Australian evolutionary biologist Rob Brooks’s book Sex, Genes & Rock ‘n’ Roll: How evolution has shaped the modern world has been released. It’s a good read – accessible and amusing. The books ranges between more serious issues such as obesity, population control and infanticide to the more light-hearted, the exploration of rock ‘n’ roll that the book title foreshadows. It is a book I’ll be adding to my list of recommendations for those who ask why evolution is relevant today.

I think it is fair to describe Brooks as an optimist when it comes to population. He shares the common view among biologists that resource scarcity and peak oil will be troublesome (an issue that I am relatively optimistic about – as most economists seem to be) but he finds hope that population growth may be curtailed. His logic lies in the idea of sexual conflict, which occurs because men and women do not have the same interests when it comes to mating. Women must invest in pregnancy, childbirth (which risks death) and breastfeeding, so have a higher incentive to invest in the child than the father, who only needs to give a couple of minutes of his services.

By considering sexual conflict, Brooks adds a dimension that is often missing from discussions of population. As power shifts in a relationship to the female, an expected result will be a reduction in fertility. If you wish to cut fertility, educate women and increase their power. However, I’m less optimistic than Brooks as I’m not convinced that the fertility decline will be permanent. and don’t consider increasing population to be a one way path to success in the long-term (despite the increase in ideas that comes with more people).

As I read the chapters that addressed sexual conflict, I realised that I should have written a few of my posts on Bryan Caplan’s Selfish Reasons to Have More Kids differently. Brooks alerted me to more dimensions of sexual conflict than I had considered at the time. In particular, the asymmetric investment of men and women makes statements that men and women want the same number of children seem even less plausible.

As a libertarian leaning economist, the chapter on obesity was the one that most directly confronted my biases. Brooks’s argument is that humans have evolved to varying degrees to the high carbohydrate diet of the modern world. As populations transition from their old diet high in protein, fat and complex carbohydrates, the risk of obesity increases. Populations with the shortest exposure to modern agriculture and grains are the most vulnerable. Once you add in the subsidies given to many grain and sugar producers and the higher prices of protein and fresh fruit and vegetables, this combination directs the human diet in the wrong direction.

The solution proposed by Brooks is to consider subsidising protein and vegetables, and taxing simple carbohydrates such as sugar. At the least, we should remove the perverse subsidies that we offer many farmers. Although I am always supportive of removing subsidies, I’m naturally wary of any story involving taxes or subsidies to shift human behaviour. However, I want to explore this issue in some depth, so will come back to it in a later post.

The rock ‘n’ roll story contained in the book is one that seems obvious, but at the same time, is a story that so many resist. Why are rock stars predominantly male? What is the evolutionary rationale for their actions when it seems to increase their death rate by so much? When you look at Brian Jones of the Rolling Stones, dead at 27 but with four children to four different mothers (and I’ve seen higher estimates of his reproductive output), the evolutionary explanation seems clear. Evolution is not just about survival – it is largely about sex. And if you want to read a book about sex, Brooks’s book is as fun to read as any.

In my previous two posts, I described the model contained in Galor and Moav’s paper Natural Selection and the Origin of Economic Growth and an extension in which we introduced genotypes with a low preference for educating their children.

Having been through the process of parametrising and simulating a complex economic model, I would recommend it as a method of increasing understanding of the basic model mechanics. More importantly, it can also highlight issues that are not clear from the mathematical consideration that is traditionally given to models.

When Nils-Petter Lagerlof simulated a similar model by Galor and Weil, he found that the population cycled between generations. If population was low, incomes would jump causing a population boom. In the next generation, that excess population would cause populations to crash. We found a similar result in Galor and Moav’s natural selection model. For the parameter values used in our paper, the population jumped or shrank by up to 30 per cent per generation. Many parameter values drove the population extinct. This made it difficult to use parameter values that generated realistic outcomes. The base level of investment per child used in the simulation is probably higher than I would have otherwise chosen, but low values made extinction more likely.

