Category Archives: Behavior

Behavior, biology, Egypt Week, science

Egypt Week – Oxytocin and Ethnocentrism

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So, as we approach the end of Egypt Week, we are going to talk about recent paper in PNAS. The researchers examined the effects of oxytocin on the extent to which people exhibit in-group favoritism. They use ethnic markers to indicate in-group versus out-group membership. In this study, which was performed in the Netherlands, the in-group was Dutch and out-groups were German or Arab.

Here’s the bottom line: subjects who were given oxytocin were more likely to favor in-group members relative to placebo-treated subjects. There was also a hint that oxytocin enhanced negative attitudes towards out-group members, but this second effect was quite weak.

Oxytocin causes people to exhibit greater affection and favoritism towards people with whom they share identifying characteristics.

They examined the effects in the context of three different types of experiment. The first was a set of Implicit Association Tests, which asks subjects to identify in-group members by pressing one key and out-group members by pressing a different key. At the same time, individuals use the same two keys to categorize positive and negative words. The test measures how quickly people are able to perform the task when the positive words and in-group members use the same key, and compares this to their performance when positive words use the same key as out-group members.

People are deemed to exhibit in-group bias if they perform the categorization task more quickly when the “in-group key” is the same as the “positive words key” relative to when positive words use the same key as out-group members. The average extra time it takes in the slower arrangement is a quantitative measure of the degree of in-group bias. It was this measure that was enhanced by treatment with oxytocin.

If you’re interested in this sort of test, researchers at Harvard have an online setup, where you can test your own implicit biases about race, sexuality, and other things, and you can see how you compare to the distribution of other people who have taken the test. Check it out here.

The second test looked at “infrahumanization.” It measured how likely subjects were to associate someone with emotions that are commonly perceived to be “uniquely human,” here embarrassment, contempt, humiliation, admiration, hope, and surprise. (This is not a claim that these emotions are actually limited to humans, just that they are often perceived to be so.) Again, people are more likely to associate these with people of their own ethnicity, and treatment with oxytocin appears to enhance this bias.

The third test was a moral dilemma task of the sort that I have described previously. Subjects had to decide whether to take an action that would kill one person in order to save a group of other people. The ethnicity of the one person whom the subject would have to sacrifice was signaled through middle names that were stereotypically Dutch (e.g. Dirk), German (e.g. Helmut), or Arab (e.g. Ahmed). In this test, treatment with oxytocin made the Dutch subjects less likely to sacrifice someone with a Dutch name, but did not affect their willingness to sacrifice Germans or Arabs.

In a March 2010 Playboy interview, “musician” John Mayer bemoaned the fact that he has “a Benetton heart and a fuckin’ David Duke cock.” This may be a consequence of a currently undescribed genetic disorder that produces a highly non-uniform distribution of oxytocin in the body. If true, this disorder will someday be known as “John Mayer Syndrome.” Alternatively, it is possible that he is just a douche. Image via Jezebel.

A lot of studies have investigated the effects of oxytocin on behavior, and it is has previously been shown to enhance trust, cooperativeness, empathy, and prosociality. The authors of this paper interpret their results as saying that oxytocin should not be viewed as a general-purpose feel-good chemical that makes everyone all happy and want to share things. Rather, they argue that these effects may be limited to those with whom the individual shared a common identity. In more complex social settings, they suggest, the in-group bias that is enhanced by oxytocin can lead to actions that are perceived as unfair by out-group members, and can actually enhance between-group conflicts.

Peace be upon you.

De Dreu CK, Greer LL, Van Kleef GA, Shalvi S, & Handgraaf MJ (2011). Oxytocin promotes human ethnocentrism. Proceedings of the National Academy of Sciences of the United States of America, 108 (4), 1262-6 PMID: 21220339

Behavior, biology, Egypt Week, evolution, genetics, genomic imprinting, journal club, science

Egypt Week – Genetic Conflict and Social Dominance

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So, our next scientific Egypt Week post concerns a paper just published in last week’s issue of Nature, where the authors describe novel behavioral effects of the imprinted gene Grb10 in the mouse.

If you’re not familiar, genomic imprinting is the phenomenon where the expression pattern of a gene depends on its parental origin. So, most of your genes come in two copies, one of which came from your mom, and one of which came from your dad. For most genes, the function of the allele, or gene copy, depends just on its DNA sequence. But something like 1% of our genes are imprinted, meaning that they retain a chemical memory of which parent they came from, so that the two gene copies will function differently, even if the DNA sequences are identical.

