Archives for posts with tag: biology 101

so the mother of all meta-analyses of twin studies and the heritability of human traits was published the other day: “Meta-analysis of the heritability of human traits based on fifty years of twin studies” [pdf].

the authors looked at “17,804 traits from 2,748 publications including 14,558,903 partly dependent twin pairs, virtually all published twin studies of complex traits.” 14.5+ MILLION twin pairs! as james thompson said, this study pretty much represents “the mother of ‘F*** Off’ samples.” (~_^) in future, if someone says to you that twin studies were debunked a long time ago, blah, blah, blah, just point them to this paper.

and the upshot is: we are not blank slates. we never were.

from the paper, “[A]cross all traits the reported heritability is 49%.” in other words, these researchers found that pretty much half of the variance in all sorts of physical and behavioral traits in humans — the differences that we see between people — can be accounted for by genetics.

here’s a key table from the paper. i took the liberty of jiggling it around a bit so it would fit better on the blog (h2 is what you should be looking at here — that’s narrow sense heritabilty):

twin studies meta-analysis

the press has picked this up as there being an even split between nature and nurture, genes versus “the environment.” here, for example, from the huffington post*:

“Nature Or Nurture? The Long-Running Debate May Finally Be Settled”

“It’s an age-old debate: do our genes make us who we are, or is it the environment in which we were raised?

“There’s long been agreement that both ‘nature’ and ‘nurture’ play some role in determining many aspects of our physical and mental selves, from our height and weight to our intelligence and disposition. But as to which plays the bigger role in shaping us, scientists have never seemed to agree.

“That debate may now be over, thanks to a sweeping analysis of studies conducted around the world for more than five decades. The analysis — involving more than 14.5 million twin pairs from 39 countries — indicates that nature and nurture are virtually tied.

“Across all of our traits, in other words, genes and environment exert equal influence.”

yeeeessss…but what is “the environment”? on hearing that most people will think of things like reading bedtime stories to kids or playing mozart to your unborn fetus. but those sorts of things are decidedly not what the environment is in this context. from kevin mitchell of wiring the brain:

i’ve blogged this before, but i think we all need to read it again — from steven pinker on “the environment”:

“Even the technical sense of ‘environment’ used in quantitative behavioral genetics is perversely confusing. Now, there is nothing wrong with partitioning phenotypic variance into components that correlate with genetic variation (heritability) and with variation among families (‘shared environment’). The problem comes from the so-called ‘nonshared’ or ‘unique environmental influences.’ This consists of all the variance that is attributable neither to genetic nor familiar variation. In most studies, it’s calculated as 1 – (heritability + shared environment). Practically, you can think of it as the differences between identical twins who grow up in the same home. They share their genes, parents, older and younger siblings, home, school, peers, and neighborhood. So what could make them different? Under the assumption that behavior is a product of genes plus environment, it must be something in the environment of one that is not in the environment of the other.

But this category really should be called ‘miscellaneous/unknown,’ because it has nothing necessarily to do with any measurable aspect of the environment, such as one sibling getting the top bunk bed and the other the bottom, or a parent unpredictably favoring one child, or one sibling getting chased by a dog, coming down with a virus, or being favored by a teacher. These influences are purely conjectural, and studies looking for them have failed to find them. The alternative is that this component actually consists of the effects of chance – new mutations, quirky prenatal effects, noise in brain development, and events in life with unpredictable effects.

