Levels of genetic diversity and economic prosperity (?)

Ewen Callaway tips me on the controversy surrounding a new paper which proposes a link between levels of genetic diversity and economic prosperity. I am linking to a version of the paper that is available online, as well as to a response by several geneticists, and a response to the response.

From the abstract, it seems that the authors are suggesting that there is an optimum level of genetic diversity, with either too little or too much of it being harmful for economic development.

Here are my own ideas on the general topic, prior to reading either the paper or the response letter.

Genetic diversity is, in general, a good thing for a population, for a simple reason: adaptation via natural selection depends on the existence of variation (there cannot be selection in the absence of alternatives). Other things being equal, a population possessing a greater amount of genetic diversity has a greater probability of already possessing adaptive alleles that might be necessary to meet new environmental challenges (e.g., pathogens).

But, we must also remember that genetic diversity can be partitioned to what is useful, neutral, or deleterious. We ought to be thankful that our Major Histocompatibility Complex (MHC) region is diverse, largely indifferent whether neutrally involving microsatellite loci have higher or lower allele variance in two populations, and a little concerned if there is an abundance of mildly deleterious rare variants sprinkled in our genomes, or a strong-effect disease-causing variant in one locus.

It is by no means clear whether human populations differ, and how they differ in each of these three components. Too much "neutral" diversity is patently irrelevant for economic prosperity; too much "useful" diversity may be helpful, and too much "deleterious" harmful, but I see no particular reason why populations would substantially differ in these two categories.

And, indeed, even the boundaries between the useful/neutral/deleterious categories are blurred. Deleterious anaemia-causing mutations are known to have benefits of malaria-resistance. Neutral variants may be "useful" ones in waiting: for example, lactase persistent mutants may have existed in the human species for hundreds of thousands of years, appearing and re-appearing by mutation, but it is when they encountered cow's milk and the need to drink it that they shifted from "neutral" to "useful". And, even useful alleles can cease to be so, e.g., the eradication of swamps and malaria in Greece has removed the benefit of malaria-resistence, and left only the harm of anaemia.

A different idea that one might consider is that diversity is sometimes harmful: for example, if you are picking a 4x100 relay team or hiring lumberjacks, or recruiting violinists, you don't especially want a genetically diverse group, but rather a restricted subset of phenotypes, and, inasmuch as phenotypes are influenced by genotypes, a restricted subset of genotypes as well: those with efficient fast twitch muscles, upper-body strength, and good pitch/finger dexterity respectively.

But, society is not a one-trick pony, and economies depend on an assortment of abilities. There is no "optimal human phenotype" that is good for all occupations, and most working societies have found ways to channel their diversity profitably, restricting it when necessary (e.g., picking a particular subset to be soccer players, and another subset to be figher pilots), or expanding it when necessary (e.g., assembling test groups that might mirror society, or the world at large).

Personally, I am sceptical of explanations that invoke long-standing evolutionary differences between populations. Such explanations (e.g., involving differences established during Out-of-Africa, as in this paper) have a hard time explaining "sign changes" in the direction of differences over the last few thousand years: China and Mesopotamia, were, by all accounts much more prosperous than most of Europe within historical memory, and the situation is now reversed -although it may be reversed yet again, if current trends continue, at least in the case of China. The people who erected massive monuments on the Americas do not appear to have been poorer than the Japanese of the time. Egypt used to be a breadbasket of Rome, but is now much poorer than Italy. In ancient times, Germans migrated to southern Europe, and during the 20th century many southern Europeans migrated into Germany.

If Out-of-Africa, 100 thousand years ago, sowed the seeds of differential economic prosperity, then these shifts in fortunes over the last few centuries or millennia are difficult to explain.

But, we also don't know that the pattern of genetic diversity observed in modern humans today is the result of Out-of-Africa. Evidence has been slowly and steadily accumulating, that people who live in different parts of the world today are not necessarily the same people of the ones who lived there a few thousand years ago. Migration and admixture have changed the landscape of human genetic variation: migration by expanding "narrow" genetic pools into much wider territories, and admixture by increasing diversity in contact zones.

So, to summarize:

1. Genetic diversity can be positive, neutral, or deleterious; boundaries between these categories are fluid, and their apportionment in different populations is uncertain.
2. Current differences in economic development are in contrast with such differences in the recent historical past, weakening the case that they stem from events that took place in the distant past (such as Out-of-Africa)
3. Current population differences in genetic diversity may have been established by migration and admixture in the recent past, rather than reflecting on events that took place in the distant past.

So, I am rather unconvinced of the hypothesis advanced by Ashraf and Galor. If I find something to add after reading their paper, I will add it here as an update.

RePEc:bro:econwp:2010-7

The "Out of Africa" Hypothesis, Human Genetic Diversity, and Comparative Economic Development

Quamrul Ashraf, Oded Galor

This research argues that deep-rooted factors, determined tens of thousands of years ago, had a significant effect on the course of economic development from the dawn of human civilization to the contemporary era. It advances and empirically establishes the hypothesis that in the course of the exodus of Homo sapiens out of Africa, variation in migratory distance from the cradle of humankind to various settlements across the globe affected genetic diversity and has had a direct long-lasting effect on the pattern of comparative economic development that could not be captured by contemporary geographical, institutional, and cultural factors. In particular, the level of genetic diversity within a society is found to have a hump-shaped effect on development outcomes in the pre-colonial era, reflecting the trade-off between the beneficial and the detrimental effects of diversity on productivity. Moreover, the level of genetic diversity in each country today (i.e., genetic diversity and genetic distance among and between its ancestral populations) has a similar non-monotonic effect on the contemporary levels of income per capita. While the intermediate level of genetic diversity prevalent among the Asian and European populations has been conducive for development, the high degree of diversity among African populations and the low degree of diversity among Native American populations have been a detrimental force in the development of these regions. Further, the optimal level of diversity has increased in the process of industrialization, as the beneficial forces associated with greater diversity have intensified in an environment characterized by more rapid technological progress.

Link

Response to Ashraf and Galor 'The Out of Africa Hypothesis, Human Genetic Diversity and Comparative Economic Development'

Jade D'Alpoim Guedes et al.

Abstract:

This short reply summarizes the concerns of the anthropological community about Ashraf and Galor's (Forthcoming) article in the American Economic Review.

Link

Response to Comments made in a Letter by Guedes et al. on “The Out of Africa Hypothesis, Human Genetic Diversity and Comparative Development”

Link (pdf)

Mapping Stereotypes

If you're in need of a good belly laugh, I'm sure you'll find something in the Mapping Stereotypes site to suit you.

