i offered up this little pop quiz back in 2013, and i’m resurrecting it ’cause i want to talk about this some more. first, the quiz:
in which group does the flower at the bottom belong: group a or group b?
feel free to leave your answer in the comments and — only if you like — the reason(s) for your choice and/or your ethnic background. (^_^) (you don’t have to be specific — you can say “eastern” or “southern” european, etc., if you prefer.)
a lot of you responded to this last time ’round — no need to do so again! (^_^)
this is (obviously) in nisbett’s The Geography of Thought territory.
that is all. for now!
previously: do you think like a westerner?
(note: comments do not require an email. jackass [penguin].)
i’ve hinted around a few times now that i think — going by some things that i’ve read — that the historic mating patterns of ashkenazi jews (i.e. whether or not they married close cousins and/or practiced uncle-niece marriage) were quite different between western vs. eastern ashkenazis. quoting myself:
“wrt ashkenazi jews: i *strongly* suspect (but Further Research is RequiredTM) that there are two mating pattern histories here — western vs. eastern ashkenazi jews. western ashkenazi jews have, i think, avoided close cousin marriage since the medieval period almost to the same degree as the rest of western europeans. eastern ashkenazi jews — the ones in poland/russia — did not. again, i’m not at all sure about this — this is just what i’ve gleaned from my readings so far. (i will be posting on this one of these days.)
“where western ashkenazi jews differ from the rest of the western european populace is that they were not squeezed through the manorialism meat grinder. in that regard, they must’ve experienced some different selection pressures during the medieval period.”
i first came across this idea — quite a while ago now — in my favorite book, Why Europe?, by medieval and family historian michael mitterauer. he says on pg. 72:
“We find it difficult to comprehend today just how preoccupied the era [the middle ages] was with the fear of incest — and not only in the various Christian churches but in Jewish circles as well.”
he references himself on that — “Christentum und Endogamie” in Historisch-anthropologische Familienforschung — but i haven’t read it yet. one of these days, i just might order it from amazon…and dig out my german-english dictionary.
mitterauer is supported in this by one kenneth r. stow in “The Jewish Family in the Rhineland in the High Middle Ages: Form and Function” [pgs. 1095-96]:
“Unlike Christians, Jews were free to marry cousins and nieces; in the Islamic East, first-cousin marriage among Jews was the norm. In the Rhineland, however, such marriages were somewhat of an exception. This difference may be deduced from the universally accepted Communal Ordinance (*Taqqanah*) proposed by Jacob Tam, the most imposing Jewish authority of his day (d. 1171), on the return of the dowry should the bride die without issue during the first year of marriage. Fathers, the ordinance propounds, should not lose both their daughters and their wealth in one blow. If most marriages had been between first cousins, the respective in-laws, who would also have been siblings, would normally have found ways of resolving issues of money among themselves without the need for legal sanctions. The Responsa (*consilia*) literature, too, legal questions and answers pertaining to actual litigations, supports this conclusion. Responsa may represent exceptions, but they are useful in terms of their specifics or when their decisions reflect precendent or common practices. Thus, in one case, an executor, who was (it should be stressed for its own importance) not a relative of the deceased, married his ward to *his* brother. The brothers of the bride protested, not because she had been married to a non-relative but because they were concerned with the suitability of the match. Had marriage between cousins been the rule, it is doubtful that an executor, especially one who was not a relative, would have dared to violate it.”
so, stow doesn’t have hard-and-fast data on marriage types here — he’s making a deduction — but i think it’s a good one. what i find particularly persuasive is the fact that the family type of these medieval rhineland jews was primarily nuclear (or stem). in other words, according to stow, just like the broader western european population, medieval rhineland jews did *not* have clans. and that seems to be the general pattern: the more outbreeding, the smaller the family size.
