linkfest – 10/19/15

First humans to leave Africa went to China, not Europe“The first humans to leave Africa decamped to far east Asia, not Europe. A trove of ancient teeth found in a cave in China adds evidence to the idea that humans reached the region thousands of years before they made it to Europe. The find suggests that modern humans reached China between 80,000 and 120,000 years ago. That challenges the widespread assumption that humans didn’t leave Africa until 60,000 years ago. It’s further evidence that Homo sapiens may have left Africa several times, says María Martinón-Torres of University College London. ‘It means we have to re-think different models of our dispersal.'” – and john hawks tweeted: “An 80kya modern human population in SE Asia w/Denisovan ancestry might help explain pattern of admixture in Philippines Mamanwa.”

Way Down South“I hear (tweets by Razib Khan, concerning Sankararaman’s talk at ASHG) that the Denisovans had substantially more genetic diversity than Neanderthals (determined mainly by the variety seen in admixed segments)….” – from greg cochran.

Lactase persistence and ancient DNA“‘…it seems plausible to me that the [European LP] allele first appeared in Central Europe, was spread around Europe by the LBK, before being introduced to the steppe later by migration from Europe.'”

Stonehenge builders had barbecue feasts at nearby party centre – and milk and cheeeeeese!

Basques are not simply a fusion of Iberian hunter-gatherers and early farmers“[T]he story told by the PCA is that Basques are the progeny of Bronze Age Iberians, who, unlike their Copper Age predecessors, experienced a pulse of steppe-related admixture from the east…. The key question now is who brought the steppe-related ancestry to Basque country. Were they Indo-Europeans or speakers of Proto-Basque?”

Sex‐specific demography and generalization of the Trivers–Willard theory – h/t owen jones! who tweeted: “Can mothers adaptively adjust offspring sex ratio? It’s complicated….”

The Great Migration and African-American genomic diversity“We find higher African ancestry in southern United States compared to the North and West. We show that relatedness patterns track north- and west-bound routes followed during the Great Migration, suggesting that admixture occurred predominantly in the South prior to the Civil War and that ancestry-biased migration is responsible for regional differences in ancestry. Rare genetic traits among African-Americans can therefore be shared over long geographic distances along the Great Migration routes, yet their distribution over short distances remains highly structured.”

Connectivity matrix predicts fluid intelligence“The enchanted loom is slowly giving up its secrets, of which it holds many. The patterns of brain activity that so many researchers have tracked with wonder are beginning to reveal a larger pattern: the possibility that each of us has a habitual pattern of brain activity which identifies us, and distinguishes us from others. So, dear reader, we are separated by the idiosyncratic rhythms of our brains, dancing to a different beat, visiting a different pattern of cortical locations, and no doubt coming to different conclusions…. The unexpected finding which I find startling is that individuals can be identified by their habitual brain patterns (not just on specific tasks) and those patterns of activity predict fluid intelligence on Raven’s Matrices at about r=0.5.” – from dr. james thompson.

Meta-analysis of associations between human brain volume and intelligence differences: How strong are they and what do they mean?“Positive associations between human intelligence and brain size have been suspected for more than 150 years…. Our results showed significant positive associations of brain volume and IQ (r = .24, R2 = .06) that generalize over age (children vs. adults), IQ domain (full-scale, performance, and verbal IQ), and sex…. We show that the strength of the positive association of brain volume and IQ has been overestimated in the literature, but remains robust even when accounting for different types of dissemination bias, although reported effects have been declining over time.”

Correlation not Causation: The Relationship between Personality Traits and Political Ideologies“Here we test the causal relationship between personality traits and political attitudes using a direction of causation structural model on a genetically informative sample. The results suggest that personality traits do not cause people to develop political attitudes; rather the correlation between the two is a function of an innate common underlying genetic factor.” – h/t robin hanson!

Generalised Anxiety Disorder – A Twin Study of Genetic Architecture, Genome-Wide Association and Differential Gene Expression“A heritability analysis of the same cohort also confirmed a significant genetic component with h2 of 0.42.” – h/t siberian fox! – and jayman tweeted: “I suspect anxiety is more common in some places than others. Perhaps due to genetic pacification.”

