Chimps 1, Humans 0

by Jason on 16 May 2012

At the recent The Biological Basis of Preferences and Behaviour conference, Colin Camerer presented the results of a paper concerning work he and his co-authors had been doing with chimpanzees at the Primate Research Institute at Kyoto University.

At the beginning of the presentation, Camerer showed a couple of videos of experiments dealing with the working memories of chimps. The videos show subjects undergoing a test in which they see five numbers briefly flash on a screen before the numbers are covered with white boxes. The subject must then press the boxes in the order of the numerals. Of the three videos below, the first is a human subject, the second and third a chimpanzee. The chimpanzee (Ayumu) is receiving pieces of apple for each correct answer, which he is collecting from the lower right of the screen.

While the contrast between the first two videos is striking, the third video shows the power of the snapshot that Ayumu has in his mind.

More on this work can be found on the PRI website and in Current Biology. I’ll post on the substance of the paper presented by Camerer, concerning the game theoretic abilities of chimpanzees, when it is published (hopefully) in the not too distant future.

Human

Chimp

Distracted chimp

*Jeff Ely beat me to putting up these videos over at Cheap Talk, but since I already had the post put together, it’s still worth a share.

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While we wait for the genoeconomics revolution

by Jason on 15 May 2012

Following the publication of two new articles in the Annual Review of Economics and PNAS (my summary here), genoeconomics has been getting some press. From the Boston Globe:

But for all their throat-clearing and the cold water they feel compelled to throw on their work as they introduce it to the general public, they are confident that it’ll eventually be possible to match up patterns in a person’s genome with patterns of financial behavior. Perhaps parents could be alerted if their kids have genes that incline them to impulsive spending or wildly risky investments, Benjamin said. Or perhaps policy makers could use genetic information about a particular population—say, cigarette-smokers or alcoholics—in order to craft policy more effective at encouraging some behaviors and discouraging others.

While genoeconomics might provide exciting results, some of the information that is likely to emerge is already available to be used. We know from twin studies that patterns of financial behaviour are heritable. If a parent knows they are financially reckless, this can provide a probability of that behaviour for their child. You should worry about your child smoking or being an alcoholic if you have those characteristics yourself. We can obtain further information from the behaviour of siblings or other relatives. We do not need to wait for genoeconomics to deliver results before we can make inferences about genetically influenced behaviour.

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Maladaptive ideas

by Jason on 14 May 2012

Following the Consilience Conference and some suggestions for additions to my reading list, I have been convinced to read some more work by Robert Boyd and Peter Richerson. I’ve started with The Origin and Evolution of Cultures.

One quote in the introduction caught my eye:

[A]cquiring adaptive information from others also opens a portal into people’s brains through which maladaptive ideas can enter—ideas whose content makes them more likely to spread, but do not increase the genetic fitness of their bearers. Such ideas can spread because they are not transmitted as genes are. For example, in the modern world, beliefs that increase the chance of becoming an educated professional can spread even if they limit reproductive success because educated professionals have high status and thus may likely be emulated. Professionals who are childless can succeed culturally as long as they have an important influence on the beliefs and goals of their students, employees, or subordinates. The spread of such maladaptive ideas is a predictable by-product of cultural transmission.

While I might characterise the maladaptation differently – it is not being a professional in itself that limits reproductive success – this approach contrasts with the economic explanation. Economists usually frame the fertility decision as a rational quality-quantity trade-off. In addition to the usual economic assumption of rationality concerning the pursuit of an objective, there is also an assumption that the objective itself (fitness in a biological sense) is rationally chosen. There is no maladaptation, and I suspect this is the cause of some of the difficulty the economic approach to the problem has faced.

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The genetic architecture of economic and political preferences

by Jason on 11 May 2012

Evidence from twin studies implies that economic and political traits have a significant heritable component. That is, some of the variation between people is attributable to genetic variation.

Despite this, there has been a failure to demonstrate that the heritability can be attributed to specific genes. Candidate gene studies, in which a single gene (or SNP) is examined for its potential influence on a trait, have long failed to identify effects beyond a fraction of one per cent. Further, many of the candidate gene results fail to be replicated in studies with new samples.