fast forward to the nineteenth century (yes, that is an unacceptably large gap), in alsace-lorraine, the consanguinity rate amongst jews was 2.3% (whether that was first and second cousins or just first cousins, i don’t know) [see this post]. that is a very low rate by any standards. in comparison, though, the consanguinity rates for protestants in the region was 0.2% and for catholics it was roughly 1%, so the jewish cousin marriage rate was higher.*
if we move slightly to the east to what i infer must’ve been (at the time) the province of hohenzollern, we have these figures from steven m. lowenstein [“Decline and Survival of Rural Jewish Communities” in In Search of Jewish Community: Jewish Identities in Germany and Austria 1918-1933, footnote 44 on pg. 241]:
“In Hohenzollern, there was an 11 percent rate of marriage to relatives (5 percent to first cousins) among Jewish couples who died before 1922; of those still alive in 1922, the rate had increased to 22 percent (16 percent to first cousins). These rates were several times as high as the rates for Christian marriages. See Wilhelm Reutlinger, ‘Uber die Haufligkeit der Verwandtenehen bei Juden in Hohenzollern und uber Untersuchungen bei Deszendenten aus judischen Verwandtenehene,’ Archiv fur Rassen- un Gesellschaftsbiologie 14 (1922): 301-303, quoted by Marion Kaplan The Making of the Jewish Middle Class: Women, Family, and Identity in Imperial Germany (New York, 1991), p. 273 note 206.”
so, higher cousin marriage rates in this region amongst the cohort closest to the alsace-lorraine group above — 5-11% versus 2.3% (remembering that that latter figure might be just first cousins). and much higher rates post-1922, the author argues because jews were leaving the german countryside during this time period, so potential marriage partners were becoming scarce. still, while a 16% first cousin marriage rate is high for northern europe, it’s not even close to the 30%+ first cousin marriage rates in sicily in the 1960s! and the earlier 5-11% rate may have been more “normal” — hard to tell — Further Research is RequiredTM.
if you thought all that was vague, the info for jews in eastern europe is even less clear. (>.<) it's basically just anecdotal evidence — a lot of people saying that cousin marriage was very common in eastern european ashkenazi communities. i wrote a whole post about it: jewish mating patterns in nineteenth century russia. this quote is from Jewish Marriage and Divorce in Imperial Russia [pgs. 25-27]:
“Although data on consanguineous marriages in Russia are lacking, contemporaries claimed that they were ‘very common,’ largely because of the narrow circle of eligible partners for any given class of Jews. This geographic endogamy impelled one Jewish observer to write that ‘the expression “Kol Yisrael ahim” or “all Jews are brothers” is true in this sense, that Jews [who] belong to one strata of society and reside in one area, always find out that they are related when discussing their family backgrounds.’ The strategy of marrying relatives was particularly pronounced in small towns. It was due to concerns about family lineage, as well as to restrictions on geographic mobility (i.e., legal restrictions on residency, poor communications and transportation, and the high costs for travel).
“That observation indeed finds confirmation in the metrical records. These archival materials are unusually complete for Korostyshev, a small town in Kiev province with 2,657 Jewish residents in 1847. Unlike many Ukrainian towns where the metrical records were destroyed during World War II, Korostyshev preserved metrical books from the mid-nineteenth century to 1915, thus representing some of the most complete runs of Jewish metrical books in the entire Ukraine. Significantly, they reveal that most residents married locally — that is, to people from Korostyshev or, at most, from nearby villages and towns (Zhitomir, Berdichev, and Radomysl’). Still more striking were the marital bonds between small family networks — for example, the countless marriages among the Fuksmans, Gershengorens, Trakhtenbergs, and Ratners (all of whom lived in Korostyshev or nearby Zhitomir). Another network included the Vinikurs, Tsiponiuks, and Abrumovichs; this cluster overlapped with a group that included the Kagans, Umerskiis, and Peigers. And so on until, several decades later, many Korostyshev residents were distant or even close relatives. Devorah Baron’s description of small shtetl families was indeed perspicacious: ‘In our little town, families joined together by marriage ties often resembled well-fitted but separate sections of garment; all that was needed was the skillful hand that would join the seams.’”
in the late nineteenth century, russian-jewish leaders tried to do something about all this cousin marriage (these reformers were inspired by all the talk about the dangers of inbreeding generated by the darwins and galton, just as the japanese were) [pgs. 27-29]:
“In the late nineteenth century, Jewish reformers castigated this consanguinity as detrimental to family health. The developments in contemporary medicine (especially eugenics and clinical psychiatry) had a profound impace on public discourse; as physicians joined in, the debate on Jewish marriage became increasingly medicalized. ‘Owing to heredity,’ warned the ‘Evreiskii meditsinskii golos’ (The Jewish medical voice), ‘all physical defects appear in the offspring with particular force, since the definciencies of both parents are aggregated. Invoking Western science, Jewish physicians ascribed the increased rate of ‘nervous disorders,’ such as hysteria, epileptic seizures, imbecility, and insanity, among the Jewish in Russia to their pernicious inbreeding.