As Robert May discussed in his important 1976 paper, this reflects the fact that simple mathematical models can have very complicated dynamics. May showed that in a simple population model where population growth depends on the potential rate of population growth and the carrying capacity of the environment, the population trend can vary from a stable equilibrium to apparently chaotic population perturbations.

This observation is an important consideration with many economic models. Since simulating the Galor and Moav model, I have played with a few other economic models and have found that many have chaotic behaviour for certain parameter values and functional forms. I have been unable to simulate some models at all without the population crashing into extinction.

In my last post, I discussed Oded Galor and Omer Moav’s paper Natural Selection and the Origin of Economic Growth. As I noted then, my PhD supervisors, Juerg Weber and Boris Baer, and I have written a discussion paper that describes a simulation of the model.

In the discussion paper we discuss an extension of the model in which we consider the entry of people into the population that have a low preference for child quality – i.e. they weight child quantity more highly. Entry could be through migration or mutation. We show that if people with a low enough preference for quality enter the population, their higher fitness in the modern growth state can drive the economy back into Malthusian conditions.

To show this, we simulated a version of the model which had present at a low level in the initial population a genotype with a very low preference for educating their children (I refer to them as the strongly quantity-preferring genotype). This strongly quantity-preferring genotype has a similar fitness to other genotypes that do not educate in the Malthusian state, and declines in prevalence while the quality-preferring genotype increases.

Once the economy takes off into the modern growth state, the strongly quantity-preferring genotype has the highest fitness as it dedicates the lowest proportion of its resources to educating its children. The strongly quantity-preferring genotype increases in prevalence until, eventually, the average level of education plummets, undermining technological progress. The world returns to a Malthusian state, with high population growth eroding the income benefits of all earlier technological progress.

The following chart shows the rate of growth of population, technological progress and income per person. The first 70 to 80 generations look like the base model simulation I described in my earlier post. However, after that point, technological progress plummets to zero. For the next 150 or so generations, population growth is positive, which can occur as per person income is above subsistence. Eventually, population growth drives income down to subsistence levels.

In the next figure, you can see that the strongly quantity-preferring genotype, genotype c, grows from being a negligible part of the population to being over 90 per cent . It is this change in population composition that drives the return to Malthusian conditions (you can also see the small peak in quality-preferring types around generation 48 that kicks off the Industrial Revolution). The strongly quantity-preferring genotypes educate their children far less than the other genotypes, depressing technological progress.

There is no escape from the returned Malthusian conditions. The quality-preferring genotype will have a fitness advantage in this new Malthusian state and will increase in prevalence. Whereas that caused a take-off in economic growth the first time, this time there is no take-off. The strongly quantity-preferring types, which now dominate the population, cannot be induced to educate their children. They simply breed faster to take advantage of any technological progress spurred by the small part of the population that is educating their children.

This result could also be achieved by introducing the strongly quantity-preferring genotype into the simulation at other points in time. If it occurs after the Industrial Revolution, the timing of the return to Malthusian conditions will occur later. However, short of restricting the range of potential quality-quantity preferences, there is no way to avoid the return to Malthusian conditions in this version of model. The strongly quantity-preferring genotypes will always have a fitness advantage when income is above subsistence and their population growth will drive income back down to subsistence levels.

There are, of course, a few possible interpretations of this result. The model or assumptions may be missing an important element (or at the extreme are wrong). Humans may only have quality-quantity preferences in the growth promoting range. Or possibly, modern levels of economic growth are only transient.

Natural Selection and the Origin of Economic Growth by Oded Galor and Omer Moav is somewhat of an outlier. I’m not aware of any other paper that models the Industrial Revolution as a result of natural selection, apart from a similar paper by Galor and Michalopoulos. Zak and Park wrote a paper that examines population genetics and economic growth but they do not directly tackle the Industrial Revolution. In A Farewell to Alms, Greg Clark notes that Galor and Moav’s paper reignited his interest in this topic, but Clark does not model his hypothesis.

Galor and Moav’s paper is based on a model that has two types of people in the population. Each of these types has a genetically inherited preference for quality or quantity of children. The quality-preferring genotype wants their children to have higher human capital, so they invest more in their education, while the quantity-preferring genotype is more interested in raw numbers.