“Stochastic effects in development are increasingly being recognized by epidemiologists, frustrated by such recalcitrant phenomena such as nonagenarian pack-a-day smokers and identical twins discordant for schizophrenia, homosexuality, and disease outcomes. They are increasingly forced to acknowledge that God plays dice with our traits. Developmental biologists have come to similar conclusions. The bad habit of assuming that anything not classically genetic must be ‘environmental’ has blinkered behavioral geneticists (and those who interpret their findings) into the fool’s errand of looking for environmental effects for what may be randomness in developmental processes.”

and more from kevin mitchell:

“Just because some trait is not genetic does not mean it is not innate. If we are talking about how the brain gets wired, any number of prenatal environmental factors are known to have large effects. More interestingly, however, and probably a greater source of variance across the population, is intrinsic developmental variation. Wiring the brain is a highly complex procedure, reliant on cellular processes that are, in engineering terms, inherently ‘noisy’. Running the programme from the same starting point (a specific genotype) does not generate exactly the same output (the phenotype) every time. The effects of this noise are readily apparent at the anatomical level, when examining the impact of specific mutations, for example. In many cases, the phenotypic consequences are quite variable between genetically identical organisms, or even on two sides of the same brain. (If you want to see direct evidence of such developmental variation, take a directly face-on photograph of yourself, cut it in half and make mirror-image copies of the left and right sides. You will be amazed how different the two resultant faces are).

If the way the brain is wired is determined, not just by the starting genotype, but, to a large extent by chance events during development, then it is reasonable to expect this variation to be manifest in many psychological traits. Such traits may thus be far more innate than behavioural genetics studies alone would suggest.

in other words, it’s NOT genes + environment (or nature + nurture) — not as most people would think of it anyway. it’s genes + shared environment (which, since it’s shared, i.e. the same for the individuals in question, oughtn’t to make a difference, right?) + nonshared environment (which can include de novo mutations and development noise, which also may be heritable! iow, variation itself might be a genetic trait.). not much room for the effects of nurture here.

so, when you see a figure like 51% for “environmental” causes behind the differences we see in traits between people, remember that that very much includes biological causes like new mutations that are particular to individuals and developmental “noise,” which again may ultimately be regulated by genes.

(and, no, it’s not epigenetics either! see here and here and here.)

h/t once again to jayman for cluing me in on this in the first place! (^_^)
_____

*to give credit where credit is due, the huff post journalist did mention that part of what’s included in “the environment” is measurement error. that is correct. edit: see comment below about measurement error. so the 49% heritabilty figure should be considered a very conservative figure.

p.s. – there’s even a dedicated website where you can have a look at all the heritability numbers for yourself. enjoy!

see also: Gone with the Wind from dr. james thompson, Nature, nurture and noise from kevin mitchell, and About Developmental Noise and Environmental Hereditarianism from jayman.

previously: it’s not nature and nurture…

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via everyone on twitter today:

“ISIS fighters complain they are not being chosen to blow themselves up on suicide missions because leaders’ friends and family get put to the top of the waiting list”

“- Chechen militant angry that Saudis are snubbing them for bombing runs
– Jihadi complains that they are ‘letting their relatives go to front of the line’
– Said ISIS leader Bakr al-Baghdadi’s brother had carried out suicide attack

“Islamic State fighters claim they are not getting the chance to blow themselves up because they are being bumped down the suicide-bomber waiting list by nepotistic leaders.

“A Chechen militant has complained that Saudi jihadis are favouring their own friends and family for bombing missions.

“Kamil Abu Sultan ad-Daghestani said fighters were becoming increasingly angry after being left languishing on the waiting list for months.

“Ironically, he said some militants were dying on the battlefield before getting the chance to carry out a bombing.

“Abu Sultan’s complaint, was posted on a new website named Qonah which is said to be linked to a group connected with Akhmed Chatayev (Akhmad al-Shishani), a Chechen militant in charge of the Yarmouk Battalion of ISIS.

“‘Amir [Leader] Akhmed al-Shishani told me about a young lad who went to Iraq for a suicide mission and he went there because in Sham [Syria] there is a veeeeery long queue [of several thousand people],’ he wrote.

“He said the fighter eventually gave up after three months and returned to Syria, it was reported by Radio Free Europe Radio Liberty.

“The young militant complained that he would only be able to secure a bombing mission through a ‘blat’ with the Saudi leaders – a Russian slang term meaning connections.