“Samuel Gruzenberg (1854-1909), who held a degree from the Medical-Surgical Academy in St. Petersburg, publicized a series of essays in an influential Jewish journal. Representing the views of the medical establishment, he warned parents that ‘nervous illness’ and hereditary diseases, such as blindness, deafness, and muteness, posed a threat not only to the immediate offspring but also to subsequent generations. Endogamous unions, he declared, also produced a large population with unhealthy ‘national physical features’ — namely, ‘a short [body], weak muscles, and especially … a high level of nervousness.’ Citing a study on army conscripts, he noted that nearly half of the Jewish recruits failed to meet the physical requirements and exhibited ‘extreme forms of the Jewish physical type.’
“It was no accident that Gruzenberg cited the Jewish recruit to demonstrate the evil of consanguineous marriages: the physiognomy of male offspring greatly concerned reformers. In contrast to the modern ideal of man, who displayed ‘virility, proportion, and self control,’ the asthenic Jewish conscript embodied all the traits of the effeminate Jew so despised in European society. Whereas Jewish society had long associated a pale, slender Jewish body with Torah scholarship and edelkayt (nobility), reformers now scorned this model as passive, cowardly, and feminine, a clear indication that the reforemers had embraced the new European construction of masculinity. The inbreeding affected not only the body but the mind: ‘Moral sickness and physical sickness were thought to be identical — the latter leaving an imprint on the body and face….’
“[T]his public debate did not reduce the frequency of consanguineous marriages….”
so, from all of this medical hysteria, i am guessing that the historic cousin marriage rates among jews in eastern europe were much higher than those in the west — at least in the nineteenth century.
sephardic jews have historically had much higher rates of consanguineous marriages than ashkenazi jews — up to 20% in some places according to joseph spitzer [pg. 160]. see also this post: jewish endogamy on mallorca. same with mizrahi jews — for example, the rate of consanguineous marriages among iranian jews in 1991 (first and second cousin plus uncle-niece marriages) was 25.4%.
it seems to me that jews — wherever they have lived (outside of judea/israel, i mean) — have generally copied the broader population’s mating patterns. in medieval western europe, they avoided close cousin marriage and, according to mitterauer, were very worried about incest in the same way that the rest of western europe was at the time. in eastern europe, though, they appear to have married their cousins with greater frequency, probably down through the centuries not unlike the rest of eastern europeans. in the nineteenth century, however, some eastern european jews began to be influenced by ideas on outbreeding coming from western europe. sephardic jews had high cousin marriage rates, just like southern europeans. and jews in north africa and the middle east have extremely high cousin marriage rates — same as the rest of the populations in those places. (for more on the histories of mating patterns in each of these regions, please see links to posts below ↓ in left-hand column under the “mating patterns in” series.)
long-term outbreeding (since the middle ages) of western ashkenazi jews would fit with the genetic evidence which indicates that ashkenazi jews are not inbred (see razib’s posts here and here). all the apparent historic cousin marriage of eastern ashkenazi jews would not fit with that. i’d like to see the genetic data (runs of homozygosity) for ashkenazis parsed out between eastern and western europe to see if any differences can be detected. my guess is that they should be there (there should be more roh in russian jews than in german jews), but i could be wrong.
so, the reasons i think that western european jews must’ve avoided close cousin marriage over the long-term, whereas in contrast eastern european jews did not, are:
– the scanty historic data (i will dig around for more of that);
– the somewhat supportive genetic data;
– the circumstantial evidence suggesting that jews have tended to copy the mating practices of their host populations;
– and that, by the high middle ages, western european jews did not have clans but, rather, had nuclear (or stem) families.
as i mentioned in my self-quote at the start of this post, though, european jews did not experience whatever selection pressures were connected to the bipartite manorialism of medieval europe. one of the things that i think was selected for via the manor system was the late marriage practices (i.e. delayed gratification) of northwest “core” europeans. western ashkenazi jews, on the other hand, continued to marry very young right into the early modern period, perhaps because they were never manorialized.