Geographic orientation and cultural homogeneity

Excellent coverage of this article at Nature News:

The researchers found that if a country had a greater east–west axis than a north–south one, the less likely it was for its indigenous languages to persist. The relationship isn't straightforward, but the model suggests that Mongolia, which is about twice as wide as it is tall, would have 5% fewer indigenous languages than Angola, which is roughly square. Meanwhile, Peru — about twice as tall as it is wide — would be predicted to have 5% more persistent languages than Angola. The result, say the authors, supports Diamond's theory because it indicates that east–west countries have more homogeneous cultures.

PNAS doi: 10.1073/pnas.1205338109

Geographic axes and the persistence of cultural diversity

David D. Laitin et al.

Jared Diamond’s Guns, Germs, and Steel [Diamond J, (1997) Guns, Germs, and Steel (WW Norton, NY)] has provided a scientific foundation for answering basic questions, such as why Eurasians colonized the global South and not the other way around, and why there is so much variance in economic development across the globe. Diamond’s explanatory variables are: (i) the susceptibility of local wild plants to be developed for self-sufficient agriculture; (ii) the domesticability of large wild animals for food, transport, and agricultural production; and (iii) the relative lengths of the axes of continents with implications for the spread of human populations and technologies. This third “continental axis” thesis is the most difficult of Diamond’s several explanatory factors to test, given that the number of continents are too few for statistical analysis. This article provides a test of one observable implication of this thesis, namely that linguistic diversity should be more persistent to the degree that a geographic area is oriented more north-south than east-west. Using both modern states and artificial geographic entities as the units of analysis, the results provide significant confirmation of the relationship between geographic orientation and cultural homogenization. Beyond providing empirical support for one observable implication of the continental axis theory, these results have important implications for understanding the roots of cultural diversity, which is an important determinant of economic growth, public goods provision, local violence, and social trust.

Link

Tight/loose culture influenced by a nation's past

Audio interview with lead author in NPR, also has a table with 10 loosest and 10 tightest cultures (left).

Another podcast in Science.

From the press release:

Gelfand and colleagues found that countries such as Japan, Korea, Singapore and Pakistan are much tighter whereas countries such as the Ukraine, Israel, Brazil, and the U.S. are looser. Their research further showed that a nation's tightness or looseness is in part determined by the ecological and human factors that have shaped its history – including wars, natural disasters, disease outbreaks, population density and scarcity of natural resources. Tight and loose societies also vary in their institutions—with tight societies having more autocratic governments, more closed media, and criminal justice systems that had more monitoring and greater deterrence of crime as compared to loose societies.

The study found that the situations that people encounter differ in tight and loose societies. For example, everyday situations—like being in park, a classroom, the movies, a bus, at job interviews, restaurants, and even one's bedroom—constrain behavior much more in tight societies and afford a wider range of behavior in loose societies.

"We also found that the psychological makeup of individual citizens varies in tight and loose societies," Gelfand said. "For example, individuals in tight societies are more prevention focused (attentive to rules), have higher self-regulation strength (more impulse control) and have higher needs for order and self-monitoring abilities than individuals in loose societies. These attributes, Gelfand said, help people to adapt to the level of constraint (or latitude) in their cultural context, and at the same time, reinforce it.

Science 27 May 2011:
Vol. 332 no. 6033 pp. 1100-1104
DOI: 10.1126/science.1197754

Differences Between Tight and Loose Cultures: A 33-Nation Study

Michele Gelfand et al.

With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change.

Link

Medieval GDP per capita

On the left there are some interesting tables from the paper.

I don't know how accurate of GDP per capita is that far in the past, as a certain number of assumptions must come into play. However, these numbers should give pause to anyone who makes broad statements about different populations' innate ability based on their present- or recent economic output, especially when such inferences are pushed thousands of years into the past.

The paper also has some estimates of population and population growth rates which should be interesting for population geneticists in calibrating their models.

Medieval England Twice as Well Off as Today’s Poorest Nations

New research led by economists at the University of Warwick reveals that medieval England was not only far more prosperous than previously believed, it also actually boasted an average income that would be more than double the average per capita income of the world's poorest nations today.

The WEIRDest people in the world

There is a freely available version of this article here (pdf).

Behav Brain Sci. 2010 Jun;33(2-3):61-83. Epub 2010 Jun 15.

The weirdest people in the world?

Henrich J, Heine SJ, Norenzayan A.

Abstract

Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers - often implicitly - assume that either there is little variation across human populations, or that these "standard subjects" are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species - frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior - hence, there are no obvious a priori grounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions of human nature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges.

Link

Parasites and Intelligence (Eppig et al. 2010)

This is as good an explanation for global differences in IQ as I have ever seen. It proposes that IQ differences between human groups are created during ontogeny due to an energetic trade-off between brain development and immune response to infectious disease. In regions of the world with a high parasite burden, there is an elevated amount of energy used up to fight disease, at the expense of brain development.

Notice that this is not an explanation requiring genetic adaptation. Parasite burden inhibits cognitive function development. Indeed, if one were to make an adaptive argument (and I will not!), it would be in the direction of greater brain development genetic potential in parasite-heavy locales to counteract the effects of disease, i.e., the selection of individuals that may withstand the rigors of fighting off infectious disease without compromising cognitive function.

The authors write:

Multiple regression shows that, of infectious disease, temperature, evolutionary novelty and AVED, infectious disease is the best predictor of intelligence by a large margin.

...

If the general pathway we propose is correct, there are two plausible mechanisms by which a trade-off in allocation of energy to immune function versus brain development and maintenance may occur. First, parasitic infection may intermittently cause the redirection of energy away from brain development. In this case, during periods of infection, the brain receives fewer energetic resources, but this allocation to brain function will return to pre-infection levels during healthy periods. During periods of infection, whatever aspects of the brain that are growing and developing will suffer reduced phenotypic quality. Second, exposure to infectious agents may cause a developmental pathway that permanently invests more energy into immune function at the expense of brain growth. In this scenario, large amounts of energy would be allocated into immune function during periods of health, as opposed to only redirecting energy during periods of infection. This could operate through a variety of mechanisms. A plausible mechanism is that higher investment in immune system is triggered by individual exposure to infectious disease at some point during ontogeny. This may include triggering from exposure to maternal antibodies while in utero.

...

Our findings suggest that the heritable variation in intelligence may come from two sources: brain structure and immune system quality. Thus, two individuals may possess identical genes for brain structure, but have different IQ owing to differences in immune system quality reflecting their personal allocation of energy into brain development versus immunity.

...