“Abu Sultan wrote that the boy said: ‘Those Saudis have got things sewn up, they won’t let anyone in, they are letting their relatives go to the front of the line using blat.’

“He said the only to deal with the ‘corruption’ was to make a direct appeal to ISIS leader Abu Bakr al-Baghdadi.

“He recently noted on another site that Baghdadi’s own brother and the son of his second-in-command had carried out suicide bombings.

“The leader’s cousin also reportedly blew himself up at a checkpoint in Iraq in April….”

heh! (~_^)

see also A Boratesque story from ISIS-land: Chechen ISIS fighters being cheated out of paradise by Saudi nepotism from ed west.

btw, buy ed’s latest kindle single!: 1215 and All That: A very, very short history of Magna Carta and King John (and @amazon.co.uk).

(note: comments do not require an email. the people’s front.)

you will never understand human biodiversity without first turning an hbd-eye on yourself.

before i elaborate on that, a small exercise. indulge me.

at the end of this sentence, when i ask you to, i want you to raise your eyes from your monitor (or smartphone or tablet or whatever device you’re using), glance around for a few seconds, and then come back here. okay: go!

back? great.

now, i don’t know exactly what you saw during your brief adventure away, but what i do know is that when you looked around your room or office or the coffee shop or your own private tropical island (d*mn you!), you experienced seeing a smooth, undisturbed, flowing picture of your surroundings — it was a video-like experience (hopefully not a shaky cam-like one! if so, get to a doctor, quick!). that experience is a false one, created by your brain to make life easier for you. what happens, in fact, is that each and every time we move our gaze from one object or scene to another, in the intervening nanoseconds, we are effectively blind. we don’t “see” anything for those split seconds. the reason we don’t experience what would presumably be a very disturbing and confusing one — the lights going off and on all day long! — is because our brains fool us. the brain interpolates the visual data captured via eyeballs, etc., and presents it all to its owner (user?) in a nice, even — but unreal — picture of what that individual “sees.”

cool, huh? yeah.

the reason i bring this up is just to illustrate how our brains are not really to be trusted. fantastic, wonderful, unfathomable organ! — but one that fools us. a lot! it deceives us so that we don’t go around bumping into things all day long (the saccadic masking mentioned above). it deceives us (deceives itself!) so that we can decieve others. it probably fools each of us into believing that we are discrete individuals — that we are or have “selves.” h*ck! it even looks like our consciousness is not a stream but more like rhythmic pulses. all for good evolutionary reasons, of course. but, still, there it is: the brain is a trickster.

once you realize this about the human brain — that it’s an indispensible but untrustworthy organ — all of the cognitive biases and dissonances that we suffer from start to make sense. humans are not rational creatures. we are capable of some amount of logic and rational thought (some more than others), but more often than not, our “reason” serves as an excuse generator for our innate drives, desires, and proclivities.

the next thing you need to know — and you really have to internalize this — is that all of those drives and desires and proclivities are innate. all behavioral traits are heritable to some degree or another, which means that genes are behind them, and which means that there’s not much any of us can do to change our natures. for instance, there prolly aren’t specific genes that will make a person a christian versus a muslim, but there are definitely genes “for” religiosity. which religion a person with “genes for” religious belief follows will obviously depend to a large degree on the culture in which he is immersed, but persons with “genes for” religious belief will tend to be religious or spiritual somehow.

all behavioral traits are heritable. and, so, you cannot change people or peoples — not fundamentally. people are what they are. you are what you are, and so most of your thoughts and conclusions and feelings about life and the world around you are expressions of your innate traits. mine, too. (don’t worry. i’ll get to that.) and let’s be honest: innate traits and a deceiving brain are no foundations for uncovering the truth. we cannot rely on our gut instincts in trying to uncover the facts about reality or to (consciously) understand how the world works. the only way around this problem of our lyin’, cheatin’, no-good brains is to rely on science and its finding. of course, since science is conducted by humans, we run into all those cognitive biases, etc., again. but with enough effort, i think we can eventually discover some truths. either that or space stations will some day start falling out of the sky, and we’ll know we’re doing it wrong.