(yes, this is me gearing up to respond to professor kevin macdonald’s recent post On the HBD Chick Interview. i’ve got a couple of other “prep” posts i’d like to do first, though, before i get to my response. stay tuned! (^_^) )
*i also have some data for jewish cousin marriage rates in nineteenth century england, but shortly after writing that post, i decided that those data need to be disregarded. see this post for my reasons why.
(note: comments do not require an email. medieval german jews. and a duck!)
Stone Age skull from Kenya reveals astonishing human diversity – “A partial human skull found at a site in Kenya suggests early humans living in Africa were incredibly diverse. The 22,000-year-old skull is not a new species and is clearly that of an anatomically modern human, but is markedly different from similar finds from Africa and Europe from the same time, the researchers said…. [T]he new findings suggest that during this early period of human history, Africa may have supported even greater human diversity, with small, offshoot lineages that no longer exist today….”
A New Theory on How Neanderthal DNA Spread in Asia – “Researchers have discovered that Neanderthals interbred with the ancestors of Asians at two points in history, giving this population an extra infusion of Neanderthal DNA.”
Division of labor by sex and age in Neandertals: an approach through the study of activity-related dental wear – “The study reveals that all individuals have cultural striations, but those detected on the adult females are longer than the striations found in adult males. Regarding the distribution of dental chipping, the prevalence of this trait is higher in the maxillary dentition of males whereas females have the majority of dental chipping on their mandibular teeth. T he differences detected on the overall activity-related dental wear pattern denote a difference or a division of labor by age and sex in Neandertals while using the mouth as a third hand, i.e., in activities other than the provisioning of food, and provide new evidence for the lifestyle of this Pleistocene fossil human species.” – h/t paleogenomics!
European languages linked to migration from the east – “Large ancient-DNA study uncovers population that moved westwards 4,500 years ago.” — see also Massive Migration and Origins from greg cochran.
A story of 69 ancient Europeans – from dienekes. you need to read this one!
Y chromosomes and Catalan surnames – “‘By genotyping 17 Y-STRs and 68 SNPs in ~2500 male samples that each carried one of the 50 selected Catalan surnames, we could determine sets of descendants of a common ancestor, the population of origin of the common ancestor, and the date when such a common ancestor lived. Haplotype diversity was positively correlated with surname frequency, that is, rarer surnames showed the strongest signals of coancestry. Introgression rates of Y chromosomes into a surname by non-paternity, adoption, and transmission of the maternal surname were estimated at 1.5−2.6% per generation, with some local variation. Average ages for the founders of the surnames were estimated at ~500 years, suggesting a delay between the origin of surnames (twelfth and thirteenth centuries) and the systematization of their paternal transmission. We have found that, in general, a foreign etymology for a surname does not often result in a non-indigenous origin of surname founders; however, bearers of some surnames with an Arabic etymology show an excess of North African haplotypes.'” – @dienekes’.
Stone Age skeleton judged Norway’s oldest – 8000 years old.
Italic “Eteocretan” Sea peoples? – also @dienekes’.
Make Love, Not Disease – “New research on the genetic advantages of sexual reproduction has found that blending our genes through sex helps purge us of disease mutations.”
Gene Changes Make Humans’ Sense of Taste Unique – “Our ability to eat bitter plants help distinguish us from our ancestors and chimpanzees today.”
Elevated germline mutation rate in teenage fathers [pdf] – “We observe, as expected, that the overall mutation rate for fathers is seven times higher than for mothers. Also as expected, mothers have a low and lifelong constant DNA mutation rate. Surprisingly, however, we discover that (i) teenage fathers already set out from a much higher mutation rate than teenage mothers (potentially equivalent to 77–196 male germline cell divisions by puberty); and (ii) ageing men maintain sperm DNA quality similar to that of teenagers….” – h/t andrew sabisky! jayman tweeted: “8.2% false paternity rate in West Africans and 1.3% in Middle Easterners in this sample.”