Our findings are consistent with a number of other findings in the literature. In particular, the Flynn effect (Flynn 1987) demands that any hypothesis regarding the worldwide variation and distribution of intelligence must be able to account for some factor that allows for large IQ gains over time spans seemingly too short to be attributed to evolution by natural selection. The parasite-stress hypothesis allows for such a factor in the form of reduced parasitic infection. As societies become modernized, decreased parasite stress may occur through multiple pathways. As national wealth increases, medicine, vaccinations and potable water can be purchased by both the government and by individuals. Moreover, there is cross-national evidence that, as democratization increases, there are corresponding increases in public health legislation and infrastructure. Democratization also increases levels of education, better allowing individuals to seek out and understand information that reduces parasitic infection (Thornhill et al. 2009). This source of endogeneity is not a flaw, but a prediction of our hypothesis.

Related:

• Pathogens and Collectivism
• Religious Diversity and pathogens

Proceedings of the Royal Society B doi:10.1098/rspb.2010.0973

Parasite prevalence and the worldwide distribution of cognitive ability

Christopher Eppig et al.

Abstract

In this study, we hypothesize that the worldwide distribution of cognitive ability is determined in part by variation in the intensity of infectious diseases. From an energetics standpoint, a developing human will have difficulty building a brain and fighting off infectious diseases at the same time, as both are very metabolically costly tasks. Using three measures of average national intelligence quotient (IQ), we found that the zero-order correlation between average IQ and parasite stress ranges from r = −0.76 to r = −0.82 (p less than 0.0001). These correlations are robust worldwide, as well as within five of six world regions. Infectious disease remains the most powerful predictor of average national IQ when temperature, distance from Africa, gross domestic product per capita and several measures of education are controlled for. These findings suggest that the Flynn effect may be caused in part by the decrease in the intensity of infectious diseases as nations develop.

Link

Wealth and people and the invasion of alien species

This is an open access paper.

PNAS doi:10.1073/pnas.1002314107

Disentangling the role of environmental and human pressures on biological invasions across Europe

Petr Pyšek et al.

The accelerating rates of international trade, travel, and transport in the latter half of the twentieth century have led to the progressive mixing of biota from across the world and the number of species introduced to new regions continues to increase. The importance of biogeographic, climatic, economic, and demographic factors as drivers of this trend is increasingly being realized but as yet there is no consensus regarding their relative importance. Whereas little may be done to mitigate the effects of geography and climate on invasions, a wider range of options may exist to moderate the impacts of economic and demographic drivers. Here we use the most recent data available from Europe to partition between macroecological, economic, and demographic variables the variation in alien species richness of bryophytes, fungi, vascular plants, terrestrial insects, aquatic invertebrates, fish, amphibians, reptiles, birds, and mammals. Only national wealth and human population density were statistically significant predictors in the majority of models when analyzed jointly with climate, geography, and land cover. The economic and demographic variables reflect the intensity of human activities and integrate the effect of factors that directly determine the outcome of invasion such as propagule pressure, pathways of introduction, eutrophication, and the intensity of anthropogenic disturbance. The strong influence of economic and demographic variables on the levels of invasion by alien species demonstrates that future solutions to the problem of biological invasions at a national scale lie in mitigating the negative environmental consequences of human activities that generate wealth and by promoting more sustainable population growth.

Link

Soil and climate as economic destiny

Figure 1 (on the left) Modelled “suitability” (probability of occurrence, Maxent) for (A) agriculture, (B) sedentary animal husbandry, (C) nomadic pastoralism, and (D) hunting and gathering.

From the paper:

Our simplistic exercise showed that a “geo-deterministic” approach can predict surprisingly many features of human cultural geography without any explicit cultural or historical assumptions. Although many deviations require further factors for a satisfying explanation, the nature of these deviations invite the generation of hypotheses for further research. Our ‘null model’ offers a highly parsimonious, empirically supported explanation to the question of why some regions are more “powerful” than others, supplementing the idea of a historical effect operating through the timing of transition to agriculture [2].

In some instances, our model may actually provide a simpler explanation. Putterman [10], for example, suggested that the dominance of Western European cultures indicates the transmission of “civilization” traits (other than knowledge on agriculture) from regions of first domestication. Our data indicate that higher climatic suitability may have been sufficient for Europe to “catch up”, allowing for much higher population densities than, e.g., the “fertile crescent” region. Models of “suitability” under past climatic scenarios may be helpful to evaluate this. Similarly, models applied to predicted future climatic scenarios may be useful to anticipate changes of the economic suitability of landuse types.

However, our model has clear deviations in some regions that may well be explicable by the availability of animals and plants suitable for domestication (e.g., central Africa). Apart from that, and more importantly, we know that human societies and economies went through historical development, so ignoring history may not always be the best strategy to understand causalities. This problem occurs also with other research questions in biogeography, e.g. when investigating global biodiversity patterns [45]–[47]. Nevertheless, our ‘null model’ will be a useful tool in identifying regions that require further investigation to understand additional processes that shape the distribution and performance of human economic traits.

I really like this type of paper that looks at a simple explanation for a phenomenon, in this case, economic output as a product of soil/climate quality and suitability. As the authors point out, their "null" model has its limitations, and it is precisely in regions of the world where its predictions do not match the observations, that we should look for additional factors (besides soil and climate) to explain economic traits.

Related: Soil and Greek temples.

PLoS ONE 5(5): e10416. doi:10.1371/journal.pone.0010416

Is the Spatial Distribution of Mankind's Most Basic Economic Traits Determined by Climate and Soil Alone?

Jan Beck, Andrea Sieber

Abstract

Background
Several authors, most prominently Jared Diamond (1997, Guns, Germs and Steel), have investigated biogeographic determinants of human history and civilization. The timing of the transition to an agricultural lifestyle, associated with steep population growth and consequent societal change, has been suggested to be affected by the availability of suitable organisms for domestication. These factors were shown to quantitatively explain some of the current global inequalities of economy and political power. Here, we advance this approach one step further by looking at climate and soil as sole determining factors.

Methodology/Principal Findings
As a simplistic ‘null model’, we assume that only climate and soil conditions affect the suitability of four basic landuse types – agriculture, sedentary animal husbandry, nomadic pastoralism and hunting-and-gathering. Using ecological niche modelling (ENM), we derive spatial predictions of the suitability for these four landuse traits and apply these to the Old World and Australia. We explore two aspects of the properties of these predictions, conflict potential and population density. In a calculation of overlap of landuse suitability, we map regions of potential conflict between landuse types. Results are congruent with a number of real, present or historical, regions of conflict between ethnic groups associated with different landuse traditions. Furthermore, we found that our model of agricultural suitability explains a considerable portion of population density variability. We mapped residuals from this correlation, finding geographically highly structured deviations that invite further investigation. We also found that ENM of agricultural suitability correlates with a metric of local wealth generation (Gross Domestic Product, Purchasing Power Parity).

