linkfest: 05/27/14

Quick Questions for Peter and Rosemary Grant“There is widespread misunderstanding about evolution; that it occurs extremely slowly and therefore cannot be studied in a person’s lifetime. This was the view of Charles Darwin. Many biologists and others now know that this is not correct…. The idea that animals as large as birds might evolve before our eyes is not so well known, yet our study in the entirely natural world of Daphne Major island has revealed this does in fact happen when there is a change in the environment, and it takes place over a period as short as a year, and repeatedly.” – h/t billare!

Is DNA Multilingual?“The genetic code has traditionally been viewed as a universal set of instructions, exquisitely tuned to maintain robust stability and allow evolution-sustaining mutations. But the pervasive occurrence of recoded stop codons, and the backchannel crosstalk between microbes and viruses, paints a more intricate picture of multilingual genetic instructions.”

Jelly genome mystery“The uniqueness of this ctenophore’s nervous system leads Moroz and his team to argue that it must have evolved independently, after the ctenophore lineage branched off from other animals some 500 million years ago.”

Genomic divergence in a ring species complex“Ring species provide particularly clear demonstrations of how one species can gradually evolve into two, but are rare in nature…. Here we use genome-wide analyses to show that, although spatial patterns of genetic variation are currently mostly as expected of a ring species, historical breaks in gene flow have existed at more than one location around the ring, and the two Siberian forms have occasionally interbred.” – h/t razib!

Natural selection and infectious disease in human populations“The ancient biological ‘arms race’ between microbial pathogens and humans has shaped genetic variation in modern populations, and this has important implications for the growing field of medical genomics. As humans migrated throughout the world, populations encountered distinct pathogens, and natural selection increased the prevalence of alleles that are advantageous in the new ecosystems in both host and pathogens. This ancient history now influences human infectious disease susceptibility and microbiome homeostasis, and contributes to common diseases that show geographical disparities, such as autoimmune and metabolic disorders.”

High genetic differentiation between populations often driven by classic selective sweeps“‘We demonstrate that while sites of low differentiation represent sampling effects rather than balancing selection, sites showing extremely high population differentiation are enriched for positive selection events and that one half may be the result of classic selective sweeps. Among these, we rediscover known examples, where we actually identify the established functional SNP, and discover novel examples including the genes ABCA12, CALD1 and ZNF804, which we speculate may be linked to adaptations in skin, calcium metabolism and defense, respectively. Conclusions: We have identified known and many novel candidate regions for geographically restricted positive selection, and suggest several directions for further research.'” – @dienekes’.

Mendelian-Mutationism: The Forgotten Evolutionary Synthesis – h/t neuroskeptic! who tweeted: “Did geneticists ‘crack’ the secret of evolution much earlier than believed?”

this one’s for linton!: Why Marrying Your Cousin May Pay Off“In line with previous findings, the researchers found that among non-foraging societies, a couple’s relatedness was linked with having more surviving children. But among foraging societies, the opposite was true: More-closely related spouses had fewer surviving children. Furthermore, the more family intermarriage in a society, the greater the benefit of intermarrying on the number of children couples had. In other words, in societies in which people frequently married their relatives, intermarrying showed a stronger link to having more children.”

The Closest of Strangers“[I]dentical twins who are aunts and uncles invest more in caring for the children of their twins (their ‘genetic’ sons and daughters) than do fraternal twins.”

Why Do Honor Killings Defy the First Law of Homicide? And Will Smaller Families Lead to Fewer Of Them? – h/t tom farsides! – previously: inclusive inclusive fitness.

Genetic and educational assortative mating among US adults“We find that spouses are more genetically similar than two individuals chosen at random but this similarity is at most one-third the magnitude of educational similarity.”

Irish fair skin can be traced to India and the Middle East“A major new US study at Penn State University has found that Europeans’ light skin stems from a gene mutation from a single person who lived 10,000 years ago…. Keith Cheng from Penn State College of Medicine reported that one amino acid difference in the gene SLC24A5 is a key contributor to the skin color difference between Europeans and West Africans…. ‘The mutation in SLC24A5 changes just one building block in the protein, and contributes about a third of the visually striking differences in skin tone between peoples of African and European ancestry, he said…. The mutation, called A111T, is found in virtually everyone of European ancestry. A111T is also found in populations in the Middle East and Indian subcontinent, but not in high numbers in Africans. All individuals from the Middle East, North Africa, East Africa and South India who carry the A111T mutation share traces of the ancestral genetic code. According to the researchers, this indicates that all existing instances of this mutation originate from the same person.” – h/t 23andMe!