An alternative approach to genetic analysis is now starting to address this issue. Genomic-relatedness-matrix restricted maximum likelihood (GREML – the term used by the authors of the paper discussed below) is a technique that looks to examine how the variance in traits can be explained by all of the SNPs simultaneously. This approach has been used to examine height, intelligence, personality and several diseases, and has generally shown that half of the heritability estimated in twin studies can be attributed to the sampled SNPs.

A new paper released in PNAS seeks to apply this approach to economic and political phenotypes. The paper by Benjamin and colleagues shows that around half the heritability in economic and political behaviour observed in behavioural studies could be explained by the array of SNPs.

The authors used the results of recent surveys of subjects from the Swedish Twin Registry, who had their educational attainment, four economic preferences (risk, patience, fairness and trust) and five political preferences (immigration/crime, foreign policy, environmentalism, feminism and equality, and economic policy) measured. The GREML analysis found that for one economic preference, trust, the level of variance explained by the SNPs was statistically significant, with an estimate of narrow heritability of over 0.2. Two of the political preferences, economic policy and foreign policy, had narrow heritability that was statistically significant, with heritability estimates above 0.3 for each of these. The authors noted that as the estimates are noisy and GREML provides a lower bound, the results are consistent with low to moderate heritability for these traits.

Educational attainment was also found to have a statistically significant result, although the more precise measurement of educational attainment and the availability of this data across all subjects made that result more likely.

This result is corroboration of the evidence from twin studies and provides a basis for believing that molecular genetic data could be used to predict phenotypic traits. However, one interesting feature of the GREML method of analysis is that after conducting this analysis with one sample, the data obtained does not assist in predicting the traits for someone out of the sample. This technique shows the potential of molecular genetic data without directly realising those results.

As a comparison, the authors examined whether any individual SNPs might predict economic or political preferences, but found none that met the significance test standard of 5×10-8. Such a high level of significance is required to reflect the huge number of SNPs that are being tested.

The authors also conducted the standard comparison between monozygotic (identical) and dizygotic (fraternal) twins, which resulted in heritability estimates consistent with the existing literature, although with a much larger sample than typically used. Looking through the supplementary materials, the major surprise to me was that the twin analysis suggests that patience has low heritability, with a very low correlation between twins and almost no difference between monozygotic and dizygotic twins (in fact, for males, dizygotic twins were more similar).

The authors draw a few conclusions from their work, many which reflect the argument in a Journal of Economic Perspectives article from late last year. The first and most obvious is that we should treat all candidate gene studies with caution. Hopefully some journals that insist on publishing low sample size candidate gene studies will pay attention to this. Where they are going to be conducted, you need very large samples, and significantly larger than are being used in most studies being published.

Meanwhile, they are still hopeful that there can be a contribution from genetic research, particularly if the biological pathways between the gene and trait can be determined. This might include using genes as instrumental variables or as control variables in non-genetic empirical work. The use as instrumental variables does require, however, some understanding of the pathways through which the gene acts as it may have multiple roles (that is, it is pleiotropic). They also suggest that the focus be turned to SNPs for which there are known large effects and the results have been replicated.

On element of analyses of political and economic preferences that makes me slightly uncomfortable is the loose nature of these preferences. For one, the manner in which they are elicited from subjects can vary substantially, as can the nature of the measurement. Take the 2005 paper by Alford and colleagues on political preferences, which canvassed 28 political preferences. Many of the views are likely to change over time and be highly correlated with each other. And why stop at 28?

As a result, it may be preferable to take a step back and ensure that data on higher level traits are collected. I generally consider that IQ and the big five personality traits (openness, conscientiousness, agreeableness, extraversion and stability) are a good starting point and are likely to capture much of the variation in political and economic preferences. For example, preferences such as patience are likely to be reflected in IQ, while openness captures much of the liberal-conservative spectrum of political leaning. Starting from a basis such as this may also give greater scope for working back to the biological pathways.

The Social Science Genetics Association Consortium is doing some work in harmonising phenotypes across large samples. Hopefully their work will lead in this direction.