Escape from crossover interference increases with maternal age – h/t billare! who tweeted: “Higher recombination rates in older women, being less concentrated in the usual hotspots. Men tend to stick w/theirs.”
Predicting and retrodicting intelligence between childhood and old age in the 6-Day Sample of the Scottish Mental Survey 1947 – “Terman–Merrill Stanford–Binet intelligence test scores at age 11 years correlated .72 with verbal intelligence at age 77. Adding another test from age 11 and educational took the multiple R to .81. National Adult Reading Test scores at age 77 and educational had a multiple R of .75 with IQ scores at age 11.” – h/t stuart ritchie! — see also Steady as she goes from dr. james thompson.
Peer effects: they exist but they’re not very big – from ben southwood.
Indian states: G and S factors – from emil kirkegaard.
State IQ estimates (2013) and 2013 IQ estimates by state, total and white only and State IQ estimates, blacks only (2013) and State IQ estimates, Hispanics only (2013) and IQ by race and parental educational attainment – from the awesome epigone.
Nailing liberalism / conservatism by the 50 U.S. States – from bryan pesta.
Low IQ ups risk of heavy drinking among men – “The researchers analysed data collected from 49,321 Swedish males born during 1949 to 1951 and who were conscripted for Swedish military service from 1969 to 1971. IQ results were available from tests performed at conscription, and questionnaires also given at conscription provided data on total alcohol intake (consumed grams of alcohol/week) and pattern of drinking, as well as medical, childhood and adolescent conditions, and tobacco use. Adjustments were made for socio-economic position as a child, psychiatric symptoms and emotional stability and the father’s alcohol habits. ‘We found that lower results on IQ tests in Swedish adolescent men are associated with a higher consumption of alcohol, measured in both terms of total intake and binge drinking,’ Sjolund said.” h/t ruta akula!
Mathematical Proof Is Not Minutiae And Irreducible Complexity Is Not A Theory: A Final Response To Burt And Simons And A Call Tl Criminologists – from brian boutwell et al. brian tweeted: “Our second response to the call within Criminology to ban twin research.”
A two-dimensional model of psychopathy and antisocial behavior: A multi-sample investigation using items from the Psychopathy Checklist-Revised – h/t richard harper! who tweeted: “[P]sychopathy as fearless affect plus disinhibited lifestyle, then plus anti-social to get crime.”
Birds of a “bad” feather flock together: The Dark Triad and mate choice – “[W]omen high in psychopathy considered the Dark Triad traits in potential male partners more physically attractive and desirable for an one-night stand, as well as a potential husband. Men who were high on psychopathy were likewise attracted to psychopathy in potential mothers.”
Cads and dads – “Promiscuity and fidelity seem to be specific biological adaptations. Their manifestations in men and women are not as different as you might expect.” (whatever’s gotten into the economist these days?)
Sex Differences in Preferences for Humor: A Replication, Modification, and Extension [pdf] – “[M]en prefer women who are receptive to their humor whereas women prefer men who produce humor. These findings held even after we modified Bressler et al.’s questionnaire for better conceptual validity. Furthermore, using a separate measure designed to assess trade-offs, we found that men viewed humor receptivity as a necessity and humor production as a luxury when they were asked to create an ideal long-term partner. For women, it was just the opposite.”
The influence of prenatal hormones on occupational choice: 2D:4D evidence from Moscow – “Women in enterprising occupations exhibited lower measured 2D:4D ratios than average. Those in conventional and social work had higher 2D:4D ratios. Results confirm previous findings on 2D:4D and gender-specific occupational interests.”
Examining the Impact of Peer Group Selection on Self-Reported Delinquency: A Consideration of Active Gene–Environment Correlation – h/t jayman! who tweeted: “Do peers still influence adolescent delinquency after taking into account genetic influences? No.”
Socioeconomic status and sick leave granted for mental and somatic disorders: a prospective study of young adult twins – “Low SES is associated with a higher level of sick leave granted for both mental and somatic disorders among young adults, but these associations are confounded by factors that are common to co-twins. Education and income are therefore not likely to strongly affect sick leave in young adulthood.”