A Unified Crime Theory: The Evolutionary Taxonomy“Drawing on a variety of influences, we argue that many types of crime can be understood in the evolutionary context of human life history. Along these lines, we present a framework capable of explaining different patterns of criminal offending both at the individual level as well as the macro-level.” – from brian boutwell et al.

Resting heart rate and antisocial behavior: An updated systematic review and meta-analysis“Low resting heart rate was associated with higher levels of antisocial behavior…. Results were similar across behaviors, including aggression and violence.” – h/t anthony hoskin!

The association between childhood autistic traits and adolescent psychotic experiences is explained by general neuropsychiatric problems – from amir sariaslan et al. amir tweeted: “The ‘p factor’ explains assoc’s btwn childhood autistic traits and adolescent psychotic experiences.”

The Flynn Effect: IQ Testing Across Space and Time – from steve sailer.

What Extroverts and Introverts Can Learn From Snails“Genes may change a snail’s ‘personality’ and the thickness of its skin (or rather, its shell)”

Dimensional assessment of normal and abnormal personality in adults of the general population: Comparison of ‘five’ and ‘alternative five’ personality models – h/t andrew sabisky! who tweeted: “are normal and pathological personality all part of one continuum?”

So what if grammars don’t help social mobility?“On the Today programme and the New Statesman website, a statistic was quoted showing that grammar schools have a smaller percentage of pupils on free school meals than comprehensives. There are probably many reasons for this, but most likely the largest factor involved is that intelligence is hereditary and social class correlates with IQ; in other words, middle-class kids tend on average to be more intelligent than working-class ones. You could make the system fairer by replacing grammar entrance exams (for which richer parents hire tutors to help their children pass) with straight-up IQ tests, but the number of poorer children would still be disproportionately low. In fact the more social mobility we have over the generations, as everyone seems to want, the more that social class will correlate with intelligence. Richard Herrnstein pointed this out more than four decades ago. Many years earlier, Michael Young warned about this very process in The Rise of the Meritocracy. Social mobility does have its downsides; that’s because intelligence is just another privilege you inherit from mummy and daddy.” – from ed west.

The economic value of Breaking Bad: How misbehavior in school pays off for some kids“Surprisingly, we find evidence that some non-cognitive skills that manifest as childhood misbehavior in the classroom (and are predictive of lower schooling attainment) are also predictive of higher earnings later in life.”

A social science without sacred values“We argue (1) that many social scientists are paranoid egalitarian meliorists; (2) that they are therefore very sensitive to threats to a sacred egalitarian narrative; (3) that this sensitivity may be excessive (at least in the domain of science) and may cause researchers to unfairly reject research that challenges egalitarianism; (4) that this may then lead to the marginalization of individuals who forward controversial theories and/or data; and (5) that these tendencies lead to bias in the social sciences.” – from the winegard bros.

Social Status: Down the Rabbit Hole – h/t billare! who tweeted: “There are two systems of social status: Dominance & Prestige. For what selfish reasons might the latter one evolve?” – this was a really interesting read, btw.

Why Drunk Vegetarians Eat Meat – h/t jonathan haidt! who tweeted: “…esp. health vegs; moral vegs feel more disgust.”

Shame, guilt, and facial emotion processing: initial evidence for a positive relationship between guilt-proneness and facial emotion recognition ability“Guilt-prone people are highly skilled at recognising other people’s emotions.” [via] – w.e.i.r.d. study. pretty small n.

Gamblers, Scientists and the Mysterious Hot Hand“We’re all in the same boat. We evolved with this uncanny ability to find patterns. The difficulty lies in separating what really exists from what is only in our minds.” – h/t claire lehmann!

Dobzhansky and Montagu’s Debate on Race: The Aftermath

The Mutant Genes Behind the Black Death“Only a few genetic changes were enough to turn an ordinary stomach bug into the bacteria responsible for the plague.”

The End of Indian Summer“At first, human rights commissions fought discrimination only in employment and housing, and there was strong resistance to prosecution of people simply for their ideas. This situation changed from the 1970s onward. Human rights took the place in society that formerly belonged to religion, and human rights advocates acquired the immunity from criticism that formerly belonged to the clergy. Discrimination was no longer wrong in certain cases and under certain circumstances. It became evil, and people who condoned it in any form and for any reason were likewise evil.” – from peter frost.