During the long Malthusian era in which both genotypes struggle to earn enough to subsist (i.e. during the thousands of years leading up the Industrial Revolution), the quality-preferring genotypes have a fitness advantage. As the quality-preferring genotypes are of higher quality, they earn higher wages. These higher wages are more than enough to cover education expenses, so they are also able to have more children than the quantity-preferring genotypes.

This fitness advantage leads the quality-preferring genotypes to increase in prevalence. As this occurs, technological progress increases, as the average level of education in the population drives technological progress. This in turn increases the incentive to invest in education, creating a feedback loop between technology and education.

As this goes on, the population grows. Per capita income does not increase as any technological progress is balanced out by population growth, which is the central problem of the Malthusian world.

Eventually, the rate of technological progress gets high enough to induce the quantity-preferring genotypes to invest in education. When this happens, the average level of education jumps, boosting technological progress and causing the Industrial Revolution.

During this process, the population growth rate changes. Up to the time of the Industrial Revolution, population growth increases with technological progress. However, when the level of technology leaps with the Industrial Revolution, the level of education becomes so high that population growth drops dramatically. Everyone is investing more into education than raw numbers of children.

From an evolutionary perspective, the Industrial Revolution also changes the selection pressure in the model. After the Industrial Revolution, the quality-preferring genotypes invest so much into education that they have lower fertility than the quantity-preferring genotypes. They then reduce in prevalence, their fitness advantage erased.

Galor and Moav paper work through the dynamics of the model using phase diagrams. It is not particularly easy or intuitive to see the processes working together in their paper, so my two PhD supervisors and I have just put out a discussion paper that describes simulations of the model – and shows the dynamics in a form that is easier to visually comprehend. In the chart below, you can see the dramatic jump in technological progress around generation 45 of the simulation, with per capita income growth also jumping at that time. Meanwhile, population growth drops to zero.

This second chart shows the change population composition. The quality-preferring genotype (genotype a) steadily increases in prevalence through to the Industrial Revolution, peaking at just under 5 per cent of the population. Afterwards, it is selected against.

This change in selection pressure has an interesting implication. While natural selection is the trigger of the Industrial Revolution, the population composition before and after the transition is the same. There is no difference in population composition between developed and undeveloped countries. The only time there is a difference in population composition is during the transition, when the quality-preferring genotypes peak.

In some ways, the natural selection occurring in Galor and Moav’s model is a sideshow to the main event, the quality-quantity trade-off. In a similar model by Galor and Weil, a scale effect triggered the Industrial Revolution – that is, the concept that more people leads to more ideas, so technological progress increases with population growth. I am sure that other triggers could be substituted.

That highlights the point where I am not convinced that the model is true (to the extent that a model can be). As far as human evolution relates to economic growth, I expect that inherent quality is more important (and by quality, I mean economically useful qualities) than the quality-quantity trade-off. The Industrial Revolution was possible because higher quality people were selected for in the lead-up (and the lead up encompasses thousands of years).

If quality is inherent, a high-quality person should have as many children as possible and this would have little effect on quality. For a man of low resources, his larger problem is convincing a woman to mate with him and not deciding on the right quantity-quantity mix.

The other thing that I should note is that, like most economic models, Galor and Moav’s model includes consumption with no clear evolutionary rationale (an issue I have discussed in an earlier post). Why do people in the model consume more than subsistence? If some people chose to focus all excess consumption into raising children they would come to dominate the population. This might be justified as being something to which the population has not yet adapted, but that explanation does not satisfy me.

Having made these quibbles, the model is still an impressive feat. It would not have been an easy task to create a model with technological progress, population and per capita income all following a path that resembles the last few thousand years of economic growth. There are some further issues and extensions to the model that we explore in the discussion paper I referred to above, but I’ll talk about them in my next post.

I was flipping through Chuck Palahniuk’s Fight Club last night, one of my favourite books. I hadn’t given much thought to this before, but I was wondering what motivated the space monkeys to join Project Mayhem. The novel hints that the space monkeys are a mix of lower status occupations. They are probably single and not actively participating in the mating market. So, to what extent would participation in Project Mayhem attract women?