Conclusions/Significance
From simplified assumptions on the links between climate, soil and landuse we are able to provide good predictions on complex features of human geography. The spatial distribution of deviations from ENM predictions identifies those regions requiring further investigation of potential explanations. Our findings and methodological approaches may be of applied interest, e.g., in the context of climate change.

Link

Preference for masculine/feminine-looking men and national health

Supplementary Table 1 has the relevant data. I have sorted the data on national health index, and average masculinity preference.



Note that country scores were limited only to those judges who identified themselves as White.

Some observations:

• As the authors note health index is related inversely with preference for masculinity. However, there are some interesting cases:
• Canada and the USA have similar (high) masculinity preferences, even though they differ substantially in the health index.
• Iceland and Norway (small sample sizes, but we can combine the two) have a good health index as does Sweden, but a much stronger preference than masculinity than Sweden.
• The vast majority of EU nations are around ~0.4 in the masculinity preference index.

An untested factor is variation in the levels of facial masculinity across different nations. Differences in preference may not reflect differences in health, but rather differences in average facially-expressed masculinity. It would be interesting to use anthropometric data to test this possible influence, as "White" populations from different nations are not anthropometrically equivalent.

Another untested factor is the racial makeup of different nations. It is fairly striking that the top nations in masculinity preference (we can exclude Bulgaria with its small sample) are all the ones with the longest histories of racial co-existence. This may have altered attractiveness standards in these countries, as the Caucasoids within each country may have altered perceptions of attractiveness due either to familiarization with other races or (conversely) due to a desire to distance themselves from them phenotypically.

PS: You can download the paper and other face-related research at the Facelab.

Proceedings of the Royal Society B doi:10.1098/rspb.2009.2184

The health of a nation predicts their mate preferences: cross-cultural variation in women's preferences for masculinized male faces

Lisa M. DeBruine et al.

Abstract

Recent formulations of sexual selection theory emphasize how mate choice can be affected by environmental factors, such as predation risk and resource quality. Women vary greatly in the extent to which they prefer male masculinity and this variation is hypothesized to reflect differences in how women resolve the trade-off between the costs (e.g. low investment) and benefits (e.g. healthy offspring) associated with choosing a masculine partner. A strong prediction of this trade-off theory is that women's masculinity preferences will be stronger in cultures where poor health is particularly harmful to survival. We investigated the relationship between women's preferences for male facial masculinity and a health index derived from World Health Organization statistics for mortality rates, life expectancies and the impact of communicable disease. Across 30 countries, masculinity preference increased as health decreased. This relationship was independent of cross-cultural differences in wealth or women's mating strategies. These findings show non-arbitrary cross-cultural differences in facial attractiveness judgements and demonstrate the use of trade-off theory for investigating cross-cultural variation in women's mate preferences.

Link

Coevolution of individualism–collectivism and the serotonin transporter gene

From the paper:

Here, we demonstrate for the first time a robust association between cultural values of individualism–collectivism and allelic frequency of the serotonin transporter gene, controlling for associated economic and disease factors. Geographical regions characterized by cultural collectivism exhibit a greater prevalence of S allele carriers of the serotonin transporter gene, even when cultural regions rather than nations served as the unit of analysis. Additionally, we show that global variability in historical pathogen prevalence predicts global variability in individualism–collectivism owing to genetic selection of the S allele of the serotonin transporter gene in regions characterized by high collectivism. Importantly, we also reveal a novel and surprising negative association between individualism–collectivism, frequency of S allele carriers of the serotonin transporter gene and global prevalence of anxiety and mood disorder. Across nations, both collectivism and allelic frequency of the S allele negatively predict global prevalence of anxiety and mood disorders. Critically, our results further indicate that greater population frequency of S allele carriers is associated with decreased prevalence of anxiety and mood disorders due to increased cultural collectivism.

The current findings suggest a novel demonstration of culture–gene coevolution of human behaviour. Emphasizing social norms that increase social harmony and encourage giving social support to others, collectivism serves an ‘anti-psychopathology’ function by creating an ecological niche that lowers the prevalence of chronic life stress, protecting genetically susceptible individuals from environmental pathogens known to trigger negative emotion and psychopathology. These findings complement notions that cultural values of individualism and collectivism are adaptive and by-products of evolution, more broadly. For instance, recent evidence suggests that cultural values of collectivism also serve an ‘anti-pathogen defence’ whereby behavioural manifestations of collectivism, such as conformity and parochialism, function as buffers against the transmission and increased prevalence of disease-causing pathogens (e.g. malaria, typhus and tuberculosis) (Fincher et al. 2008). Our results provide novel evidence that geographical regions characterized by collectivistic cultural norms have a higher historical and contemporary prevalence of infectious diseases due, at least partially, to genetic selection of S allele carriers (Fincher et al. 2008). Taken together, these findings dovetail nicely as two examples of how cultural values serve adaptive functions by tuning societal behaviour so that social and environmental risk factors are reduced and physical and mental health of group members is maintained. Importantly, in the current study, we found that population frequency of the serotonin transporter gene was a singular predictor of cultural values of individualism–collectivism across nations, even when controlling for historical and contemporary pathogen prevalence. Hence, our findings illustrate that gene frequency plays a unique role in explaining global variation in the adoption of cultural norms and is fundamental to any comprehensive understanding of culture.

Proceedings of the Royal Society B doi:10.1098/rspb.2009.1650

Culture–gene coevolution of individualism–collectivism and the serotonin transporter gene


Joan Y. Chiao, and Katherine D. Blizinsky

Culture–gene coevolutionary theory posits that cultural values have evolved, are adaptive and influence the social and physical environments under which genetic selection operates. Here, we examined the association between cultural values of individualism–collectivism and allelic frequency of the serotonin transporter functional polymorphism (5-HTTLPR) as well as the role this culture–gene association may play in explaining global variability in prevalence of pathogens and affective disorders. We found evidence that collectivistic cultures were significantly more likely to comprise individuals carrying the short (S) allele of the 5-HTTLPR across 29 nations. Results further show that historical pathogen prevalence predicts cultural variability in individualism–collectivism owing to genetic selection of the S allele. Additionally, cultural values and frequency of S allele carriers negatively predict global prevalence of anxiety and mood disorder. Finally, mediation analyses further indicate that increased frequency of S allele carriers predicted decreased anxiety and mood disorder prevalence owing to increased collectivistic cultural values. Taken together, our findings suggest culture–gene coevolution between allelic frequency of 5-HTTLPR and cultural values of individualism–collectivism and support the notion that cultural values buffer genetically susceptible populations from increased prevalence of affective disorders. Implications of the current findings for understanding culture–gene coevolution of human brain and behaviour as well as how this coevolutionary process may contribute to global variation in pathogen prevalence and epidemiology of affective disorders, such as anxiety and depression, are discussed.