List of genetic confounds – from emil kirkegaard.
Sibling differences in low birth weight, dopaminergic polymorphisms, and ADHD symptomatology – “[L]ow birth weight siblings are at significantly greater risk of exhibiting symptoms of ADHD during childhood relative to their normal birth weight siblings. Moreover, possessing greater genetic risk on three dopaminergic genes (DAT1, DRD2, and DRD4) relative to a sibling appears to exacerbate the link between sibling differences in birth weight and sibling differences in ADHD symptomatology.”
What is different about the brains of “SuperAgers” – “Compared with average elderly individuals, they found fewer Alzheimer-type neurofibrillary tangles and an increased packing density of von Economo neurons, especially in the anterior cingulate.”
“Bad genes” & criminal responsibility – MAOA stuff.
What does it say about Owen Jones that he isn’t interested in scientific research? – “What I find irritating about progressive politics is that it ignores and contradicts science, while at the same time pretending to be in favour of reason. The entire worldview is based on the tabula rasa idea of human nature which is contradicted by science. The blank slate makes the progressive goal of equality of outcomes possible; indeed, if equality is not achieved there can only be nefarious forces at work and ‘more work to be done’.” – from ed west. see also Fancy a job in academia or the media? Best brush up on the new political correctness – “[Political correctness is] a faith, and it does not matter how daft the belief systems of a faith appear to a rational mind; if its critics sound backwards and out of touch and rural – literally ‘pagan’ – it will succeed.”
Both liberals and conservatives have anti-science biases, study finds – “New research suggests that liberals, as well as conservatives, can be biased against science that doesn’t align with their political views.” — see also Nuclear Power and the Anti-Science Ideology of the “Progressive” Left from helian.
Why science is so hard to believe – “Science appeals to our rational brain, but our beliefs are motivated largely by emotion, and the biggest motivation is remaining tight with our peers. ‘We’re all in high school. We’ve never left high school,’ says Marcia McNutt. ‘People still have a need to fit in, and that need to fit in is so strong that local values and local opinions are always trumping science. And they will continue to trump science, especially when there is no clear downside to ignoring science.'”
Have Mormons been bred for gullibility? – from agnostic.
Islam Is Not a Religion of the Book – “By this, I mean that as a whole humans are prone to accepting the primary causal role of reflective cognition, of beliefs avowed and rationales offered. We are confident in our conscious self control, despite a robust body of cognitive psychology which implies that much of our cognition is not under the control or constraint of rational faculties. This problem is particularly extreme among intellectuals, the very class which also attempts to understand human phenomena. Through the simple process of introspection and extrapolation intellectuals tend to reduce human action to the outcome of ratiocination, inference from eternal axioms. This is wholly inadequate to a phenomenon as complex as religion.” – from razib.
Your DNA is everywhere. Can the police analyze it? – “Supreme Court weighing if we must live in sealed bubbles to maintain DNA privacy.”
Old India’s Village of Warriors Becomes Birthplace of Bouncers – “Look closely and it becomes clear that the bouncers are all of a single physical type, their chests and biceps built like the front bumper of a sport utility vehicle. If they look like cousins, it is because they are. A startling number of them share a family name, Tanwar, and when the nightclubs close many will return to the same nearby village, a place where women walk down dusty lanes with their faces obscured by a cloth, balancing stacks of dried cow dung on their heads, much as their ancestors did three centuries ago…. The musclemen from the village of Fatehpur Beri are the descendants of the original inhabitants of the city, a genetic line that fortified itself over the course of centuries as they defended their village against waves of invaders on their way to the seat of empire. The sons and grandsons of cow and goat herders, they were born in an outpost surrounded on all sides by croplands. As Fatehpur Beri was swallowed by the expanding city, its spartan strongmen continued to train in the traditional way, stripping down to loincloths and wrestling in a circle of mud. But they were forced to look for a new line of work. ‘There is an element of the warrior in the Tanwars,’ said Ankur Tanwar, who opened the village’s first gym about a decade ago. ‘We fought with the Muslim invaders. We fought with the Britishers.'”