I ask this question because the motivation that men have for status and success is largely due to the link with mating opportunities. When men undertake risky activities, the benefit is that higher status can translate into women. If it did not, risk taking tendencies would be selected against. Does Project Mayhem fit this picture?

Within Project Mayhem, the participants are all male. They do not understand the larger picture of Project Mayhem. Given that the rules state that you cannot talk about Project Mayhem, it must be difficult to use your involvement as a signal to women. The manner in which the space monkeys have specifically assigned tasks which they follow to the letter suggests that they may not be getting a large status boost within their new group.

Perhaps it is about self-improvement (although not in the sense that the book mocks). If you are at the lower end of the income scale and follow the consumerist trends, higher status men are likely to out-compete you. The book’s anti-consumerist thread, and the suggestion that we need external stimulus to stop us from treading water in our lives, might imply that the space monkeys joined to break from the inertia that traps them in a strategy certain to fail.

Or is participation resting on the outcome? Tyler Durden describes his vision:

You’ll hunt elk through the damp canyon forests around the ruins of Rockefeller Center, and dig clams next to the skeleton of the Space Needle leaning at a forty-five-degree angle. We’ll paint the skyscrapers with huge totem faces and goblin tikis, and every evening what’s left of mankind will retreat to empty zoos and lock itself in cages as protection against bears and big cats and wolves that pace and watch us from outside the cage bars at night.

….

“Imagine,” Tyler said, “stalking elk past department store windows and stinking racks of beautiful rotting dresses and tuxedos on hangers; you’ll wear leather clothes that will last you the rest of your life, and you’ll climb the wrist-thick kudzu vines that wrap the Sears Tower. Jack and the beanstalk, you’ll climb up through the dripping forest canopy and the air will be so clean you’ll see tiny figures pounding corn and laying strips of venison to dry in the empty car pool lane of an abandoned superhighway stretching eight-lanes-wide and August-hot for a thousand miles.”

In this new world, the relative status of the space monkeys, and their prospects for attracting women, might be quite different to that if they stayed in their low-status job.

Of course, I do not expect that women was what the author had in mind. As the narrator states, “I’m a thirty-year-old boy, and I’m wondering if another woman is really the answer I need.”

I have just started reading Geoffrey Miller’s Spent. It opens with a mildly amusing faux discussion in which a modern person seeks to convince some Cro-Magnons of the benefits of the modern way of life. The modern person is unable to do so as the discussion focuses on how the modern way of life does not increase the ability to attract and hold a mate (as opposed to, say, the rate of child mortality). In the conversation, it is noted that modern people work more, live marginally longer (compared to a Cro-Magnon that survives infancy) and have less connection to their community. Miller states:

This thought experiment has, I hope, shaken your faith that humanity has ridden a one-way escalator of ever-increasing progress and ever-greater happiness since the Aurignacian. True, modern life can be a wondrous glee-glutted Funky Town for the wealthiest .01 percent of people on the planet. However, a fairer assessment would contrast the lifeways of an average prehistoric human and the lifestyle of an average modern human.

The passage made me recall the choice facing Jemmy Button, one of the Fuegians collected by Captain FitzRoy in 1830 during the first voyage of the Beagle. After a year in England, Jemmy Button and the other two surviving Fuegians were taken on the second voyage of the Beagle to be returned home. On the Beagle for this voyage was Charles Darwin.

Darwin wrote that during his time in England, Jemmy Button had picked up many English habits:

Jemmy was short, thick, and fat, but vain of his personal appearance; he used always to wear gloves, his hair was neatly cut, and he was distressed if his well-polished shoes were dirtied. He was fond of admiring himself in a looking glass

When it came time to leave Jemmy Button in Tierra del Fuego, he was not pleased:

Poor Jemmy looked rather disconsolate, and would then, I have little doubt, have been glad to have returned with us. His own brother had stolen many things from him; and as he remarked, “What fashion call that:” he abused his countrymen, “all bad men, no sabe (know) nothing” and, though I never heard him swear before, “damned fools.” Our three Fuegians, though they had been only three years with civilised men, would, I am sure, have been glad to have retained their new habits; but this was obviously impossible.