The most widely accepted theory for the evolutionary origin of gene expression suggests that it is the result of an intragenomic conflict between maternally and paternally inherited gene copies. That is, from a gene’s-eye point of view, natural selection acts differently on maternally and paternally derived alleles.

Many imprinted genes in mammals have growth effects in early development, and these most of these effects are well described by models where selection favors more growth (and a greater demand on maternal resources) when alleles are paternally derived, and less growth (preserving more maternal resources for the mother’s other offspring) when maternally derived.

There is also evidence for large-scale imprinted gene expression in the brain, and evidence that these imprinted genes may have substantial effects on cognition and behavior. We are still at the early stages of describing these effects, and at even earlier stages of understanding the relevant evolutionary pressures.

Elsewhere on this blog, I have begun writing a series of primers on genomic imprinting, links to which can be found here, if you are interested in more background.

Today’s paper describes the effects of the two parental knockouts of the Grb10 gene. Grb10 is a particularly interesting imprinted gene, because it is maternally expressed in many peripheral tissues, but paternally expressed in the central nervous system. So, when you knock out the maternally inherited copy, you get a complete loss of function in the periphery, but don’t impact Grb10 expression in the brain. Conversely, when you knock out the paternally inherited copy, you lose gene function in the brain, but leave expression in the periphery unaffected.

The phenotype of the maternal knockout is more or less what is expected in terms of growth effects, and is consistent with previous studies of this gene. Theory predicts that if a growth-related imprinted gene is maternally expressed, it likely functions as a suppressor of growth. When the maternal copy of Grb10 was knocked out, the result was overgrowth, due to the loss of this growth-suppressing function.

The knockout of the paternally inherited results in a behavioral phenotype associated with increased social dominance, as indicated by two specific behaviors. The first dominance behavior was observed in a “tube test.” In this test, two mice who don’t know each other are forced to encounter each other in a tube. In this setting, the knockout mice are less likely to back down than the wild-type (normal) mice are.

The second observation was an increase in allogrooming and barbering. Let’s pause for a moment to talk about what that means. Allogrooming is where one individual grooms another individual (in contrast to autogrooming, where you groom yourself). Barbering is where the grooming gets out of hand, and the groomee gets big bald (and sometimes bruised and bloody) patches.

Now, intuitively, you might assume that grooming behavior is submissive, like the handmaid combing out the princess’s hair. In mice, at least, it’s not like that. If you have a pet mouse, and it is grooming you, it is actually being dominant. It’s more like when you sit your little sister down in a chair and put makeup on her – the goal is NOT to make her look good. And, if you are feeling really mean, you give her a haircut, too.

The researchers argue that the behavioral effect is specific to social dominance, as tests designed to look at anxiety, locomotion (moving), olfaction (smelling), and aggression all found no differences between these knockouts and wild-type (normal) mice.
A conflict-based interpretation of these behavioral results would suggest that, for some reason, maternally inherited genes place a greater premium on establishing social dominance than do paternally inherited genes. (In the nervous system, the gene is paternally expressed, and knocking it out increased dominance behaviors. This implies that the gene normally acts to limit dominance behaviors.)

A bemedallioned Hosni Mubarak helps to illustrate the intragenomic conflict over social dominance behaviors. Natural selection favors alleles that enhance socially dominant behaviors when they are maternally derived, but limit socially dominant behaviors when paternally derived. The study was performed in mice, and it is important to note that the patterns of imprinted gene expression can vary among species, so we can not extrapolate from these results to the influence of Grb10 on human cognition and behavior. However, mice and rats are closely related, so we are probably safe extrapolating to Mubarak.

The next question is why would alleles favor more socially dominant behaviors when maternally derived? Fundamentally, at this point we have no idea. This is where the modeling has to come in. In this type of situation it is always possible to come up with a host of possible explanations, all of which sound plausible, and all of which would predict that a paternally expressed gene would limit dominance. The key thing is to model each of those explanations formally, so that we know what key ecological and demographic factors underlie the explanation. Then, we find other species where those factors differ, and examine the imprinting status and phenotypic effect of Grb10 in those species.

For the less politically oriented, the intragenomic conflict over social dominance is like this. Nadya “Octomom” Suleman is like your maternally inherited genome, while the guy with the moustache and the milk bottle is like your paternally inherited genome. Image from the Daily Mail.