now back to my initial point: you will never understand human biodiversity without first turning an hbd-eye on yourself. first, learn this about yourself — that your thoughts and feeling and behaviors are heritable and largely out of your control — and then try to apply this knowledge to your understanding of other individuals and groups. examine your ideas and your feelings. your gut instincts (be especially suspicious of those!). your beliefs. you may think you have thought through the important questions rationally, but chances are you haven’t. not really. be honest with yourself. and be hard on yourself. but remember to have a laugh about it all, too — how absurd it all is really at the end of the day! (~_^)

remember my three laws of human biodiversity. and don’t ever forget that there are exceptions to the rules — and that you might be one of them — or your neighbor might. always — always! — keep in the forefront of your mind the concept of AVERAGE when you think about the human biodiversity between groups — and that not every member of a group will fit the average. do NOT pick and choose the areas of human biodiversity that suit your tastes and disregard the rest. you won’t get any dessert if you do.

most importantly — and i can’t emphasize this enough — do NOT project your innate feeling and thoughts and inclinations onto others! you might think and feel one way, but the other person sitting next to you might not. and he might really think and feel very differently from you, and have a completely different perspective on the world — different in a fundamental way — that neither he nor you can change, because he was born this way. (or maybe experienced a developmental insult that affected his biology in a similarly permanent sort of fashion.)

do not project your preferences onto other individuals or groups. just because you like to keep a super tidy house (you ocd person) doesn’t mean others do. and just because you and your people feel that living in nuclear families and having loose (or nonexistent) extended family ties is a nice way to live doesn’t mean that other peoples want that. and just because democracy happens to work well in your population — or autocracy, depending on where you’re from — doesn’t mean either of them would transfer well to other populations having different average innate characteristics from your own.

so, below are some aspects of human biodiversity you might want to run through when you’re getting to know thyself. there’s lots more. these are just some things i thought of off the top of my head. (if i were really organized, which i am not, i would’ve linked to how heritable each of these different traits is. maybe i’ll go back and fill those in one of these days. for now, you’re on your own — google ’em. or check jayman’s blog. he’s probably got a lot of the heritability figures over there! (^_^) ) try and see if identifying and recognizing any or all of your innate traits helps you to understand why you think and feel and behave in the ways that you do.

i’ll start.

– are you male or female? men and women on average think and feel differently about an awful lot of things. don’t blame me. i’m just the messenger.

– are you heterosexual or homosexual? or some other sort of sexual? heterosexual men and women on average think and feel differently about quite a lot of things compared to gay men and lesbian women et al. and i don’t just mean about preferred sexual partners. remember that there are always exceptions to these rules. and remember not to PROJECT your thinking/feelings onto other subgroups here (yes, i am looking at you butch lesbian feminists!).

– what is your racial and, to my mind more interesting and important, ethnic background? what other sort of population or subpopulation might you belong to (eg. siberian peoples or sicilians)? are you a person of mixed heritage? plenty of average differences in all sorts of directions here.

– how intelligent are you? what’s your iq? try to remember that people of much lower intelligence than you will have a very hard time understanding a lot of the things that you do, and that you will find it difficult, if not impossible, to grasp the ideas and concepts that people more intelligent than you can. be humble (if you’re able).

– what personality traits characterize you? both big 5 and hexaco. are you open to experiences? people who score low on openness are generally conservative. are you conscientious? in other words, are you efficient and organized or more easy going and (*ahem*) disorderly? are you an extravert or an introvert? if you’re an extravert, you’re probably not enjoying this exercise at all. sorry. (in my experience, extraverts are not very introspective.) are you agreeable? kind, sympathetic, warm. or are you angry all the time? are you neurotic or emotional? or are you more stable? and from the hexaco scale, where do you rank when it comes to honesty-humility?