Benjamin DJ, Cesarini D, van der Loos MJ, Dawes CT, Koellinger PD, Magnusson PK, Chabris CF, Conley D, Laibson D, Johannesson M, & Visscher PM (2012). The genetic architecture of economic and political preferences. Proceedings of the National Academy of Sciences of the United States of America PMID: 22566634

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Game theory and the peacock’s tail

by Jason on 9 May 2012

Over at Cheap Talk, Jeff Ely has posted on a presentation by Balazs Szentes at The Biological Basis of Preferences and Behavior conference. Ely writes:

Balazs Szentes stole the show with a new theory of the peacock’s tail.  …

Suppose female peacocks choose which type of male peacock to mate with: small or large tails. Once the females sort themselves across these two separate markets, the peacocks are matched and they mate.

The female peacocks are differentiated by health, and within a peacock couple health partially compensates for the disadvantageous tail. In the model this means that healthy females who mate with big-tailed peacocks will produce almost as many surviving offspring as they would if they mated with peacocks without the disadvantage of the tail. …

Consider what happens when a small-tailed peacock population is invaded by a mutation which gives some male peacocks large tails. Since female peacocks make up half the population of peacocks there is now an imbalance in the market for small-tailed peacocks. In particular the males are in excess demand and some females will have trouble finding a mate.

On the other hand the big-tailed male peacocks are there for the taking and its going to be the healthy female peacocks who will have the greatest incentive to switch to the market for big tail. The small cost they pay in terms of reduced quantity of offspring will be offset by their increased chance of mating. The big tails have successfully invaded.

Szentes’s theory illustrates the mixed feelings I expressed in my recent post about some of the presentations at the conference. The model underlying the theory is clever and interesting, but Szentes’s focus is more on the game theory than the evolutionary problem that the model is proposed to address. Szentes’s proposed explanation of the peacock’s tail is unlikely to be right, and while the model is insightful, I am not sure it offers any insight into the problem at hand.

This is because core assumptions of the model do not hold. The model requires an assumption of monogamy, which peacocks are not. As for most males with ornaments, the peacock’s tail is used to attract multiple partners to make up for the handicap that the ornament imposes (as the more established theory suggests). The model also assumes that the males are indifferent as to who they mate with (despite being monogamous), with high quality females unable to attract male interest above that of females of low quality.

Without those assumptions, the findings derived from the model no longer hold. In some respects, the sexes in the model appear backward, as lack of males willing to give sperm is not an issue in most species. The low investment by males makes females the scarce resource.

I expect that these issues are of less concern to Szentes (or, based on his post, Ely) than they are for me, as his interest lies more in the model than its particular application. Szentes appeared to be aware of these critiques when they were raised at the conference.

However, it would be useful if the model was framed in a manner where the basic assumptions hold for the phenomena sought to be explained. But if the model is not useful in explaining the peacock’s tail, what situation might the model describe? Instead of talking of disadvantaged males with tails, could we talk of low quality males and use the model to explain the persistence of low quality males in a population? This is an interesting model looking for a use.

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Rubin’s Darwinian Politics

by Jason on 7 May 2012

The application of evolutionary biology to politics and policy spans the political spectrum. From Peter Singer’s A Darwinian Left to Larry Arnhart’s Darwinian Conservatism to Michael Shermer’s libertarianism, there is something in evolutionary biology for everyone.

For me, one of the best of of these applications is by Paul Rubin in Darwinian Politics: The Evolutionary Origin of Freedom. While the arguments lead to conclusions that reflect Rubin’s political leanings, the book reads as though the evidence shapes the result and Rubin gives the evidence fair consideration.

Rubin’s basic position is that the political institutions of Western nations, and particularly the United States, are the best match with evolved human preferences. Humans seek freedom from dominance, with Western society maximizing that freedom. Political freedom allows citizens to form a reverse dominance hierarchy, with public pressure, wealth and constitutional frameworks limiting the ability of Western governments to exercise power. Western institutions also provide a framework that limits negative consequences of our evolved psyche, as the move away from kin based groups reduces xenophobic behaviour.