Peace be upon you.

Garfield AS, Cowley M, Smith FM, Moorwood K, Stewart-Cox JE, Gilroy K, Baker S, Xia J, Dalley JW, Hurst LD, Wilkinson LS, Isles AR, & Ward A (2011). Distinct physiological and behavioural functions for parental alleles of imprinted Grb10. Nature, 469 (7331), 534-8 PMID: 21270893 [1]

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[1] Disclosure: I didn’t really intend for Egypt Week to devolve into blog-posts-about-papers-by-collaborators-of-mine week, but there you have it. I have an ongoing collaboration with Anthony Isles, and know some of the other authors.

Behavior, biology, culture, journal club, math, science, scientific misconduct

Mathematicians and Mongeese: Peeing to Defend Territory? or Mates?

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So, you may have heard about Tihomir Petrov, the math professor at Cal State, Northridge who was arrested for urinating on his colleague’s office door. Campus security got video footage of Petrov in the act when they set up video cameras following the discovery of “puddles of what they thought was urine.”

You may be asking yourself, what the heck was this dude thinking? How should we interpret the behavior of this Homo mathematicus (not that there’s anything wrong with it) specimen?

What Professor Petrov was probably thinking.

Fortunately, once again, Science!™ has an answer for you. Urine is commonly used as a scent marker to deter competitors. But deter them from what? Traditionally, it has been assumed that scent marking is primarily used to defend territory against intruders, thereby safeguarding resources such as food and space. However, some recent studies have suggested that scent marking may be used to defend mates and mating opportunities. One of the difficulties in studying such a question, however, is that in many systems, competitors for territory and competitors for mates are the same individuals.

A recent study by a group of researchers in the UK, Uganda, and Switzerland have attempted to separate out these two forms of competition in a study of the wild banded mongoose. This species lives in large social groups that share a territory. Thus territorial competition occurs primarily between different social groups, whereas competition over mates occurs primarily within groups.

“Anal gland secretion (AGS) and urine samples were collected under anaesthesia during routine trapping events”  Image licensed under creative commons from Mike Rohde’s Flickr photostream.

The researchers found that the mongoose populations marked uniformly throughout their territory, and did not appear to increase the frequency of marking in those regions where two territories overlapped. This suggests that, in this species at least, defense of mates and mating opportunities represents a major contribution to scent-marking behavior, perhaps more so than territorial defense.

So, can we extrapolate from the behavior of the wild banded mongoose to the behavior of wild banded mathematician Tihomir Petrov? Of course we can! Should we extrapolate? Absolutely not! But, here at Lost in Transcription, we’re all about the possible, so here is the take-home message. Castle and Beckett should look beyond professional disputes between the two mathematicians. They need to be looking at the love-triangle angle (Love angle4?) for motive.

Alternate theory: As Northridge is, like, the pr0n capital of the country, Petrov might not have been the original urinator. When he saw that the cameras had been set up, he might have assumed that he had been cast in a movie, and that peeing on the floor was what was expected of him. Just sayin’.

Jordan, N., Mwanguhya, F., Kyabulima, S., Rüedi, P., & Cant, M. (2010). Scent marking within and between groups of wild banded mongooses Journal of Zoology, 280 (1), 72-83 DOI: 10.1111/j.1469-7998.2009.00646.x

Behavior, culture

Naming Advice for New Parents

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So, you’re having a baby. There’s one rule, really. Are you listening?

Don’t give your kid the middle name “Lee.”

Here’s the latest “*Lee*” in the news, Ricky Lee Kalichun:

from the Evansville Courier & Press, via Geekologie

Broke into ex-roommate’s apartment. To get back his video games. With a sword.

He was wearing a camouflage jacket, and camouflaged his face as well, with a marker. Maybe he was hoping to be mistaken for one of Jesse James’s girlfriends.

Now, I’m glad that your Grampa Lee was a World War II hero and all, but, really, just – just don’t.

Behavior, culture, Politics

On aging, conservatism, and experimental economics

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So, it is standard conventional wisdom that people are liberal when they’re young, and conservative when they’re old. To the extent that we interpret “liberal” as “eager for change” and “conservative” as “against change,” this trajectory is only natural. Especially in the modern world, where things are changing all the time, it may simply come down to a difference in experience: you’re less likely to pine for the way the world was thirty years ago if you weren’t alive thirty years ago.

