linkfest – 01/21/14

Calcium absorption not the cause of evolution of milk digestion in Europeans“‘The evolution of lactase persistence is one of the best known and most dramatic examples of recent human evolution. One of the ironies of working in this area is that we know it happened but we still don’t fully know why’ says Sverrisdóttir. Lactase persistence is found at highest frequencies in southern Sweden and in Ireland. Given that calcium absorption is not the only reason why this trait evolved so rapidly, Sverrisdóttir and colleagues have proposed another cause: Although most early European farmers would not have been lactase persistent, they would still have been able to consume fermented milk products such as yoghurt and cheese, because fermentation converts much of the lactose into fats. But in famine conditions, such as when crops fail, they are likely to have eaten all the fermented milk foods, leaving only the more high-lactose products. This would have caused the usual lactose intolerance symptoms such as diarrhea. Diarrhea in in healthy people is not usually life-threatening, but in severely malnourished individuals it certainly can be. So famine could have led to episodes of very strong natural selection favoring lactase persistence.”

Human and Helicobacter pylori coevolution shapes the risk of gastric disease“Patients were recruited from two geographically distinct Colombian populations with significantly different incidences of gastric cancer, but virtually identical prevalence of H. pylori infection. All H. pylori isolates contained the genetic signatures of multiple ancestries, with an ancestral African cluster predominating in a low-risk, coastal population and a European cluster in a high-risk, mountain population. The human ancestry of the biopsied individuals also varied with geography, with mostly African ancestry in the coastal region (58%), and mostly Amerindian ancestry in the mountain region (67%). The interaction between the host and pathogen ancestries completely accounted for the difference in the severity of gastric lesions in the two regions of Colombia. In particular, African H. pylori ancestry was relatively benign in humans of African ancestry but was deleterious in individuals with substantial Amerindian ancestry. Thus, coevolution likely modulated disease risk, and the disruption of coevolved human and H. pylori genomes can explain the high incidence of gastric disease in the mountain population.”

Seeing X Chromosomes in a New Light“X-chromosome inactivation, Dr. Nathans’s pictures show, creates a genetic diversity that’s particularly dramatic. Two cells side by side may be using different versions of many different genes. ‘But there is also much larger-scale diversity,’ Dr. Nathans said. In some brains, for example, a mother’s X chromosome was seen dominating the left side, while the father’s dominated the right. Entire organs can be skewed toward one parent. Dr. Nathans and his colleagues found that in some mice, one eye was dominated by the father and the other by the mother. The diversity even extended to the entire mouse. In some animals, almost all the X chromosomes from one parent were shut; in others, the opposite was true.”

Are plants altruistic?“Roots can distinguish self from other, and they know their own kind (species), they can share resources and information about insect attacks and deliver nutrients to trees in need. The preponderance of evidence does seem to suggest that plants are proactive in filling their own needs and the needs of others.” – ooooh, not just their own species, their own close relatives! – see also The Intelligent Plant.

Sluggish metabolisms are key to primates’ long lives“[P]rimates expend 50 per cent less energy than other mammals of equivalent mass during an average day. ‘What’s more, he says the difference is not easily explained by differing activity levels: a human would need to run a whole marathon every day to be on an even energetic footing with mammals that aren’t primates….’ The finding offers a completely new way to understand why primates have slower life histories than other mammals of equivalent body size…. Pontzer thinks that the slower metabolism may have evolved to help primates cope with food shortages. For instance, orang-utans suffer frequent famines. ‘Orang-utans experience extended periods of low fruit availability,’ says Vogel. ‘There are months when caloric intake is less than expenditure – and they burn body fat stores.’ A slow metabolism might help them survive.”

Triune origins“With the latest paper, the story on European origins is becoming clearer. Three populations account for European ancestry: the Mesolithic hunter-gatherers of western Europe (dubbed WHG in the paper), early European farmers derived from somewhere in the Mideast (EEF), and a third group more closely related to ancient Siberians (ANE) than any existing population. Those Sibermen also contributed a third of Amerindian ancestry, the rest being similar to modern East Asian populations.” – from greg cochran.

The first industrial revolution“As early modern humans spread farther north, they entered more challenging environments…. Did these new cognitive demands have an evolutionary impact? Did they select for certain mental capacities over others? Piffer (2013) has addressed these questions by seeing how hunter-gatherers differ from farming peoples in alleles at COMT, a gene linked to executive function, working memory, and intelligence…. Northern hunting peoples, however, differ from other hunter-gatherers and resemble more advanced farming populations.” – from peter frost.

‘Out of Africa’ gene mutation in human pigmentation increases predisposition to skin cancer“The V60L mutation is more common in people with light hair and skin tone that, despite being light, tans easily in the summer. This mutation is positive for the climate of the Mediterranean region, as it facilitates the absorption of vitamin D in the winter months, in which the ultraviolet radiation is lower. In the summer months, in which the radiation is greater, the ease to darken the skin pigmentation provides a certain protection. However, the study also revealed that among people with this mutation there is a greater predisposition to skin cancer.” – see also: Simultaneous Purifying Selection on the Ancestral MC1R Allele and Positive Selection on the Melanoma-Risk Allele V60L in South Europeans.

Longitudinal four-dimensional mapping of subcortical anatomy in human development – h/t kevin mitchell! who said: “Large imaging study details substantial sex differences in maturation dynamics of subcortical structures.” – also: Fundamental sex difference in human brain architecture [behind paywall].