Several months later, the Beagle returned to Jemmy Button’s area. Darwin writes:

This man was poor Jemmy, – now a thin, haggard savage, with long disordered hair, and naked, except a bit of blanket round his waist. We did not recognize him till he was close to us, for he was ashamed of himself, and turned his back to the ship. We had left him plump, fat, clean, and well-dressed; – I never saw so complete and grievous a change. As soon however as he was clothed, and the first flurry was over, things wore a good appearance. He dined with Captain Fitz Roy, and ate his dinner as tidily as formerly. He told us that he had “too much” (meaning enough) to eat, that he was not cold, that his relations were very good people, and that he did not wish to go back to England: in the evening we found out the cause of this great change in Jemmy’s feelings, in the arrival of his young and nice-looking wife.

In some ways, this hits Miller’s point – in his faux discussion, most of the discussion is about attracting mates and raising children. However, Jemmy Button’s situation is somewhat different. Jemmy Button would have been in a much worse position in England as his chance of attracting an English wife would have been near zero. There was a much stronger asymmetry in the potential of Jemmy Button’s options than if we were offered a straight decision between Cro-Magnon or modern existence.

Over the weekend I read Diane Coyle’s The Economics of Enough. I particularly enjoyed her dismantling of the concept that to increase happiness we should forget about growth. My reading list on this area has increased considerably – and it seems that I should place Amartya Sen high on that list. Coyle writes:

Those researchers like Richard Layard and Robert Frank who believe the link between growth and happiness tails off to nothing above a certain income level argue for taxes to make people stop working so hard or spend less on various consumer goods. The government must prod us into being happy because we’re simply adapting to each new level of income. The rat race means that like caged guinea pigs scrabbling around their wheel, we keep running to earn and spend more without making any progress in terms of happiness.

However, this kind of policy conclusion has been strongly challenged by other researchers. In his book The Idea of Justice Amartya Sen agrees that people’s happiness depends on their expectations, which are shaped by their own social situation. But he turns the argument about adaptation and the hedonic treadmill back on the happiness crowd: if we just aim for people to be happy with their lot, where is the social discontent that will create the momentum for a better life? Would women have ever gained the vote if many had not been unhappy? Would there have been a civil rights movement without discontent? Is poverty acceptable because poor people say they are pretty content? Obviously not; most people would agree the world with the discontent and change was better than the contented and static one.

As noted in my recent post on happiness adjusting, dissatisfaction might be a major driver of progress. However, there is a distinction between the policy concerns of Frank and Sen. Frank intends his taxes to cut competition in areas where the effort is wasteful and focused on relative status, such as competition for the largest house. Further, he intends progressive consumption taxes to allow reduction of taxes in other areas, such as those on income. That is a large step from taxing the poor because they will not be happier when richer.

Recently, I was asked whether the idea that I was espousing – considering human evolution in economics – was dangerous. For a perspective on debating dangerous ideas, it was suggested that it was worthwhile reading Steven Pinker’s introduction to the book What is Your Dangerous Idea? (HT Erik Postma).

Pinker argues both for and against treating some ideas as dangerous and possibly limiting their discussion. In addition to the usual arguments such as sunlight being the best disinfectant and that people will twist the debates to suit their own purposes, Pinker made some interesting observations.

One of them mirrors an argument that I use when people suggest that there are eugenic or Social Darwinistic implications to accepting that there is a genetic basis to human behaviour. Pinker notes that discrimination and oppression are deplorable, but that:

[N]one of them actually follows from the supposedly dangerous idea. Even if it turns out, for instance, that groups of people are different in their averages, the overlap is certainly so great that it would be irrational and unfair to discriminate against individuals on that basis. Likewise, even if it turns out that parents don’t have the power to shape their children’s personalities, it would be wrong on grounds of simple human decency to abuse or neglect one’s children.

