reflection of this, there is a correlation between the size of a species’ brain– in particular its neocortex– and the typical size of its social groups. In other words, brain size seems to place a limit on the number of relationships an individual can have. This link between group size and brain size is found in primates and perhaps a handful of other mammals that form bonded societies such as dolphins, dogs, horses and elephants. In all other mammals and birds, unusually large brains are found only in species that live in pair-bonded (monogamous) social groups.

As group size increases so too does the number of relationships that need servicing. Social effort is not spread evenly. Individuals put most effort into their closest relationships to ensure that these friends will help out when they need them. At the same time they maintain the coherence of the group. As a result, social networks resemble a nested hierarchy with two or three best friends linked into larger groupings of more casual friends, and weaker relationships bonding the entire group. This hierarchy typically has a scaling ratio of three– each layer of decreasing intimacy is three times larger than the one before it….


Our social networks can have dramatic effects on our lives. Your chances of becoming obese, giving up smoking, being happy or depressed, or getting divorced are all influenced by how many of your close friends do these things. A good social network could even help you live longer since laughing with friends triggers the release of endorphins, which seem to “tune” the immune system, making you more resilient to disease. So what factors influence the form and function that our social networks take.

In traditional societies, everyone in the community is related to everyone else, either as biological relatives or in-laws. In post-industrial societies this is no longer true– we live among strangers, some of whom become friends. As a result, our social circles really consist of two separate networks– family and friends– with roughly half drawn from each group.

Because the pull of kinship is so strong, we give priority to family, choosing to include them in our networks above unrelated individuals. Indeed, people who come from large extended families actually have fewer friends. One reason we favour kin is that they are much more likely to come to our aid when we need help than unrelated individuals, even if these are very good friends.

Family and friend relationships differ in other important ways, too. One is that friendships are very prone to decay if untended. Failure to see a friend for six months or so leaves us feeling less emotionally attached to them, causing them to drop down through the layers of our network hierarchy. Family relationships, by contrast, are incredibly resilient to neglect. As a result, the family half of our network remains constant throughout most of our lives whereas the friendship component undergoes considerable change over time, with up to 20 per cent turnover every few years.

More than 60 per cent of our social time is devoted to our five closest friends, with decreasing amounts given over to those in the layers beyond, until at the edge of the 150 layer are people we perhaps see once a year or at weddings and funerals. Nevertheless, the outer reaches of our social networks have a positive role to play. The sociologist Mark Granovetter at Stanford University in California has argued that these weak links in our social networks are especially useful in the modern world. It is through this widespread network of contacts that we find out about job vacancies and other economic or social opportunities. More importantly, perhaps, 70 per cent of us meet our romantic partners through these contacts.

Read “Getting Connected” by Robin Dunbar (New Scientist, 4/3/12)

Social capital makes you smarter?

“Spending just 10 minutes talking to another person can help improve your memory and your performance on tests, according to a University of Michigan study to be published in the February 2008 issue of the Personality and Social Psychology Bulletin.

” ‘In our study, socializing was just as effective as more traditional kinds of mental exercise in boosting memory and intellectual performance,’ said Oscar Ybarra, a psychologist at the U-M Institute for Social Research (ISR) and a lead author of the study with ISR psychologist Eugene Burnstein and psychologist Piotr Winkielman from the University of California, San Diego….According to Ybarra, the findings suggest that visiting with a friend or neighbor may be just as helpful in staying sharp as doing a daily crossword puzzle.

“The findings also suggest that social isolation may have a negative effect on intellectual abilities as well as emotional well-being. And for a society characterized by increasing levels of social isolation­a trend sociologist Robert Putnam calls Bowling Alone ­the effects could be far-reaching.”

For further briefing see this link. Podcast with Ybarra here.

For the moment, their evidence is correlational (and relies on pre-existing archival data), and they can’t rule out that it is the intellectual effort generated during the social activities (like playing games) that produces the increase in intelligence or conversely that it is caused by a third unknown common factor. They plan follow-up work to better understand the relationship and any causal mechanism.

P.S. Jane Brody recently reported on this body of research as well in “Mental Reserves Keep Brains Agile
(NY Times, 12/11/07).  Brody reports: “Long-term studies in other countries, including Sweden and China, have also found that continued social interactions helped protect against dementia. The more extensive an older person’s social network, the better the brain is likely to work, the research suggests. Especially helpful are productive or mentally stimulating activities pursued with other people, like community gardening, taking classes, volunteering or participating in a play-reading group.”

How our brain says “I feel your pain”

Intresting Wall Street Journal piece Friday 8/17/07 on the neurological science of empathy. 

A mirror system in the “brain’s motor cortex, which orchestrates movement and muscle control, the cells fire when we perform an action and also when we watch someone else do the same thing. When someone smiles or wrinkles her nose in distaste, motor cells in your own brain associated with those expressions resonate in response like a tuning fork, triggering a hint of the feeling itself.”

It has relevance for social capital as well as autism (scientists are not sure whether autistic individuals lack this important mirror system or whether the mirror system cells receive faulty data).  Studies have also shown that our levels of empathy are higher to those who share our ethnic identity.

Article “How Your Brain Allows You to Walk In Another’s Shoes” (WSJ, Robert Lee Hotz, p. B1, 8/17/07) is avilable here.  And the book Mirroring People is due out next year by Dr. Marco Iacoboni at UCLA.

Donate, then smoke a cigarette?

The Freakonomics blog reports on research of Univ. of Oregon economics professor William Harbaugh and psychology professor Ulrich Mayr that found that “giving to charity can directly stimulate pleasure sensors in the brain.” This parallels some of the research that has come out on the relationship between trust and pleasure sensors as well (oxytocin).