The puzzle of European hair, eye, and skin color“The physical appearance of Europeans seems to result from a selection pressure that acted primarily on women and only secondarily on men. This is especially true for highly visible traits on or near the face—the focus of visual attention.” – from peter frost.

The Dark Triad of Personality – special issue of Personality and Individual Differences. – h/t claire lehmann!

Heritability of brain volume change and its relation to intelligence“Human brain volumes change throughout life, are highly heritable, and have been associated with general cognitive functioning…. Results show that changes in volumes of total brain (mean=-6.4ml; -0.5% loss), cerebellum (1.4ml, 1.0% increase), cerebral white matter (4.4ml, 0.9% increase), lateral ventricles (0.6ml; 4.8% increase) and in surface area (-19.7cm2, -1.1% contraction) are heritable (h2=43%; 52%; 29%; 31%; and 33%, respectively). An association between IQ (available for 91 participants) and brain volume change was observed, which was attributed to genes involved in both the variation in change in brain volume and in intelligence. Thus, dynamic changes in brain structure are heritable and may have cognitive significance in adulthood.”

Cognitive abilities amongst the Sámi population“Lapps have an IQ around 100.8 are tilted towards visuospatial ability and away from verbal ability.” – from elijah armstrong, michael woodley the younger, and richard lynn. edit: original paper here on elijah’s blog! (^_^)

The Flynn Effect in a Nutshell – from elijah.

Does brain structure determine your political views?“‘People like to believe that their own political beliefs are rational, that they’re a sensible response to the world around them, so when we come along and say, “Maybe there are these predispositions, influential but perhaps not fully in your conscious awareness,” that’s not the way we like to view our own political beliefs.'” – h/t mr. robert ford!

Sex-Related Neuroanatomical Basis of Emotion Regulation Ability“Behavioral research has demonstrated that males have a higher capability of regulating their own and others’ emotions than females; however, little is known about the sex-specific brain mechanisms involved in emotion regulation ability…. we found the sex differences in the neuroanatomical basis of emotion regulation ability. Males showed a stronger positive relation between emotion regulation ability and regional gray matter volume (rGMV) in the right dorsolateral prefrontal cortex. In contrast, females demonstrated a stronger positive relation between emotion regulation ability and rGMV in an anatomical cluster that extends from the left brainstem to the left hippocampus, the left amygdala and the insular cortex.”

More Maps of the American Nations – from jayman.

Privilege and Morality“Our species isn’t good at nuance. The ‘privilege’ debate will and must take place in a morally charged context. It is not possible to sanitize the discussion by scrubbing it free of moral emotions. That is one of the many reasons why it is so important to understand what morality is and why it exists. It does not exist as a transcendental entity that happened to pop into existence with the big bang, nor does it exist because the Big Man upstairs wants it that way. It exists because it evolved.” – from helian.

Economic Growth & Human Biodiversity“Economic growth in lower-IQ countries does not invalidate either the reality of IQ differences between countries or the persistence of those disparities.” – from pseudoerasmus.

Good Fences: The Importance of Setting Boundaries for Peaceful Coexistence“Switzerland is recognized as a country of peace, stability and prosperity. This is surprising because of its linguistic and religious diversity that in other parts of the world lead to conflict and violence. Here we analyze how peaceful stability is maintained. Our analysis shows that peace does not depend on integrated coexistence, but rather on well defined topographical and political boundaries separating groups, allowing for partial autonomy within a single country. In Switzerland, mountains and lakes are an important part of the boundaries between sharply defined linguistic areas. Political canton and circle (sub-canton) boundaries often separate religious groups. Where such boundaries do not appear to be sufficient, we find that specific aspects of the population distribution guarantee either sufficient separation or sufficient mixing to inhibit intergroup violence according to the quantitative theory of conflict. In exactly one region, a porous mountain range does not adequately separate linguistic groups and that region has experienced significant violent conflict, leading to the recent creation of the canton of Jura.”

Was Territoriality Important in the Pleistocene? A Commentary on Johnson and Toft – @peter turchin’s.

Southern Europe is suspicious: the evolution of trust in the EU – ess and wvs results.

Trust and In-Group Favoritism in a Culture of Crime [pdf] – h/t ben southwood! who tweeted: “Areas in Palermo with high Mafia involvement have lower generalised trust but higher in-group favouritism.”

In dogs’ play, researchers see honesty and deceit, perhaps something like morality – woof!

What is Phonemic Diversity? — And Does It Prove the Out-of-Africa Theory? – h/t james winters!