– how old are you? if you’re under, say, 24, keep in mind that your brain hasn’t finished developing yet. your frontal lobes are incomplete, so you’ve got very little sense. (~_^) if you’re a young male, between say 16 and 24, you might be quite aggressive (although not necessarily violent) and risk tasking. be careful out there! if you’re (*ahem*) older, remember that everything slows down with age. (sorry to remind you of that!) it does get harder to teach old dogs new tricks. and everybody, remember that, in general, each of us becomes more like our true selves as we get older, because we get to choose our preferred environments once we grow up.

– are you religious or areligious — or even irreligious? remember that religiosity/spirituality is highly heritable.

– are you conservative or liberal or something in between? or something more extreme? or apolitical? remember than political orientation is also highly heritable.

– are you an optimist or a pessimist? is the glass half full or half empty? are you a depressive, emo kid or are you one of those always-chipper people? again, all highly heritable.

– are you a follower or a contrarian? i haven’t seen much research on this (i know there is some, but i wish there was more), but i’d bet a ton of $$$ that these traits are highly heritable, too. prolly tie in with all the personality traits above.

– are you on the autism spectrum somewhere? one of simon baron-cohen’s systemizers or empathizers? do you have adhd? ocd? a touch of paranoid schizophrenia? (just because you’re paranoid….) all of these conditions can — and do! — obviously strongly affect the way individuals think and feel about the world around them.

– what about your personality and the dark triad? are you a psychopath? narcissist? machiavellian in your nature? again, all of these relate back to the personality traits above. are you histrionic?

– what’s your 2d:4d ratio? no one’s sure what’s behind the differences of these, but the ratio does correlate with all sorts of traits and behaviors.

– are you from what i call a “clannish” population or not? from a population that historically was located behind the hajnal line or not? you may disagree with me on why i think “clannishness” exists as a set of behavioral traits in different populations, but there’s not much disagreement on the fact that the behaviors do exist (and are measurable): individualism/collectivism vs. familism/non-collectivism; universalism vs. particularism; civic-minded/commonweal oriented vs. not civic-minded/not commonweal oriented; low corruption vs. high corruption; etc. again, you might be an exception to your population’s rule. then again, you may not be.

– do you think like a westerner?

– and, a special shout-out to one super-group: are you eastern european? if so, you might prefer authoritarianism (especially left-wing authoritarianism). keep in mind that others of us don’t.

that’s it! that’s all i’ve got for now. (^_^)

see also: me, myself, and i

previously: what is human biodiversity (hbd)? and hbd chick’s three laws of human biodiversity and you and me and hbd

(note: comments do not require an email. know thyself.)

have you experienced people telling you that you have very pronounced brow ridges? had your dna genotyped (like by 23andMe, for instance)? then glenn geher and pals at SUNY would like you to take their personality test!:

New Paltz Neandertal Project

We are a research team from the Psychology Department of SUNY New Paltz conducting a research study examining the relationship between genotype and behavior. We are recruiting participants who are at least 18 years old, fluent in English, and who have had their DNA sequenced by a genomics company to complete a short survey (approx. 45 minutes).

the idea is to find out if any particular personality/behavioral traits correlate with neanderthal alleles.

don’t be such a knuckle-walker! go on and take the test! it’s for science. (^_^)

neanderthal

(note: comments do not require an email. i’m a bit of a neanderthal!)

on christ’s arrest in the garden of gethsemane from the gospel of luke 22:39-51 (the revised standard version):