Link

DNA tests for asylum seekers

ScienceInsider has some reactions to plans from the UK Border Agency to use DNA tests to verify claims of asylum seekers that they do in fact come from the countries they claim (e.g., Somalia), rather than other ones which do not face the same geopolitical turmoil. This is a real problem for European countries, as many illegal immigrants without documents claim to be from war-zones.

I am completely in agreement with the use of DNA tests to substantiate asylum seekers' claims, with the caveat that the followed protocols should be transparent to the scientific community, so that they can be subjected to scrutiny. Right now, many DNA testing companies make bold assertions of being able to distinguish one ethnicity from another, but given that their methods are "closed box", their results are suspect.

However, it is completely inaccurate that DNA is unrelated to ethnicity. Both simple uniparental tests (Y chromosome and mtDNA), and of course autosomal panels, are useful in updating (via Bayes' rule) one's prior belief in a particular hypothesis.

A combination of linguistic assessment (whether someone knows the language of the country he claims to be form), tests of common knowledge (whether someone knows some simple facts about that country), and a DNA test (whether someone has DNA that is common in this country) is enough to determine whether someone is from some claimed origin.

Such determinations are never foolproof, but there really is no foolproof method of determining that a person with no papers is in fact what he says he is. However, they can, in fact, both statistically confirm or reject a great number of cases with very high probability of being right. This, in itself, is a great improvement.

Macedonia Evidence initiative

A very worthwhile effort. From the About section of the website:

Classical Scholars from around the world, well known for their expertise in the history of Greece are presenting, examining, and discussing the historical evidence.

The first few scholars were motivated by the article in the Archaeology magazine, and the letter Stephen G. Miller, Ph.D sent in response, which Archaeology did not publish.

Since then, the list of scholars that have examined the evidence has been growing and 222 scholars have undersigned the letter to President Barak Obama.

If you want to contribute to the discussion, please contact us at: SavingAlexander@macedonia-evidence.org.

The text of the letter:

Dear President Obama,

We, the undersigned scholars of Graeco-Roman antiquity, respectfully request that you intervene to clean up some of the historical debris left in southeast Europe by the previous U.S. administration.

On November 4, 2004, two days after the re-election of President George W. Bush, his administration unilaterally recognized the “Republic of Macedonia.” This action not only abrogated geographic and historic fact, but it also has unleashed a dangerous epidemic of historical revisionism, of which the most obvious symptom is the misappropriation by the government in Skopje of the most famous of Macedonians, Alexander the Great.

We believe that this silliness has gone too far, and that the U.S.A. has no business in supporting the subversion of history. Let us review facts. (The documentation for these facts [here in boldface] can be found attached and at: http://macedonia-evidence.org/documentation.html)

The land in question, with its modern capital at Skopje, was called Paionia in antiquity. Mts. Barnous and Orbelos (which form today the northern limits of Greece) provide a natural barrier that separated, and separates, Macedonia from its northern neighbor. The only real connection is along the Axios/Vardar River and even this valley “does not form a line of communication because it is divided by gorges.”

While it is true that the Paionians were subdued by Philip II, father of Alexander, in 358 B.C. they were not Macedonians and did not live in Macedonia. Likewise, for example, the Egyptians, who were subdued by Alexander, may have been ruled by Macedonians, including the famous Cleopatra, but they were never Macedonians themselves, and Egypt was never called Macedonia.

Rather, Macedonia and Macedonian Greeks have been located for at least 2,500 years just where the modern Greek province of Macedonia is. Exactly this same relationship is true for Attica and Athenian Greeks, Argos and Argive Greeks, Corinth and Corinthian Greeks, etc.

We do not understand how the modern inhabitants of ancient Paionia, who speak Slavic – a language introduced into the Balkans about a millennium after the death of Alexander – can claim him as their national hero. Alexander the Great was thoroughly and indisputably Greek. His great-great-great grandfather, Alexander I, competed in the Olympic Games where participation was limited to Greeks.

Even before Alexander I, the Macedonians traced their ancestry to Argos, and many of their kings used the head of Herakles - the quintessential Greek hero - on their coins.

Euripides – who died and was buried in Macedonia– wrote his play Archelaos in honor of the great-uncle of Alexander, and in Greek. While in Macedonia, Euripides also wrote the Bacchai, again in Greek. Presumably the Macedonian audience could understand what he wrote and what they heard.

Alexander’s father, Philip, won several equestrian victories at Olympia and Delphi, the two most Hellenic of all the sanctuaries in ancient Greece where non-Greeks were not allowed to compete. Even more significantly, Philip was appointed to conduct the Pythian Games at Delphi in 346 B.C. In other words, Alexander the Great’s father and his ancestors were thoroughly Greek. Greek was the language used by Demosthenes and his delegation from Athens when they paid visits to Philip, also in 346 B.C. Another northern Greek, Aristotle, went off to study for nearly 20 years in the Academy of Plato. Aristotle subsequently returned to Macedonia and became the tutor of Alexander III. They used Greek in their classroom which can still be seen near Naoussa in Macedonia.

Alexander carried with him throughout his conquests Aristotle’s edition of Homer’s Iliad. Alexander also spread Greek language and culture throughout his empire, founding cities and establishing centers of learning. Hence inscriptions concerning such typical Greek institutions as the gymnasium are found as far away as Afghanistan. They are all written in Greek.

The questions follow: Why was Greek the lingua franca all over Alexander’s empire if he was a “Macedonian”? Why was the New Testament, for example, written in Greek?

The answers are clear: Alexander the Great was Greek, not Slavic, and Slavs and their language were nowhere near Alexander or his homeland until 1000 years later. This brings us back to the geographic area known in antiquity as Paionia. Why would the people who live there now call themselves Macedonians and their land Macedonia? Why would they abduct a completely Greek figure and make him their national hero?

The ancient Paionians may or may not have been Greek, but they certainly became Greekish, and they were never Slavs. They were also not Macedonians. Ancient Paionia was a part of the Macedonian Empire. So were Ionia and Syria and Palestine and Egypt and Mesopotamia and Babylonia and Bactria and many more. They may thus have become “Macedonian” temporarily, but none was ever “Macedonia”. The theft of Philip and Alexander by a land that was never Macedonia cannot be justified.

The traditions of ancient Paionia could be adopted by the current residents of that geographical area with considerable justification. But the extension of the geographic term “Macedonia” to cover southern Yugoslavia cannot. Even in the late 19th century, this misuse implied unhealthy territorial aspirations.