Is Eastern Europe Any More Xenophobic Than Western Europe? – yes. but france is an exception in the west.

bonus: superforecasting conference on october 24th, if you happen to be in or near london: Superforecasting and Geopolitical Intelligence- Who can Predict the Future, and how?

bonus bonus: Did photosynthesis begin 3.2 billion years ago?“Rusty rocks from ancient ocean suggest bacteria produced oxygen far earlier than thought.”

bonus bonus bonus: The Beetle That Eavesdrops on an Ant’s Secret Language“A beetle evolves to ‘listen in’ on ants’ chemical messages to one another, changing the balance of an ecosystem.” [via]

bonus bonus bonus bonus: Ants con others into being their slaves by mimicking their scent

bonus bonus bonus bonus bonus: Sticky situation: maple syrup bandits face Quebec courts for infamous heist“Trials are under way for the 2012 attempt to steal $18m worth of Quebec’s sweetest export – a case that has succeeded in capturing Hollywood’s attention.”

bonus bonus bonus bonus bonus bonus: Pop Culture Pulsar: The Science Behind Joy Division’s Unknown Pleasures Album Cover

and the tweet of the week… (^_^)

https://twitter.com/SadHappyAmazing/status/655381841529012224

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

more roh

in “Genomic Runs of Homozygosity Record Population History and Consanguinity” that i posted about yesterday, kirin, et. al., say:

“Europeans and East Asians have very similar ROH profiles in all but the shortest category (0.5-1 Mb). There are no significant differences between either the percentage of individuals with ROH of different lengths or sum length of ROH above different length thresholds (>1.5 Mb) for these two continental groupings (File S1). This is not surprising because both of these groups are mainly represented here by fairly large populations with no documented preference for consanguineous marriage.

ehhhhhhh … well … if they’re talking about now, i.e. in the present, then yeah — that’s probably pretty right. but many of the european populations that they looked at (i.e. from the human genome diversity project [hgdp]), regularly practiced some to quite a lot of consanguineous marriages up until fairly recently. (i haven’t checked into the asian populations that they looked at.)

the european populations that they looked at are: the adygeis, the basques, french folks, italians, orcadians, russians, sardinians and tuscans.

the adygeis are the circassians and it’s my understanding that they have avoided cousin marriage for quite some time, although they are endogamous (obviously). the russians — religious russians, anyway — avoid first- and second-cousin marriage. but the basques and the french have had some signficant amounts of consanguineous marriage up until quite recently. and the italians and sardinians?! holy toledo! of all of these groups, it’s probably the tuscans that have avoided cousin marriage for the longest. (dunno about the orkney islanders.)

like i said yesterday, if anything, kirin, et. al., have probably got some of the most inbred europeans in their sample.

anyway … i took at look at their supplemental info [opens pdf] and found that they’ve included data for the proportion (percentage) of the genomes from each group that are covered in “runs of homozygosity” (roh). the more roh in your — or your population’s — genome(s), the more inbred you (all) are (or maybe the smaller your gene pool is — see yesterday’s post). when i took out just the europeans plus the han chinese and japanese and a couple of other interesting groups, here’s what i got:

most of the european groups have the least number of roh (these are roh of all different lengths). the han chinese are like the italians or the sardinians, who have a long and recent history of close marriages (not so much the northern italians) — and the japanese even more so. wikipedia tells us that cousin marriage was preferred in china until the mid-twentieth century, so there you go.

and the father’s brother’s daughter’s marriage groups? their roh are higher than the inbred europeans, the han chinese and the japanese.

you can see here, too, that the japanese have greater numbers of longer roh than french people (the black circles are the japanese, the orange circles are the french) — that means more recent inbreeding amongst the japanese (click on image for LARGER view – should open in new tab/window):

interestingly, many balochis (green circles) have fewer and shorter roh than the french — many have more and longer. dunno what that tells us about the balochi. new blood? tribes merging with (fairly) unrelated tribes? just plain ol’ out-marriage?

here are the percentages of the genomes covered by roh for each of the populations in the study in ascending order. i tried to match the colors for the continental groupings from the chart in yesterday’s post — dunno if i succeeded?:

previously: runs of homozygosity and inbreeding (and outbreeding)

(note: comments do not require an email. balochi farmer. (^_^) )