“Jesus went, as was his custom, to the Mount of Olives; and the disciples followed him. And when he came to the place, he said to them, ‘Pray that you may not enter into temptation.’ And he withdrew from them about a stone’s throw, and knelt down and prayed…. And when he rose from prayer, he came to the disciples and found them sleeping for sorrow, and he said to them, ‘Why do you sleep? Rise and pray that you may not enter into temptation.’ While he was still speaking, there came a crowd, and the man called Judas, one of the twelve, was leading them. He drew near to Jesus to kiss him, but Jesus said to him, ‘Judas, would you betray the Son of Man with a kiss?’ And when those who were about him saw what would follow, they said, ‘Lord, shall we strike with the sword?’ And one of them struck the slave of the high priest and cut off his [right] ear. But Jesus said: ‘No more of this!’ And he touched his ear and healed him.”

and the same (sorta!) story from the heliand, an old saxon poem from the early 800s commissioned to aid in the conversion of the saxons on the continent to christianity (“Song 57: Christ’s Deep Fear Before Battle, His Last Salute in the Garden” and “Song 58: Christ the Cheiftain is Captured, Peter the Mighty Swordsman Defends Him Boldly”):

“Christ’s warrior companions saw warriors coming up the mountain making a great din, angry armed men. Judas the hate-filled man was showing them the way. The enemy clan, the Jews, were marching behind. The warriors marched forward, the grim Jewish army, until they had come to Christ. There he stood, the famous chieftain. Christ’s followers, wisemen deeply distressed by this hostile action, held their position in front. They spoke to their chieftain: ‘My lord chieftain’ they said, ‘if it should now be your will that we be impaled here on their spearpoints, wounded by their weapons, then nothing would be so good to us as to die here, pale from mortal wounds, for our chieftain.’ Then Simon Peter, the mighty, the noble swordman, flew into a rage. His mind was in such turmoil that he could not speak a single word. His heart became intensely bitter because they wanted to tie up his lord there. So he strode over angrily, that very daring thegn, to stand in front of his commander, right in front of his lord. No doubting in his mind, no fearful hesitation in his chest, he drew his blade and struck straight ahead at the first man of the enemy with all the strength in his hands, so that Malcous was cut and wounded on the right side by the sword. His ear was chopped off. He was so badly wounded in the head that his cheek and ear burst open with the mortal wound. Blood gushed out, pouring from the wound. The men stood back. They were afraid of the slash of the sword.”

(~_^)

pre-christian germanics were clannish. very clannish!

presumably, this is the sort of thing discussed by james russell in his The Germanization of Early Medieval Christianity, another book which i haven’t read.

here’s jesus the warrior for you, from the stuttgart psalter, also from the early 800s:

Stuttgart_Psalter_fol23

btw, i transcribed those passages from lecture 15 of the Early Middle Ages audio course from The Great Courses. excellent course!

(note: comments do not require an email. jedi jesus.)

william hamilton, considered to be one of the — if not the — greatest evolutionary theorists since darwin, had this to say:

“The incursions of barbaric pastoralists seem to do civilizations less harm in the long run than one might expect. Indeed, two dark ages and renaissances in Europe suggest a recurring pattern in which a renaissance follows an incursion by about 800 years. It may even be suggested that certain genes or traditions of pastoralists revitalize the conquered people with an ingredient of progress which tends to die out in a large panmictic population for the reasons already discussed. I have in mind altruism itself, or the part of the altruism which is perhaps better described as self-sacrificial daring. By the time of the renaissance it may be that the mixing of genes and cultures (or of cultures alone if these are the only vehicles, which I doubt) has continued long enough to bring the old mercantile thoughtfulness and the infused daring into conjunction in a few individuals who then find courage for all kinds of inventive innovation against the resistance of established thought and practice. Often, however, the cost in fitness of such altruism and sublimated pugnacity to the individuals concerned is by no means metaphorical, and the benefits to fitness, such as they are, go to a mass of individuals whose genetic correlation with the innovator must be slight indeed. Thus civilization probably slowly reduces its altruism of all kinds, including the kinds needed for cultural creativity (see also Eshel 1972).”

