Month: May 2008

The link between attractiveness and facial symmetry seems to hold across both black and white faces, but also in non-human primates, according to a study just published in the open-access science journal PLoS One.

One of the most striking studies in sex and symmetry research isn’t mentioned, however. A 1995 study found that the likelihood of female orgasm during sex was related to the extent of bodily symmetry in the male partner.

The study was led by biologist Randy Thornhill and recruited 86 young couples who completed a number of relationship questionnaires, including one on how often the female partner orgasmed during sex. The males then had their bodies measured and assessed for how much one side differed compared to the other – a measure of bodily asymmetry.

In the final analysis neither the male’s age, wealth, social skills, physical attractiveness or relationship style predicted the frequency of female orgasm. Only male bodily symmetry was statistically associated with the chance of the women climaxing during sex.

The researchers thought that maybe women who have more orgasms, or who are just more sexual, simply get the more symmetrical (maybe hotter) guys. But when they looked at frequency of orgasm outside copulation (such as during oral sex or masturbation), the relationship to male symmetry disappeared, suggesting that this wasn’t the case.

This study, and the new study published in PLoS One, also suggested that symmetry was associated with more masculine features generally – a bigger body in the orgasm study, and a more typically male face in the PLoS research.

The evolutionary explanation suggested by the authors is that female orgasm during copulation may make pregnancy more likely, so it’s an adaptive strategy to increase fertility when making love to males with genes more likely to lead to healthy children.

How orgasm increases with body symmetry is not clearly understood, though. The authors speculate that female perception of a highly symmetrical male might psychologically prime sexual arousal, but the mechanism is left largely to guesswork.

Link to PLoS One study on attractiveness and symmetry (via Anthro).
Link to abstract of orgasm and symmetry study.

The New York Times has a concise article that discusses adolescents who self-harm through cutting, burning or deliberately damaging themselves. Self-harm is curious because it is one the most psychologically complex of behaviours and yet we have a simple but largely inaccurate cultural stereotype – attention seeking teenagers.

There are many, many types of self-harm, some more culturally acceptable than others. Self harm is often accepted as part of fashion or ritual (piercings, scarring), or can be due to genetic abnormalities (e.g. Lesch-Nyan syndrome), or as a result of learning disabilities or brain injury.

It can be because of delusional or psychotic ideas; OCD type urges, like hair pulling or skin picking, which people often want to resist but can’t; or can be an indirect result of other difficulties, such as damaging the body through drugs, alcohol, or an eating disorder.

The type discussed in the article, and what we normally think of in our cultural stereotype, is often an adolescent or young adult who cuts or burns themselves.

The motivations vary, and yes, a minority do give ‘wanting attention’ as a reason. Sometimes this is a learnt response when they’ve been in an environment where the only time they have been given any care or attention is when they’ve damaged themselves.

However, the vast majority try their best to hide what they do and it can be a source of significant shame.

As noted in a recent review on the area, this group tends to use self-harm as a way of managing strong emotions and cutting is associated with a build-up of tension and the feeling of relief at the time of committing the act.

People who self-harm are more likely to be depressed, impulsive and poor at problem-solving and self-harm is often a way they’ve found, at least temporarily, to control otherwise overwhelming emotions.

Although the risk of suicide is increased in adolescents who self-harm, only a minority will go on to kill themselves. Just over 1% in a recent study with a 26 year follow-up.

There’s still not a great deal of research on which are the best treatments with the biggest reviews being inconclusive, but recent findings suggest that self-harming problems can be treated with psychological therapy.

Link to NYT article on self-harm.

A fascinating study on the social trends in neuroscience research has found that New York is happening but Boston is hot, dementia researchers are the most influential, high-level processes are hip and that neuroscientists need to practice professional ‘birth control’ to avoid mass starvation.

The results come from a paper just published in PLoS One that used the abstracts from five years’ worth of Society for Neuroscience annual conference presentations to map out emerging trends in brain research.