Rubin does not suggest, however, that humans are perfectly matched to our current environment. Rather, he argues that the current institutional frameworks do a good job of working around them. For example, one of the main threads of Rubin’s argument is that humans have moved from an evolutionary history of living in consumption hierarchies, which are effectively zero sum, to a world of productive hierarchies, whereby participation in hierarchies can boost production and be good for all involved. Humans do not always distinguish between the two (nor academics as Rubin makes clear), and as a result, envy may result as someone acts as though they are still in their zero sum world.

Rubin sees the best political framework as one that can deal with this tendency to envy while not damaging the productivity of the hierarchy. Rubin addresses these concerns through a couple of threads. One is to note that in a free society, movement between hierarchies is possible and people are likely part of many hierarchies. They will not always be at the bottom. However, Rubin paints an overly rosy picture (he should paint a rosy one – it just needs some tempering), as some hierarchies are more important than others and mobility is not a complete solution. If you are at the bottom of an employment hierarchy, your choice is likely to be which hierarchy you wish to be at the bottom of. As shown in the famous Whitehall studies, being at the bottom of a productive hierarchy may have costs (not that I implying that Whitehall itself is a productive hierarchy).

A more interesting points is when we move from utility to fitness. Rubin writes:

If an individual is highly productive and creates much wealth, social as well as private benefits will be generated; a productive individual will not normally absorb the entire surplus he will create. Thus, utility or wealth maximisation would imply that all will benefit from such increased productivity and should encourage it. However, if the added productivity is used to engross additional females, or if tastes evolved in an environment where this occurred, then in fact others will become less fit, although wealthier. In this sense, fitness and utility maximisation conflict. This may explain why many utility functions seem to contain elements of envy, even though envy is counterproductive with respect to consumption of wealth maximisation.

Rubin’s primary solution to this, already implemented throughout the West, is monogamy. Each man can only monopolise one female regardless of wealth. While monogamy undoubtedly acts as a reproductive leveler, Rubin’s analysis attempts to finesse his case too much. Despite monogamy in Western societies, there is still a large proportion of men at lower socioeconomic status who fail to attract a mate. Higher status women simply choose not to mate with them and lower status women have other avenues of seeking financial support. For example, over 40 per cent of Australian men between the ages of 40 and 44 and with incomes below $20,000 per year remain unpaired. This contrasts with just over 10 per cent of men of that age group with incomes over $83,000 per year. Monogamy levels the reproductive playing field but it is not completely flat.

For each of these points, Rubin is essentially right in his argument that productive hierarchies are beneficial and that monogamous societies are more stable and level the reproductive playing field. However, there is still a bottom of the hierarchy and consequences to it, and there will always be some degree of pushback due to this.

To assist those at the bottom, Rubin notes the evolved altruistic preferences for assisting those in need. As a result, some wealth redistribution may be supported. But if the focus moves from supporting the poor to clipping the rich, the output of productive hierarchies may be threatened. Further, Rubin considers that social support will remain popular as long as it is not overexposed to free-riding, with humans having strongly refined senses to spot those who are not pulling their weight.

Rubin’s least libertarian finding, apart from his implied support of restrictions on polygamy, relates to restrictions on drugs and other “anti-social” activities. Rubin argues that if consumption of these goods and activities is a form of competition between young males to signal status, restrictions on their use will be required to prevent above optimal use. While Rubin considers that the need to maintain a society’s prime age men at fighting strength is weaker than in our evolutionary past, a case can still be made for this form of control. It was interesting that Rubin chose to use a signaling argument at this point as he does not address the role of signaling in most of his analysis, such as in his discussion of “altruistic” gifts of game in ancestral societies or donations to charity.

Overall, Rubin’s arguments are clear, transparent and generally persuasive. It was an omission by oversight from my economics and evolutionary biology reading list, as I last read it a number of years ago, but it has now been included (thanks to Eric Crampton for the nudge).

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The Biological Basis of Preferences and Behaviour conference

by Jason on 6 May 2012

I have just attended The Biological Basis of Preferences and Behaviour conference at the Becker Friedman Institute at the University of Chicago. It was a good conference with some high quality presentations, and I will post on some of them over the next few weeks once I digest the presentations and papers (or they exit embargo).