so hamilton clearly thought that biology and human biodiversity strongly influence culture and history, including the broad movements of history like renaissances or maybe even reformations or enlightenments, etc. and he thought that outbreeding, specifically too much outbreeding (i.e. panmictic populations), and presumably inbreeding too, relate to the selection for altruistic behaviors…and, therefore, certain aspects of cultures and history, etc. (remember that there’s more to hbd than just iq. (~_^) ) i dunno, maybe i and other hbd-ers are crazy (if so, we’re in GOOD company!), but this just makes intuitive sense to me. as john derbyshire said [15:00]:

“…if dimensions of the individual human personality are heritable, then society is just a vector sum of a lot of individual personalities.”

i like the big, probably impossible to answer fully questions: where does culture come from? where do institutions come from? where do renaissances come from? i don’t have the answers to those questions. nor am i under any illusions that i’ll ever be able to answer them. but am i very certain that they cannot be answered without taking into consideration human biology and biodiversity along with more conventional explanations drawn from history, economics, etc., and so i like to periodically bring them up.

so, if you happen to be new here, if you don’t like questioning — on every level — or biological explanations applied to The Big Questions, i’m afraid you’ve come to the wrong place. sorry. for my fellow hbd-ers — see you back here later in the week! (^_^)

previously: renaissances
_____

p.s. – btw, my vacation has been extended by a week (long story), so i’ll be back properly next week. sorry for the delay! (*^_^*)

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there’s been a theory floated for a few years now that there was a sort of apartheid system in early anglo-saxon england in which the angles and saxons and jutes didn’t really mix with the native britons. or vice versa. from thomas, stumpf, and härke:

“Reproductive isolation and differential social status along ethnic lines is a frequent, temporary consequence of conquest and settlement, the best-known modern case being the Apartheid system in South Africa. In the post-Roman period, intermarriage between dominant immigrants and subject natives was banned in Visigothic France and Spain in the late fifth and early sixth century (King 1972). The Normans in eleventh- and twelfth-century England operated a conquest society in which the native English and Welsh had a lower legal status than Normans (Garnett 1985), and intermarriage, where it happened, was predominantly unidirectional, i.e. Norman men marrying English women. In Anglo-Saxon England, elements of an apartheid-like society can also be perceived in a Wessex law code of the seventh century which distinguishes clearly between Saxons and ‘Welsh’ (Britons) and gives the former a significantly higher legal status, some two centuries after the initial immigration (Whitelock 1979). Archaeological and skeletal data (Härke 1990, 1992), as well as textual evidence (Woolf, 2004), have been used to suggest a situation of limited intermarriage between immigrant Anglo-Saxons and native Britons until the seventh century when this distinction began to break down.”

for more on this theory, see: Anglo-Saxon immigration and ethnogenesis.

now it seems as though the recently published genetic study by leslie et al. may back up this idea. from the Supplementary Information [pdf – pg. 18]:

The Cent./S England inferred admixture date is older, at around 1200 years ago. This is moderately, but significantly, more recent than the historically accepted time of approximately 1400 years ago (around 600) for the Anglo-Saxon migration into England. This discrepancy is unlikely to be explained by errors in our human generation time (we used 28 years) because an unlikely generation time of 33 years or higher would be required to account for this difference. Instead, an important point is that the date of admixture cannot be earlier than the arrival of a group, but can be later if mixing did not occur for some period (e.g. if the Anglo-Saxon community remained distinct for some period after arrival), or if mixing took place gradually, and initially at a relatively slow rate.”

so, they’re saying that intermarriages between the anglo-saxons and the native britons didn’t really get going until the 800s.

both the anglo-saxons and probably the native britons (presuming they were rather like the native irish and scots), like every other pre-christian northern european group, married their cousins to some degree or another. we know for certain that the anglo-saxons did, because augustine of canterbury wrote several frantic letters to pope gregory the great about the problem (he viewed this as a problem since already by this point in the 600s the church had banned marriages to close cousins).