The example I often use is IQ and education. If we accept that there is a genetic basis to IQ, this does not mean that we should shunt those who fall below a certain threshold up to the salt mines. Instead, schools can tailor their teaching to a range of capabilities and potentials.

The second point I found interesting related to who is making the argument. Pinker writes:

We must be especially suspicious when the danger in a dangerous idea is to someone other than its advocate.  Scientists, scholars, and writers are members of a privileged elite. They may have  an interest in promulgating ideas that justify their privileges, that blame or make light of society’s victims, or that earn them attention for cleverness and iconoclasm.

I expect that I am in the target audience for this point. I am a white, educated male in a developed country and am exploring how human evolution is relevant to economic questions such as the origin of economic growth. My research, if twisted in certain ways, could be argued to be justifying privilege. It could certainly be argued that I have an interest in earning attention for cleverness and iconoclasm.

So, how should I respond to this point? I like to think I am exploring these questions because I find them interesting and I don’t know all the answers. I want to understand them better. Perhaps it is signal that I should always bear in mind what my motivations are.

*As a footnote, I tried to buy an ebook copy of this book last night but the sellers blocked the purchase as I am in a territory in which it is not available. As is often the case, I found a free substitute. For those interested in reading the essays that formed the basis of the book, you can find them here (click on the contributors name for the essay). The essays range between the interesting and rehashes of old arguments that we’ve had for a very long time.

The post title is a bit tongue in cheek after I suffered a case of foot in mouth yesterday. I had the pleasure of presenting to some behavioural ecologists at the University of Zurich and was advocating for more “evolutionary biology imperialism” in economics. In the way that economists charge out of their field and seek to spread wisdom on everything, I want to see more evolutionary biologists doing the same and giving their perspectives on economics.

In the question session, we were discussing the heritability of fertility and which traits might influence this. In the back and forth, I stated (roughly) that if a woman in the 1970s adopted feminist beliefs, decided to focus on work and not have any children, her genes and any associated predispositions had now effectively exited the gene pool. While a wiser head might not have referred to feminism in the first place (it certainly didn’t help my case – it doesn’t matter what the particular beliefs are if they are heritable and affect fertility), I gave a brief justification on the grounds that political persuasion is heritable. In the aftermath, I thought I should re-read the article that I had in my mind – hence this post.

The article was by John Alford and colleagues and was published in the American Political Science Review. They analysed the heritability of political attitudes using the results of twin studies, and found that political attitudes had a genetic basis (heritability being the proportion of the variance in attitudes attributable to genetic variation). Attitudes are measured by a test that involves exposing the subject to a phrase with political connotations and asking for a response of agree, disagree or uncertain. Correlation between twins is then measured.

Alford and his colleagues found that the political attitudes of the identical twins were more similar than those of fraternal twins. Across the 28 political attitudes surveyed, the measured heritability ranged from 0.19 to 0.41, with an average of 0.32. Returning to my statement from yesterday, attitudes that might be (crudely) related to feminism include women’s liberation, with a heritability of 0.33, divorce (0.26) and abortion (0.25). The results are summarised in the following table.

Alford and colleagues then constructed an index of “conservatism” for each twin, with an agree or disagree to an issue giving a person a +1 or -1. Scores ranged from +26 to -26 (no-one was uniformly liberal or conservative across every item). For this index, the authors estimated heritability at 0.43, higher than for any individual item. This is not surprising as each issue is more subject to noise and idiosyncratic factors than overall political leanings. The heritability is even higher when the authors controlled for the correlation between parents (i.e. assuming people pair with people more like themselves), with the heritability estimate increasing to 0.53.

One interesting result was that political party affiliation has a lower level of heritability. The authors estimated it at 0.14, with shared and unshared environment the main factors that influence political affiliation. This suggests that parents and peers have a strong influence on which team someone joins, but less of an effect on what their position or overall leanings actually are.

To show that this was not just a United States phenomenon at a particular time, the authors compared the results to some Australian data. The results were similar. On my feminism slant, one of the Australian measures was attitudes to “working mothers”, which had a heritability of 0.27.