The study did a series of ‘bibliometric‘ analyses. That is, it used software that looked for links between people, topics, geographical location and other points of interest over time by analysing the text of presentation summaries.

The SfN conferences always happen in the States, so there’s certainly a bias, but they’re generally considered the most important international meeting of the year, so the paper is full of gems about neuroscience now and in the future. I’ve pulled out a few below.

The global “hubs” for neuroscience research seem to be concentrated in the northeast region of the United States (Boston, New York, Philadelphia, Baltimore/DC vicinity), Southern California, Tokyo, Montreal, and London.

New York City consistently ranks as the top producer of neuroscience research, but when population size is included, Boston and Baltimore come out particularly well, as they rank high in both the raw number of authors and per population participation in SfN meetings.

There has been a shift in general scientific interest from ‘low-level’ research on cellular processes such as ion channels, synapses, and cell membranes, towards more ‘high-level’ research on things like vision, movement, and neuroimaging.

A useful graph shows words which have decreased in frequency in the research summaries over the years on the left, and words increasing in frequency on the right.

In a social network analysis, the neuroscientists with the largest betweenness centrality, a measure of influence over the network, were not necessarily those with their name on the largest number of research presentations.

Interestingly, most of these scientists conduct research in the field of neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, and the authors of the study speculate that this may be because the area is well funded and that it involves a diverse range of research techniques. Therefore, the researchers are likely to be connected with many others in the field.

A cluster analysis of themes looked at which research areas formed coherent groups. It’s interesting to compare SfN’s traditional classification of topics with the results of the analysis which found spontaneous groupings.

While there is some overlap, areas like ‘pain and trauma’, the ‘behaviour of song birds’ and ‘sleep’ seem to have formed strong groupings by themselves.

In terms of the population shift in neuroscience, about 60% of researchers seem to be ‘transitory’, probably students or outside collaborators who don’t remain in the field for long.

However, the growth of the neuroscience community has been massive, while the total funding has remained steady.

The authors suggest that like in any population boom, research institutions should use the equivalent of ‘birth control’ to keep numbers down, otherwise they’ll be more people than jobs, and lots of people will be work-starved.

Starvation, of course, regulates a population, although is a rather painful process for those who expire due to lack of resources.

Link to full text of PLoS One paper on neuroscience trends.

Two recently published articles on inter-group violence highlight the how the cycle of vengeance is remarkably similar across two different cultures: one in tribal peoples from New Guinea, the other in street gangs from Chicago.

In an article for The New Yorker Jared Diamond writes about the cycles and social customs surrounding vengeance in New Guinea by examining how one Handa tribesmen sought to exact revenge on another tribe for the death of his uncle.

The social customs about what counts as vengeance, how and whom it may be exacted upon are complex, but it’s interesting that Diamond concludes that the desire for vengeance is a powerful motivation (ranking alongside love, anger, grief, and fear) which feeds the cycle of retribution even past the point where the original cause of the conflict has been lost in the sands of time.

A similar theme is echoed in an article published in today’s New York Times on gang violence in Chicago. It focuses on a project called CeaseFire started by epidemiologist Gary Slutkin.

The project uses an interesting method which thinks of violence like a disease which can be transmitted through vengeance, and so applies an approach taken from disease prevention models to try and stop the spread of shootings.

Slutkin employs mostly ex-members of the Chicago underground who know both the streets and the players to intervene and mediate disputes when violence has flared on when the situation seems ready to explode.

The idea, just like in clinical epidemiology, is to target the most ‘infected’ members to reduce transmission – in this case, by engaging those causing the most violence and cooling the need for vengeance.

After a quick search, there seems to be remarkably little research on the role of vengeance in violence (although almost all supports its role).

This tends to parallel the research into violence in general. As one of the biggest killers in the world, I’m always struck by how little attention it gets.

Link to Jared Diamond article ‘Vengeance is Ours’.
Link to NYT article ‘Blocking the Transmission of Violence’.