The same motivation is to be seen in school maps that show the pseudo-greater Macedonia, stretching from Skopje to Mt. Olympus and labeled in Slavic. The same map and its claims are in calendars, bumper stickers, bank notes, etc., that have been circulating in the new state ever since it declared its independence from Yugoslavia in 1991. Why would a poor land-locked new state attempt such historical nonsense? Why would it brazenly mock and provoke its neighbor?

However one might like to characterize such behavior, it is clearly not a force for historical accuracy, nor for stability in the Balkans. It is sad that the United States of America has abetted and encouraged such behavior.

We call upon you, Mr. President, to help - in whatever ways you deem appropriate - the government in Skopje to understand that it cannot build a national identity at the expense of historic truth. Our common international society cannot survive when history is ignored, much less when history is fabricated.

The Frequently Asked Questions are worth reading too.

European School Survey on Alcohol and Other Drugs

The ESPAD 2007 report (pdf) has been released, and has received coverage from various countries (e.g., UK UK Ireland Malta Slovenia Czech Republic). Here is a summary of the results for Greece. The lower than average cigarette consumption, coupled with an apparently decreasing trend may be a hopeful sign for younger generations of Greeks.

Greece is one of the countries that reported rather moderate alcohol, tobacco and other drug habits.
However, the proportion of students who had been drinking alcohol during the past 12 months (87%) is somewhat higher than the ESPAD average. Being drunk, on the other hand, is not as common in Greece as in many other ESPAD countries: one fourth (26%) of the students reported this. Estimated consumption on the latest drinking day (3.1 cl alc. 100%) was also lower than average. About one-fifth (22%) of the Greek participants had been smoking during the past 30 days, which is lower than average. The lifetime prevalence of cannabis use (6%) is also low, at about one third of the ESPAD mean. Use of drugs other than cannabis (5%), on the other hand, is close to average. Rather small proportions of students report other behaviours such as lifetime use of inhalants (9%), non-prescription use of tranquillisers or sedatives (4%) and combined use of alcohol and pills (3%).

Slavopaionian propaganda video + Stephen Miller's excellent letter to Archaeology magazine

Last year, when the "Macedonian issue" was in the news, due to FYROM's NATO candidacy I proposed that the issue could be resolved if FYROM accepted a compromise in the "name issue" that would qualify "Macedonia" with an appropriate geographical disambiguating adjective.

Events since that time have further strengthened my belief that no compromise is possible any more with our neighbors to the north, who refuse to budge even to the slightest degree in their stubborn adherence to their invented identity.

If you are in doubt of the degree of irrationality present in FYROM, this official video in state TV will change your mind:



The part at 04:25 is especially strange, where the narrator announces that one of the three races of mankind are the "Whites-Macedonoids" who spread to the "Sea of Japan", but the whole thing has a lunatic vibe to it.

On a more positive note, Prof. Stephen G. Miller's letter to Archaeology magazine is a welcome scholarly demolition of the Slavomacedonians' invented history.

I opened the January/February issue of Archaeology today and eagerly turned to “A Letter from Macedonia” only to discover that it was actually a letter from ancient Paionia – the land north of Mt. Barmous and Mt. Orbelos. Livy’s account of the creation of the Roman province of Macedonia (45.29.7 and 12) makes clear that the Paionians lived north of those mountains (which form today the geographically natural northern limits of Greece) and south of the Dardanians who were in today’s Kosovo. Strabo (7. frag 4) is even more succinct in saying that Paionia was north of Macedonia and the only connection from one to the other was (and is today) through the narrow gorge of the Axios (or Vardar) River. In other words, the land which is described by Matthew Brunwasser in his “Owning Alexander” was Paionia in antiquity.


While it is true that those people were subdued by Philip II, father of Alexander, in 359 B.C. (Diodorus Siculus 16.4.2), they were never Macedonians and never lived in Macedonia. Indeed, Demosthenes (Olynthian 1.23) tells us that they were “enslaved” by the Macedonian Philip and clearly, therefore, not Macedonians. Isokrates (5.23) makes the same point. Likewise, for example, the Egyptians who were subdued by Alexander may have been ruled by Macedonians, including the famous Cleopatra, but they were never Macedonians themselves, and Egypt was never called Macedonia (and so far as I can tell does not seek that name today).

Certainly, as Thucydides (2.99) tells us, the Macedonians had taken over “a narrow strip of Paionia extending along the Axios river from the interior to Pella and the sea”. One might therefore understand if the people in the modern republic centered at Skopje called themselves Paionians and claimed as theirs the land described by Thucydides.

But why, instead, would the modern people of ancient Paionia try to call themselves Macedonians and their land Macedonia? Mr. Brunwasser (p. 55) touches on the Greek claims “that it implies ambitions over Greek territory” and he notes that “the northern province of Greece is also called Macedonia.” Leaving aside the fact that the area of that northern province of modern Greece has been called Macedonia for more than 2,500 years (see, inter alios, Herodotus 5.17; 7.128, et alibi), more recent history shows that the Greek concerns are legitimate. For example, a map produced in Skopje in 1992 (Figure 1) shows clearly the claim that Macedonia extends from there to Mt. Olympus in the south; that is, combining the ancient regions of Paionia and Macedonia into a single entity. The same claim is explicit on a pseudo-bank note of the Republic of Macedonia which shows, as one of its monuments, the White Tower of Thessalonike, in Greece (Figure 2). There are many more examples of calendars, Christmas cards, bumper-stickers, etc., that all make the same claim.

Further, Mr. Brunwasser has reported with approval (International Herald Tribune 10/1/08) the work of the “Macedonian Institute for Strategic Research 16:9”, the name of which refers “to Acts 16:9, a verse in the New Testament in which a Macedonian man appears to the Apostle Paul begging him: ‘Come over into Macedonia, and help us.’” But where did Paul go in Macedonia? Neapolis (Kavala), Philippi, Amphipolis, Apollonia, Thessaloniki, and Veroia (Acts 16:11-17:10) all of which are in the historic Macedonia, none in Paionia. What claim is being made by an Institute based in Skopje that names itself for a trip through what was Macedonia in antiquity and what is the northern province of Greece today?

I wonder what we would conclude if a certain large island off the southeast coast of the United States started to call itself Florida, and emblazoned its currency with images of Disney World and distributed maps showing the Greater Florida.
Certainly there was no doubt of the underlying point of “Macedonia” in the mind of U.S. Secretary of State Edward Stettinius on December 26, 1944, when he wrote:

“The Department [of State] has noted with considerable apprehension increasing propaganda rumors and semi-official statements in favor of an autonomous Macedonia, emanating principally from Bulgaria, but also from Yugoslav Partisan and other sources, with the implication that Greek territory would be included in the projected state. This government considers talk of Macedonian ”nation”, Macedonian “Fatherland”, or Macedonian “national consciousness” to be unjustified demagoguery representing no ethnic nor political reality, and sees in its present revival a possible cloak for aggressive intentions against Greece.”
[Source: U.S. State Department, Foreign Relations vol viii, Washington, D.C., Circular Airgram (868.014/26Dec1944)]

Mr. Brunwasser (a resident of Bulgaria), however, goes on to state, with apparent distain, that Greece claims “Alexander III of Macedon (Alexander the Great) . . . as Greek.”