But what I am really interested in here is the apparent trend where people become more conservative with respect to economic policies. In this context, the argument about familiarity does not seem to hold. In the United States, the government’s economic policies have been trending more conservative for decades, and the familiarity argument would predict that older people should be, on average, more liberal. However, there is a different aspect of familiarity that may be relevant, as it pertains to our beliefs about human nature.

A key aspect of the economic debate between liberals and conservatives is a difference in the assumptions they make about how people will behave when left to their own devices. If you will forgive me for painting complex things with a simple brush, the cartoon versions of these are something like this. Conservatives believe that people are inherently self-serving and lazy, and will work hard only if they are given tangible incentive to do so. From this perspective, progressive tax structures and government programs like welfare and social security are problematic because they take away the incentive to earn money. Liberals, by contrast, believe that everyone is trying hard, that inequality comes largely from societal structures that are beyond individuals’ control, and that people should not be punished for the inherent unfairness of society (except maybe those at the top of the pay scale, who have benefitted most from those inequalities).

Now, the most obvious difference between young people and old people is that old people have a lot more experience with other people than young people do. That is, we tend to start out with positive views about human nature, but over time we interact with more and more people, they disappoint us, and we become progressively more cynical. Many conservatives see this as evidence in favor of their position: we start naive, and become conservative when we learn what people are actually like. However, I want to suggest a different explanation, having to do with asymmetries in how we perceive positive and negative deviations from our expectation. Intuitively, this comes down to the fact that we notice whenever we get stopped by a red light, but often don’t notice when we hit a green light. Therefore, we perceive that stoplights are red more often than they actually are.

This also happens in the economic domain, as has been extensively documented by experimental economists in a variety of “public goods” games. The basic structure of these games is as follows. You have a group of people, say 10, and you give each of them some money, say $10. Each person can then contribute a fraction of their $10 to the “pot.” The money in the pot is the multiplied by some factor, say 5, and then distributed equally among the ten players. So, if no one contributes anything, everyone gets to keep the $10 they were given at the beginning. If everyone contributes the full $10, the pot has $100, which is multiplied by 5 to give $500, which is distributed back to the players, and everyone walks away with $50.

The ideal thing for the group as a whole is for everyone to contribute the maximal amount. However, the ideal thing for the individual is to contribute nothing (and to hope that everyone else contributes the maximum). For example, if I contribute nothing, and everyone else contributes $10, I walk away with $55, and everyone else walks away with $45. If I contribute $10, and no one else contributes anything, I’ll get $5, and everyone else will get $15. From an “economic rationality,” “Nash equilibrium” perspective, the thing to do is contribute nothing. However, this is not what happens in practice.

In a wide variety of experimental setups, what people actually do is contribute about 50% of what they are initially given. So, the typical outcome in our experiment would be that everyone contributes about $5, which makes $50 in the pot, which is multiplied to $250, and everyone walks away with $30 (the $5 they kept plus $25 from the pot). Across a broad range of cultures, ages, quantities of money, etc., people come into these experiments with a somewhat liberal perspective, as they seem to both trust the good will of the other players, and care about the results for the group as a whole.

However, if we play the game over and over again, an interesting thing happens: the average contribution gradually declines, until eventually, no one is contributing anything to the pot. Based on interviews with the participants in these games, economists believe that they understand this trend. Let’s say that one person contributes $5, which is the average among the group, but some people contribute $4, and some $6. This person will not really think about the people who gave $5 of $6, but will think a lot about the people who gave $4, get pissed off, and reduce their contribution in the next round. While it is mathematically trivial that people, on average, contribute the average amount to the pot, it seems to be psychologically true that people perceive themselves on average as having made an above-average contribution.

What I think is that something analogous happens over the course of the lifetime of an individual. We meet some people who are hard working, and some who are lazy, but there is this perceptual bias that means that the lazy, selfish people we meet weigh more heavily in our developing opinions about “what people are like.”

The other interesting finding from these experiments is that it is remarkably easy to reset the spiral of cynicism. If you take the participants out of the room, give them a cup of coffee, and let them use the bathroom, when they go back in, they often go right back to contributing 50% on average. So, note to Democratic lawmakers, if you can figure out how to let the country drink a collective cup of coffee and use the collective bathroom, you may find a dramatic increase in support for social programs and a progressive tax structure.