How a Protestant spin machine hid the truth about the English Reformation“It seems that in 1533, the year of Henry’s break from Rome, traditional Catholicism was the religion of the vast majority of the country. And in most places it was absolutely thriving. It had developed a particularly English flavour, with a focus on the involvement of ordinary people in parish churches, village greens, plays, and pageants – much of which seemed to involve a good deal of community parties, dancing, and drinking. It is true that English religion in the early 1500s was not especially studious or erudite. The people did not spend hours a day in biblical studies, contemplation, and moralising in the manner of the more intense European reformers. But England had a nationally cohesive spirituality that was alive and exuberant, with a distinctly community feel…. The conclusion of this modern grassroots scholarship is that bulldozing the Catholic Church off the face of medieval England was not a ‘bottom up’ revolution in which Henry merely acquiesced to his people’s wishes by throwing off a widely hated foreign domination. To the contrary, it looks increasingly like Henry and his circle imposed the Reformation ‘top down’, unleashing 100 years of deep anger and alienation that was only overcome by sustained politicking and ruthless force.” – h/t william briggs!

bonus: “No Oxygen? No Problem!” Says Squid That Can Shut Down Its Metabolism – h/t kyle hill!

bonus bonus: A Theory on How Flightless Birds Spread Across the World: They Flew There

bonus bonus bonus: Chicken project gets off the ground“Effort aims to unravel the history of bird’s domestication.” – cluck!

(note: comments do not require an email. humble humboldt squid!)

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pathogens and consanguinity and democracy

so at long last, the final point from the woodley & bell paper that i want to draw attention to (there are lots more neat points in the paper that you can read for yourself here): pathogens and consanguinity and democracy.

yesterday’s post was about how there seems to be some sort of a connection between the frequencies of pathogens in any given environment and consanguineous matings. it’s not the strongest of connections, but it seems to be there (i’m convinced anyway).

woodley & bell found that pathogen load does, indeed, have an impact on how (liberally) democratic societies are or not — but via consanguinity. there is a correlation between pathogen load and presence/absence/degree of democracy, but it’s not a direct one. here are their path analyses from their paper (more details in previous post). follow the arrows:

so it’s: pathogen load -> consanguinity -> democracy (or not).

i’d amend that a bit and say it’s: pathogen load + other social/economic factors -> consanguinity -> democracy (or not).

if i were to amend it even further in a theorizing sort-of way (that’s theorize with a small “t” not a big one), i’d say it’s:

pathogen load + other social/economic factors -> long-term consanguinity/endogamous matings -> democracy (or not) and/or a whole lot of other neat things like individualism and low levels of corruption and nepotism and so on and so forth.

that is all! (^_^)

previously: consanguinity and democracy and consanguinity and islam and democracy

(note: comments do not require an email. how to reduce pathogen load in the population.)

pathogens and consanguinity

remember the woodley & bell paper about the connections between consanguineous matings and democracy (or lack of) that i said i was going to post a lot about? and then i got distracted? well, let’s get back to it.

by way of introducing woodley & bell’s idea that pathogens (and consanguinity) and democracy don’t go together, the last post in this thread of posts had to do with possible connections between pathogens and individualistic vs. collectivistic societies — i.e. seems like the more pathogens in your environment, the more collectivistic (ethnocentric, conforming, suspicious of outsiders) your society is going to be. now i want to look at one more paper before i get back to consangunity and democracy.

in On the Adaptive Origins and Maladaptive Consequences of Human Inbreeding: Parasite Prevalence, Immune Functioning, and Consanguineous Marriage [opens pdf], hoben, et al., present their finding of a correlation between frequencies of pathogens and frequencies consanguineous marriages in various societies around the world. it’s not a huge correlation — r = 0.39 — but it is there. the more pathogens you’ve got in your environment, the more likely you are to practice cousin marriage. kinda/sorta.

like the paper in the last post, these researchers worked from the consang.net data and the historic pathogen data from this paper. hoben, et al., didn’t include any nifty charts in their paper, and since i like my data served up visually, i made a chart of my own (click on image for LARGER view):

x-axis=their pathogen index. positive numbers (z-scores) indicate higher frequencies of pathogens; negative numbers, lower frequencies. bosnia-herzegovina has a z-score of 0; england has a z-score of -1.01. burkina faso has the highest z-score at 1.16. canada has the lowest z-score at -1.31.

y-axis=weighted mean consanguineous marriage rates.

i think there is a broad, general pattern here. and it makes some sense. as the authors say:

“[I]ncreased homozygosity and other genetic coadaptation that results from inbreeding can facilitate highly specific forms of immunological resistance to local parasites, and … these immunological benefits will be most pronounced under ecological circumstances in which endemic pathogens are more highly prevalent (Denic et al., 2008; Denic and Nicholls, 2007; Fincher and Thornhill, 2008a, b; Shields, 1982)…. [O]ur study indicates that, under certain circumstances (i.e., high pathogen prevalence), inbreeding may have advantages that outweigh its costs.”

but the correlation was not that high. and i think part of the reason for that is “technical” — that is that there are some “glitches” in the consang.net data that the researchers didn’t take into account.

take brazil, for instance. high on the pathogen index (0.930) but pretty low consanguinity-wise (4.348%). but that’s because brazil was fairly recently settled by westerners (and blacks and japanese) who brought roman catholic traditions with them when they settled there — in other words, cousin marriage prohibitions. so of course the consanguinity and pathogen frequencies don’t match very well for brazil. what should be looked at are native brazilian consanguinity rates which are more like 13% (only one study, unfortunately — see page 3** [opens pdf]).

the authors have also calculated the consanguinity data for slovakia as 11.618%, but that includes gypsies [pg. 10 – opens pdf] who are consanguineous wherever they go, so that is undoubtedly skewing the numbers for slovakia. the consanguinity figures for czechoslovakia are more like 0.2% [pg. 1 – opens pdf].

the BIG outliers, though, are the arabs and all their middle eastern/north african/south asian muslim buddies. they are the ones throwing off the correlation completely. i’m talking about most of the dots that are right in the middle of the chart: 0.5000 or lower on the pathogen index (so, not a lot of pathogens) but above the 20% consanguinity rate:

regionconsang. ratepathogen index
uae – 36% – -0.450
kuwait – 51.7% – -0.340
iran – 32.2% – -0.150
oman – 35.9% – -0.140
pakistan – 51% – 0.020
saudi arabia – 38.4% – 0.040
libya – 37.6% – 0.040
jordan – 31.2% – 0.160
afghanistan – 55.4% – 0.230
syria – 31.6% – 0.300
lebanon – 26.6% – 0.360
yemen – 35% – 0.410
egypt – 31% – 0.440

these societies are amongst those that have the highest consanguinity rates, and yet some of their pathogen index scores are very low. the united arab emirates, for instance, scores like france (-0.460) or the republic of ireland (-0.450). qatar has got the exact same score as australia (-0.250). and saudi arabia and pakistan have lower scores than italy (0.160).

clearly having pathogens in the environment is not the whole story when it comes to the push towards cousin marriage. and hoben, et al., don’t claim that either:

“To complement those partial explanations [economic, etc.] for the persistence of consanguineous marriages, in the present research we offer an additional explanation that we label the ‘parasite hypothesis of inbreeding.'”

a complementary explanation. i agree! prolly the most fundamental, underlying one i would guess.

previously: consanguinity and democracy and consanguinity and islam and democracy and pathogens and culture

(note: comments do not require an email. **note to english readers: sorry, no half-naked women on that page 3.)

pathogens and culture

the final point that i want to look at from the woodley & bell paper on consanguinity and democracy is their finding that pathogen load affects consanguinity (which, in turn, affects democracy) in societies. before i do that, though, i want to back up and look at pathogens and culture.

in 2008, fincher, et al., published their findings [opens pdf] of an apparent relationship between individualistic vs. collectivist societies and pathogen load. generally, the more pathogens in your environment, the more collectivist — ethnocentric, conforming — you’re gonna be since limiting your interactions with strangers will help to reduce your chances of catching some lethal disease. and vice versa.

i like it! (^_^)

here’s a nice little chart from the paper showing the correlation between individualism (taken from hofstede 2001) and historical pathogen prevelance (the authors explain how they came up with their pathogen index on pgs. 1280-81):

two of the et al. guys, murray and schaller, expanded the historic pathogen index in a paper published in 2010 [opens pdf]. the index (or, rather, indices ’cause there’s two of them) sums up the historic disease prevalence for 230 nations or geopolitical regions. they offer (pg. 102) a nice table summarizing several different studies which found correlations between pathogen load and things like individualism vs. collectivism, extraversion, openness and democratization (click on chart for LARGER view):

again, in general, the more pathogens, the more cultural/behavioral “restrictions.” (but the spicier the food! mmmmm!)

more on all this anon!

previously: consanguinity and democracy and consanguinity and islam and democracy

(note: comments do not require an email. hi there!)