Ancient Egyptians had state-supported health care – at least some of them did.
bonus bonus: The Cold May Have Cost Penguins Most of Their Taste Buds – “Recent genetic analysis shows that penguins can’t taste sweet or bitter, and scientists think sub-zero temps may be to blame.”
bonus bonus bonus: Limpet teeth set new strength record
bonus bonus bonus bonus bonus: Lost Sherlock Holmes story discovered
bonus bonus bonus bonus bonus bonus: a poem. (^_^)
bonus bonus bonus bonus bonus bonus bonus: #TheTitleOfMySexTape (~_^)
(note: comments do not require an email. limpet tooth.)
this is just me cutting-and-pasting a couple of comments from jayman…’cause they’re AWEsome comments! (^_^)
“…just a couple of centuries or so. Is that really enough time to effect that much genetic change according to your theory?”
jayman responded here [bolding by me]…
“One of the simplest models of directional selection, truncation selection, where the bottom (or top) x% for a trait fail to reproduce is easy to model and produces something that closely fits observed situations.
“Say those 1 standard deviation below average for a trait fail to reproduce – roughly the bottom 16%. (In terms of numbers, this isn’t far off from the fraction of people that fail to reproduce in modern America.)
“The breeder’s equation gives us the selective effect:
“[R = h^2 * S]
“R = response to selection (mean of trait in following generation. S = selection differential (mean of trait of parental population). h^2 = additive heritability of trait.
“If we assume those 1 s.d. below average fail to reproduce, then the mean of the parental population (assuming trait in question is normally distributed) is the mean of truncated bell curve cut at -1 s.d. which you can find (with some…fancy math) to be +0.29 sd.
“Since the additive heritability of most traits is 0.5, the response to selection in that case is 0.29 * 0.5 = 0.145 sd/generation. If this were IQ, that would correspond to a ~2.2 point gain per generation. Assuming sustained selection, the population mean would move one whole standard deviation in just 7 generations (or about 200 years)! I mentioned IQ, but this will work just as well for any quantitative trait with a similar additive heritability, including the personality traits associated with a fine manorial serf – which you [could] model collectively as a ‘manorial quotient’ (MQ).“
“The World Values Survey gives us a neat way to quantify overall mean clannishness around the world:
“It’s even mapped in standard deviations.
“Outbreeding has produced an evolutionary shift to the right (maybe to the upper right) for NW Euros on this map. If we assume they started about where the Slavs are now, that means they moved +2 or +3 s.d. over the course of the relevant evolutionary time. Such a change (given the case of strong, sustained directional selection) could take as little as 400-600 years, given the formula above.“
and that, dear readers, is how you make hbd chick smile. (^_^)
edit: oh! jayman promises that there’s gonna be more like this in an upcoming mega-post on his blog, so stay tuned!
(note: comments do not require an email. break open the bubbly!)
just a reminder: davide piffer and jeff hsu are looking for the genomes of clever folks. if you have a high iq, and have made use of 23andMe’s services, they’d like to poke around in your data!:
This research is conducted by Davide Piffer (Italy) and Jeff Hsu (USA)
We seek to identify genes that have an effect on general intelligence in humans. For that reason we need raw genome data from high IQ individuals.
The preliminary phase of our project (analyzing genomes from two scientists) has produced brilliant results and for this reason we want to follow up with genomes from more high IQ individuals.
Many people have already taken the 23andMe test, which enables its users to download raw data file. We’re looking for genomes from individuals whose IQ is at least 2.5 SDs above average.
The results of this study will be published on a pre-print, open access server (e.g. biorXiv, PeerJ) and will be available to everybody, in the true spirit of free science and scientific inquiry. Subsequently we may decide to follow up with a submission to a peer-reviewed scientific journal (e.g. PlosOne, Nature, etc.). Names of participants will not be disclosed (unless expressely requested by you or any other potential participant).
Genome files will be anonymous (a random code will be assigned) and will not be published. Please send genome raw data file (.zip) along with IQ score to: email@example.com
Ancestry information (e.g. nationality and ethnicity) is needed (e.g. White American; Italian; German, etc.) to correctly match genomes to their reference population. If you have any questions, do not hesitate to contact us at the above email address.
Davide Piffer (Italy)
Jeff Hsu (USA)
previously: crowdsourcing hbd (iq) research!