across the channel in the frankish kingdoms, cousin marriage didn’t became socially unacceptable until the 800s, even though there were local bans issued by bishops in the frankish kingdoms as early as the 500s. as i wrote in a previous post:

from “An Unsolved Riddle: Early Medieval Incest Legislation” in Franks and Alamanni in the Merovingian Period: An Ethnographic Perspective (1998), a collection of papers from an “historical archaeoethnological” conference [pgs. 109-110]:

“In the course of the eighth century the Frankish campaign against incest gained momentum, aided by papal decrees and letters which began to circulate in the North (De Jong 1989:38-41). When it came to blood relations papal guidelines were more radical than Frankish episcopal and royal decrees, but in other respects — such as spiritual kinship — Rome and the Frankish leadership saw eye to eye right from the beginning. Letters sent from Rome to Boniface reveal an increasingly rigid papal position. Gregory II forbade all unions between blood relations and affinal kin (‘*quamdiu se agnoscunt affinitate propinquos*’), but permitted the recently converted a marriage ‘*post quartam generationem*'; his successor Gregory III withdrew any such privilege, assuring Boniface that marriage within the seventh *generatio* was out of the question….

“In practice…it did not make any difference whether one forbade marriage ‘until the seventh *generatio*’ (Gregory III), or proclaimed an unspecified ban on all kinswomen and affines (Gregory II). Both meant the same: marriage and kindred did not go together. Pope Zachary expressed this clearly in 743, stating that no Christians were permitted to marry if they were in any way related to each other (Werminghoff 1904:19-21). Avoidance of kin-marriage had become one of the defining criteria of Christianity….”

by the 800s [pg. 120]:

By the ninth century, a marriage in the third *generatio* [i.e. second cousins – h.chick] had become scandalous, but the fourth generation remained a viable option, along with a whole range of more distant kin (Le Jan 1995:316-17). This pattern persisted well into the tenth and eleventh centuries.”

i’m not one hundred percent certain, but i think that this shift to the regular avoidance of cousin marriage by the franks probably had something to do with the establishment of parish churches in the 700 and 800s by pepin the short and charlemagne. once there was “a church in every village,” the message that cousin marriage was not permitted would’ve been more readily heard, and, perhaps, more easily enforced (by the local priest).

i don’t know anything about the establishment of parishes in england (yet), but perhaps the english — the anglo-saxons and britons — were on a similar trajectory as the franks with regard to cousin marriage. perhaps they, too, didn’t really start to take the bans seriously until sometime in the 800s, despite there having been some very early laws forbidding cousin marriage in some of the anglo-saxon kingdoms (like in the late 600s in kent). if there was such a delay in avoiding cousin marriage in england in the seventh and eighth centuries, then there wouldn’t have been much intermarriage between the anglo-saxons and britons during those centuries simply because they all would’ve been still mostly marrying their own cousins or other close kin (i.e. fellow clan or kindred members). if so, then genetic exchange between the groups would’ve become much more likely once cousin marriage began to be consistently avoided. maybe it took the church and its bans on cousin marriage to end anglo-saxon apartheid.

just a thought. Further Research is RequiredTM. (^_^)

previously: free cornwall now! and anglo-saxon mating patterns

(note: comments do not require an email. anglo-saxon rings.)

here’s a map (on the left) of anglo-saxon burial sites of the 5th to 7th centuries from “Anglo-Saxon immigration and ethnogenesis” compared to the distribution of the eastern, central, and southern english genetic cluster (red squares on map to right) from leslie et al. who found between 10-40% of the ancestry of those english to be anglo-saxon:

harcke - anglo-saxon burial sites 5th to 7th-8th centuries

that is all! (^_^)

previously: free cornwall now!

(note: comments do not require an email. anglo-saxon burial: lady and her cow.)

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