Alford and his colleagues closed with a note that heritability is a measure in a particular environment and that if the environment changes, so will the heritability. However, they note a number of implications of their findings for politics. First, they suggest that attitudes with a heritable basis will be more resistant to change. They will also be much harder to manipulate, whether by parents or political players. As evidence of this, the authors note that conservative politics from centuries ago reflects today’s conservative attitudes.

They also stated that a genetic basis to political attitudes means that we are likely to see broad but distinct political phenotypes. While they note that if one political leaning is more adaptive the people holding it should come to numerically dominate the other group, they prefer an explanation in which variation in political belief is adaptive.

For variation to be adaptive, this would require that a person’s fitness would (on average) increase as the prevalence of those who hold similar attitudes decreases. While that is a possibility, I am not sure what would be causing it, and as I wrote yesterday, there may be benefits to fitting in with a group. There is some evidence of positive selection for religiosity, but that would seem to be due to specific characteristics of the religion and not due to its prevalence.

Turning back to the issue I opened the post with, I would suggest that the political attitudes encapsulated under the banner “feminism” would have a heritable component. To the extent those beliefs lowered fertility, the genes associated with those traits would reduce in frequency. However, I am not aware of any empirical data on this. There is no shortage of people drawing the obvious implications in the literature, but has anyone actually done the numbers?

In all the debates about human biases, I like to believe that there is some benefit to being right. There must be some evolutionary benefit to knowing the true state of the world (on average). That is not to say that the benefits will always outweigh the costs, as the aim is to reproduce. Attracting a mate or surviving within a group may require holding some beliefs, such as religion. However, knowing that the snake will kill you will have fitness benefits.

Hitting on this subject, John Wilkins of Evolving Thoughts has a guest post up at Scientific American on the evolution of common sense. He puts the problem nicely:

With philosopher Paul Griffiths, I call this the Darwin’s Monkey Brain Problem: how can we rely upon a cognitive apparatus which had not evolved for finding out about the world, but instead for the purpose of getting primates laid?

Wilkins splits beliefs into moral, religious and environmental. On moral and religious beliefs, he states:

In the case of moral values, fitness is clearly at least in part down to our behaviour being acceptable to those around us, so that we do not suffer sanctions, and gain assistance when we need it. We are adapted to interpersonal and social interactions.

In the case of religious claims, as Griffiths and I argue, our beliefs are more likely to be fitness enhancing for much the same reasons as moral beliefs – they avoid our being censured, perhaps even executed as apostates or heretics, and increase our likelihood of receiving aid when we are in dire straits.

Beyond the benefits arising within a group, some religious or moral beliefs directly increase fitness. For example, a belief that contraception is not allowed may be fitness enhancing. Even activities that may be wasteful, such as participating in religious observances, might play a role as conspicuous leisure or consumption. The waste signals wealth or status to potential mates.

For environmental beliefs, Wilkins notes that there is generally direct feedback:

It seems likely that some beliefs – let us call them environmental beliefs – gain fitness because they track, if not exactly truth, then satisfactory ecological correlations. Obviously, if you believe there is a cliff in front of you, and there is, then you will tend not to leap over it, and your fitness is thereby enhanced. If you believe that rustling in the undergrowth is a leopard, and take evasive action, you are fitter than the poor thinker who takes a Plantingan line and treats it as a mere Kantian construct.

Some interesting questions arise when we come to debates about issues such as climate change. How are our minds shaped to deal with these questions and what are the fitness consequences of being right? Issues such as climate change seem to fall increasingly in the religious or moral categories. There are benefits of fitting in with a group. Truth seeking may not be the best fitness enhancing strategy. Further, it is hard to find any direct fitness consequences of being on either side of the climate debate. Our belief is unlikely to have fitness consequences, unless someone decides they have a particular interest in beach-side real estate.

I don’t find that very encouraging for my hope that there are benefits to being right (apart from personal smugness – although even that does not require that you are right, only that you believe you are right). I think the best bet is that, eventually, the consequences of climate change are so obvious that some people amend their beliefs to avoid signalling low intelligence. However, given how long people have held out in the evolution and creationism debates, this might be a rather long shot.