This attitude mystifies me. What is there to “claim”? Alexander’s great-great-great grandfather, Alexander I, was certified as Greek at Olympia and, in the words of the father of history “I happen to know that [the forefathers of Alexander] are Greek” (Herodotus 5.22). Alexander’s father, Philip, won several equestrian victories at Olympia and Delphi (Plutarch, Alexander 4.9; Moralia 105A), the two most Hellenic of all the sanctuaries in ancient Greece where non-Greeks were not allowed to compete. If Philip was Greek, wasn’t his son also Greek?

When Euripides – who died and was buried in Macedonia (Thucydides apud Pal. Anth. 7.45; Pausanias 1.2.2; Diodorus Siculus 13.103) – wrote his play Archelaos in honor of the great-uncle of Alexander, did he write it in Slavic? When he wrote the Bacchai while at the court of Archelaos did he not write it in Greek even as it has survived to us? Or should we imagine that Euripides was a “Macedonian” who wrote in Slavic (at a date when that language is not attested) which was translated into Greek?

What was the language of instruction when Aristotle taught Alexander? What language was carried by Alexander with him on his expedition to the East? Why do we have ancient inscriptions in Greek in settlements established by Alexander as far away as Afghanistan, and none in Slavic? Why did Greek become the lingua franca in Alexander’s empire if he was actually a “Macedonian”? Why was the New Testament written in Greek rather than Slavic?

On page 57 of the so-called “Letter from Macedonia” there is a photograph of the author standing “before a bronze statue of Alexander the Great in the city of Prilep.” The statue is patently modern, but the question is whether the real historic Alexander could have read the Slavic inscription beneath his feet. Given the known historic posterity of Slavic to Greek, the answer is obvious.

While Mr. Brunwasser’s reporting of the archaeological work in Paionia is welcome, his adoption and promotion of the modern political stance of its people about the use of the name Macedonia is not only unwelcome, it is a disservice to the readers of Archaeology who are, I imagine, interested in historic fact. But then, the decision to propagate this historical nonsense by Archaeology – a publication of the Archaeological Institute of America - is a disservice to its own reputation.

Let it be said once more: the region of ancient Paionia was a part of the Macedonian empire. So were Ephesos and Tyre and Palestine and Memphis and Babylon and Taxila and dozens more. They may thus have become “Macedonian” temporarily, but none was ever “Macedonia”.

Allow me to end this exegesis by making a suggestion to resolve the question of the modern use of the name “Macedonia.” Greece should annex Paionia – that is what Philip II did in 359 B.C. And that would appear to be acceptable to the modern residents of that area since they claim to be Greek by appropriating the name Macedonia and its most famous man. Then the modern people of this new Greek province could work on learning to speak and read and write Greek, hopefully even as well as Alexander did.


Sincerely,

Stephen G. Miller

Professor Emeritus,
University of California, Berkeley

PS: For a more complete examination of the ancient evidence regarding Paionia, see I. L. Merker,“The Ancient Kingdom of Paionia,” Balkan Studies 6 (1965) 35-54

My only disagreement with the good professor, is that the Slavs of FYROM do not merit either the name of Macedonians or of Paionians, since they have no ethnic link to either ancient people. They are in fact, largely Bulgarians, but since some of them don't like (or are afraid) to be called such, they should be called Slavopaionians, as is appropriate for Slavs inhabiting the ancient region of Paionia.

Waist-to-Hip Ratio across cultures

CURRENT ANTHROPOLOGY Volume 49, Number 6, December 2008
DOI: 10.1086/593036

Waist-to-Hip Ratio across Cultures: Trade-Offs between Androgen- and Estrogen-Dependent Traits


Elizabeth Cashdan

Abstract

A gynoid pattern of fat distribution, with small waist and large hips (low waist-to-hip ratio, or WHR) holds significant fitness benefits for women: women with a low WHR of about 0.7 are more fecund, are less prone to chronic disease, and (in most cultures) are considered more attractive. Why, then, do nearly all women have a WHR higher than this putative optimum? Is the marked variation in this trait adaptive? This paper first documents the conundrum by showing that female WHR, especially in non-Western populations, is higher than the putative optimum even among samples that are young, lean, and dependent on traditional diets. The paper then proposes compensating benefits to a high WHR that can explain both its prevalence and variation in the trait. The evidence indicates that the hormonal profile associated with high WHR (high androgen and cortisol levels, low estrogens) favors success in resource competition, particularly under stressful and difficult circumstances, even though this carries fitness costs in fecundity and health. Adrenal androgens, in particular, may play an important role in enabling women to respond to stressful challenges.

Link

Nicholas Christakis on the Anthroposphere

An interesting answer from the Edge World Question Center 2009. The part in italics reminds me of a previous post I made on Rise of diseases in modern societies is not (usually) due to genetic or environmental factors:

This is a simple consequence of the one reality of life, namely death. The total mortality of the population is always 100%, as we all eventually die. Therefore the prevalence of a particular disease (which brings us closer to death) does not depend exclusively on factors (genetic or environmental) that cause the disease. It also depends on other diseases or lethal factors which might beat them to the punch.

In previous centuries for example, death during childbirth, tuberculosis, death in war, famine etc. were more prevalent. Thus, they took a larger part of the 100% pie. Degenerative diseases were thus correspondingly less important, because irrespective of genes or environments affecting them, we used to die of other causes.

Here is Christakis on the Anthroposphere:

NICHOLAS A. CHRISTAKIS
Physician and social scientist, Harvard

THE ANTHROPOSPHERE

...

The global population stood at one million at 10,000 BC, 50 million at 1,000 BC, and 310 million in 1,000 AD. It stood at about one billion in 1800, 1.65 billion in 1900, and 6.0 billion in 2000. Analysis of these macro-historical trends in human population usually focuses on this population growth and on the "demographic transition" underlying it.

During the first stage of the demographic transition, life—as Hobbes rightly suggested—was nasty, brutish, and short. There was a balance between birth rates and death rates, and both were very high (30-50 per thousand people per year). The human population grew less than 0.05% annually, with a doubling time of over 1,000 years. This state of affairs was true of all human populations everywhere until the late 18th century.