In the meantime, the conference has triggered some thoughts on how economics will contribute to the evolutionary sciences, and how biology will be integrated into economics.

Most work generated in the economic field concerned with the evolution and biological basis of preferences uses beautiful (to some beholders) but complicated mathematical models. As a grossly generalised illustration, most presentations at the conference consisted of multiple slides of equations and proofs. Many questions and clarifications were required as the presenter progressed through the slides. The presentation usually ended with an attempt to explain the intuition of the model in plain language.

After being walked through one of these models, the first question to ask is whether the finding of the model might be true (noting the problems of defining truth). Are the assumptions even ballpark realistic? Is there any evidence that the process described in the model occurs or has occurred?

The next question is about insight. Did this model, even if not “true”, provide useful insight into the process or phenomena being explored?

Finally, does the model communicate the idea in a manner that will be understood by people who might care about or should know about the work?

My impression was that most of the conference presentations fell at the first two hurdles. Where they did clear them, the product of the research is unlikely to be consumed outside of a very small circle, generally comprising of other members of the field. Mathematical models are an excellent way to communicate to some people (my impression is that many in the conference audience prefer this approach), but simple, verbal explanations are the way in which most communication occurs. Where maths is used, it should be as simple as possible to illustrate the point. Even though I work directly in the area, I will not invest the effort to understand the models from most of the presentations. Other audiences are unlikely to either.

This is, of course, a broader issue through much of economics, where the incentives push researchers towards beautiful but complicated models. Generally, these models will not be subject to testing and as a result, do not face the threat of being discarded if they are not supported by the empirical evidence. Having robust mathematics that supports the story being told has greater weight than the truth of the model or the manner in which it might communicate an insight. There is little direct competition between models.

In contrast, at last week’s Consilience Conference there was barely an equation in sight. The presentations provided me with a mountain of ideas that I have been communicating in various ways to people ever since. Those presentations from this week’s conference that were based on a detailed mathematical model, while providing some fodder for thought, are unlikely to feature in many conversations. I am not sure the models presented are true or insightful, and even where they are, my first thought is how to come up with a different way of communicating the point. My posts over the next couple of weeks will largely feature those presentations that were the exception to the rule.

Having now dug a myself into a hole through some broad, over-generalised criticism, this critique is not to say that there are no useful and important ideas coming out of this work. My economics and evolutionary biology reading list contains a sample of what I consider to be some of the more important contributions. Rather, my critique reflects my instinct that the field will remain a world unto itself, without being a significant contributor to the congruence of biology and economics. Research into the biological basis of preferences and behaviour has massive potential to affect the broader field of economics. It would be disappointing if this research did not achieve that result.

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IQ as a necessary but not sufficient condition for genius

May 4, 2012

A quote from Arthur Jensen (From Steve Hsu. A fuller version of the interview can be found here): [T]he outstanding feature of any famous and accomplished person, especially a reputed genius, such as Feynman, is never their level of g (or their IQ), but some special talent and some other traits (e.g., zeal, persistence). Outstanding achievements(s) depend on these [...]

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Gandolfi, Gandolfi and Barash’s Economics as an Evolutionary Science

May 2, 2012

The fundamental insight that utility in economics should be based on the concept of fitness from evolutionary biology lies at the heart of Gandolfi, Gandolfi and Barash’s Economics as an Evolutionary Science: From Utility to Fitness. The first half of the book is fantastic, as the authors describe the economic way of thinking and Gary [...]

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Consilience conference afterthoughts

April 30, 2012

The Consilience Conference on evolution in biology, the social sciences and the humanities wrapped up on Saturday, and it was generally a high quality conference. It’s strength was that most of the presenters were doing work across multiple fields, usually with an evolutionary twist. Conferences such as these often involve people trying to frame existing [...]

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Group selection and the social sciences

April 27, 2012

The first day of the Consilience Conference has strengthened my feeling that support for group selection is growing in the social sciences. While the slant of speakers such as Edward O. Wilson and Herb Gintis is no surprise, the degree of support among many conference participants that I have spoken to was. The general argument [...]

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