Then, during the second stage, the death rate began to decline—first in northwestern Europe, but then spreading over the next 100 years to the south and east. The decline in the death rate was due initially to improvements in food supply and in public health, both of which reduced mortality, particularly in childhood. As a consequence, there was a population explosion.

During the third stage, birth rates dropped for the first time in human history. The prior decline in childhood mortality probably prompted parents to realize they did not need as many children; and increasing urbanization, increasing female literacy, and (eventually) contraceptive technology also played a part.

Finally, during the fourth stage—in which the developed world presently finds itself—there is renewed stability. Birth and death rates are again in balance, but now both are relatively low. Causes of mortality have shifted from the pre-Modern pattern dominated by infectious diseases, perinatal diseases, and nutritional diseases, to one dominated by chronic diseases, mental illnesses, and behavioral conditions.

This broad story, however, conceals as much as it reveals. There are other demographic developments worldwide beyond the increasing overall size of the population, developments that are still unfolding and that matter much more. Changes in four aspects of population structure are key: (1) sex ratio, (2) age structure, (3) kinship systems, and (4) income distribution.

Sex ratios are becoming increasingly unbalanced in many parts of the world, especially in China and India (which account for 37% of the global population). The normal sex ratio at birth is roughly 106 males for every 100 females, but it may presently be as high as 120 for young people in China, or as high as 111 in India. This shift, much discussed, may arise from preferential abortion or the neglect of baby girls relative to boys. Gender imbalance may also have other determinants, such as large-scale migration of one or the other sex in search of work. This shift has numerous implications. For example, given the historical role of females as caregivers to elderly parents, a shortage of woman to fill this role will induce large-scale social adjustments. Moreover, an excess of low-status men unable to find wives results in an easy (and large) pool of recruits for extremism and violence.

This shift in gender ratios may have other, less heralded implications, however. Some of our own work has suggested that this shift may actually shorten men’s lives, reversing some of the historic progress we have made. Across a range of species, skewed sex ratios result in intensified competition for sexual partners and this induces stress for the supernumerary sex. In humans, it seems, a 5% excess of males at the time of sexual maturity shortens the survival of men by about three months in late life, which is a very substantial loss.

On the other hand, the population worldwide is getting older, especially in the developed world. Globally, the UN estimates that the proportion of people aged 60 and over will double between 2000 and 2050, from 10% to 21%, and the proportion of children will drop from 30% to 21%. This change also has numerous implications, including on the "dependency ratio," meaning that fewer young people are available to provide for the medical and economic needs of the elderly. Much less heralded, however, is the fact that war is a young person’s activity, and it is entirely likely that, as populations age, they may become less aggressive.

The changing nature of kinship networks, such as the growth in blended families—whether due to changing divorce patterns in the developed world or AIDS killing off parents in Africa—has implications for the network of obligations and entitlements within families. Changing kinship systems in modern American society (with complex mixtures of remarried and cohabiting couples, half-siblings, step-siblings, and so on) are having profound implications for caregiving, retirement, and bequests. Who cares for Grandma? Who gets her money when she dies?

Finally, it is not just the balance between males and females, or young and old, that is changing, but also the balance between rich and poor. Income inequality is reaching historic heights throughout the world. The top 1% of the people in the world receives 57% of the income. Income inequality in the US is presently at its highest recorded levels, exceeding even the Roaring Twenties. And while economic development in China has proceeded with astonishing rapidity, income is not evenly distributed; the prospects for conflict in that country as a result seem very high in the coming decades.

Lacking any real predators, a key feature of the human environment is other humans. In our rush to focus on threats such as global warming and environmental degradation, we should not overlook this fact. It is well to look around at who, and not just what, surrounds us. Population structure will change everything. Our health, wealth, and peace depend on it.

Inbreeding depression and IQ

Intelligence doi:10.1016/j.intell.2008.10.007

Inbreeding depression and IQ in a study of 72 countries

Michael A. Woodley

Abstract

In this ecological study, a robust negative correlation of r = − .62 (P less than .01) is reported between national IQs and consanguinity as measured by the log10 transformed percentage of consanguineous marriages for 72 countries. This correlation is reduced in magnitude, when IQ is controlled for GDP per capita (r = − .41, P less than .01); education index (r = − .40, P less than .01); and democracy index (r = − .42, P less than .01). Multiple regression analysis revealed that in the absence of the democracy index; percentage consanguineous marriages, education index and GDP per capita all exhibited stable final standardized β coefficients, however consanguinity had the least impact (β = 0, P greater than .05) whereas GDP per capita had the highest (β = .35, P greater than .01). This result is interpreted in light of cultural feedback theory, whereby it is suggested that consanguinity could subtly influence IQ at larger scales as a result of small IQ handicaps bought about through inbreeding being amplified into much larger differences through their effect on factors that maximize IQ such as access to education and adequate nutrition. Finally, consideration is given to future potential research directions.

Link

Female life expectancy vs. Female Birth Rate

Evolution and Human Behavior doi:10.1016/j.evolhumbehav.2008.08.002

Sex difference in life span affected by female birth rate in modern humans

Alexei A. Maklakov

Abstract

Sex differences in life span are common in different taxa, including primates, but not well understood. Theory and comparative evidence suggest that differential costs of reproduction between the sexes may explain the differences in sex-biased mortality across large taxonomic groups. The level of sex-specific reproductive effort may thus affect the difference in life span across populations. Modern humans (Homo sapiens), generally show the typical mammalian pattern of male-biased mortality. Here, I asked whether the differences in female birth rates between countries affect the sex difference in life span. I used the data on male and female life span and female birth rate in different countries from publicly available databases, while controlling for geographic and economic factors. The analysis suggests that female birth rate explains 17% of the variation in relative sex differences in life span across countries. Low female birth rate results in females living relatively longer than males. These data suggest that a simple biological factor—female birth rate—may explain a significant part of the variation in sex differences in life span across human populations.

Link

Ethnic nationalism reappraised

Jerry Z. Muller has an interesting article in Foreign Affairs, titled Us and Them: The Enduring Power of Ethnic Nationalism, in which he argues that the reason why Europe has enjoyed such a long period of peace after World War II was the fact that post-war states were largely ethnically homogeneous. Thus, he argues, peace was not so much the result of European nations' "overcoming" their nationalism, but rather its fulfillment, i.e. the creation of nation states dominated by a single ethnic group.

It's a fairly interesting piece, touching among other things on the resurgence of nationalism after the Cold War in the few places in Europe (e.g. the former Yugoslavia and Soviet Union) where national and ethnic borders did not coincide, the distinction between ethnic and civic nationalism, and the challenges that ethnic nationalism faces in an age of immigration.