Changes in Thickness and Surface Area of the Human Cortex and Their Relationship with Intelligence“At 10 years of age, more intelligent children have a slightly thinner cortex than children with a lower IQ. This relationship becomes more pronounced with increasing age: with higher IQ, a faster thinning of the cortex is found over time. In the more intelligent young adults, this relationship reverses so that by the age of 42 a thicker cortex is associated with higher intelligence. In contrast, cortical surface is larger in more intelligent children at the age of 10. The cortical surface is still expanding, reaching its maximum area during adolescence. With higher IQ, cortical expansion is completed at a younger age; and once completed, surface area decreases at a higher rate. These findings suggest that intelligence may be more related to the magnitude and timing of changes in brain structure during development than to brain structure per se, and that the cortex is never completed but shows continuing intelligence-dependent development.”

Why do spatial abilities predict mathematical performance?“About a third of the variation in spatial ability at age 12 is explained by genetic factors; a little less than half of the variation in mathematics at this age is genetic. We find no sex differences in the genetic and environmental influences (either in magnitude or type) on mathematical and spatial variation at age 12. The observed overlap between spatial ability and mathematics is substantial (r > .40). Approximately 60% of this overlap is explained by common genetic effects, with 40% of the overlap due to environmental experience.” – h/t DOCTOR stuart ritchie! (^_^)

New evidence shows the FDA was wrong to halt 23andMe testing“While the tests are often too inaccurate for consumers to consider them diagnoses, research shows that most customers will seek a doctor’s opinion before taking action, anyway. According to the authors’ research, 58% of 1,051 surveyed customers did nothing at all with their genomic results. Of the 42% who made health decisions based on the information, only 2% changed prescription drug regimens without consulting a physician. The majority of customers who made changes focused on diet, exercise, and vitamins.”

Dogs’ Closest Wolf Ancestors Went Extinct, Study Suggests” A new genetic analysis of modern dogs and wolves suggests that man’s best friend was domesticated before agriculture. But the origin of this domestication remains stubbornly mysterious. Researchers analyzed the genomes of wolves from three likely sites of domestication (the Middle East, Asia and eastern Europe), and found that modern dogs were not more closely related to any of the three. In fact, it seems that the closest wolf ancestors of today’s dogs may have gone extinct, leaving no wild descendants.” – also: Paedomorphic Facial Expressions Give Dogs a Selective Advantage – woof! – h/t claire lehmann!

The Nurture Enigma – How Does the Environment Influence Human Nature? – from staffan.

The interplay of genetic and cultural evolution – from jason collins.

Eye of the Tiger PeopleBut what the hell is ‘culture,’ anyway? Talk about a social construct! Even the term ‘social construct’ is a social construct, one unique to our culture. And who’s to say culture is entirely separate from genetics? There’s some suggestion that the two may be intimately intertwined. In rawest terms, ‘culture’ may be nothing more than what happens when a group’s genes interact with their environment. – from jim goad.

Toddlers’ aggression is strongly associated with genetic factors, study reports“The development of physical aggression in toddlers is strongly associated genetic factors and to a lesser degree with the environment, according to a new study led by Eric Lacourse of the University of Montreal and its affiliated CHU Sainte-Justine Hospital. Lacourse’s worked with the parents of identical and non-identical twins to evaluate and compare their behaviour, environment and genetics.” – h/t mr. mangan, esq!

Modifying DNA May Wipe Away Old Memories – so can several double gin and tonics in a row. (~_^) – they’re talking about epigenetic changes here, btw.

Apes are intuitive statisticians“Here, we conducted the first investigation of such intuitive statistical reasoning with non-human primates. In a series of 7 experiments, Bonobos, Chimpanzees, Gorillas and Orangutans drew flexible statistical inferences from populations to samples. These inferences, furthermore, were truly based on statistical information regarding the relative frequency distributions in a population, and not on absolute frequencies. Intuitive statistics in its most basic form is thus an evolutionarily more ancient rather than a uniquely human capacity.” – iow, the other great apes outperform a lot of humans (i.e. the pc ones)! (~_^) – h/t neuroskeptic!

Study: Chimpanzees Bond Over Shared Meals“[C]himps who share their food have higher levels of oxytocin, known as the love hormone, than those who don’t.” – h/t hbd bibliography!

Comedians have psychotic personality traits, study finds“In a study in the British Journal of Psychiatry, researchers analyzed comedians from Australia, Britain and the United States and found they scored significantly higher on four types of psychotic characteristics compared to a control group of people who had non-creative jobs. The traits included a tendency towards impulsive or anti-social behavior, and a tendency to avoid intimacy. ‘The creative elements needed to produce humor are strikingly similar to those characterizing the cognitive style of people with psychosis – both schizophrenia and bipolar disorder,’ said Gordon Claridge of the University of Oxford’s department of experimental psychology, who led the study.”

Natural selection can favour ‘irrational’ behaviour – well, there’s your problem!

‘Human evolution likely led to rise of religion’ – h/t holly dunsworth! whose response was: duh! (~_^)

New study finds mistimed sleep disrupts rhythms of genes in humans“During this disruption of sleep timing, there was a six-fold reduction in the number of genes that displayed a circadian rhythm (a rhythm with an approximately 24 hour period). This included many regulators associated with transcription and translation, indicating widespread disruption to many biological processes.” – sleep right!

speaking of which: Study finds later school start times improve sleep and daytime functioning in adolescents – h/t anatoly!

The human brain can process images the eye sees for 13 milliseconds – imagine how quickly THE FLASH’s brain can process images!! (~_^)

The Islamic Republic of Baby-Making“Iran, like other Middle Eastern countries, has an extremely high infertility rate. More than 20 percent of Iranian couples cannot conceive, according to a study conducted by one of the country’s leading fertility clinics, compared with the global rate of between 8 and 12 percent. Experts believe this is due to the prevalence of consanguineous marriages, or those between cousins. Male infertility is ‘the hidden story of the Middle East,’ says Marcia Inhorn, a Yale University medical anthropologist and a specialist on assisted reproduction in the region.”

This Language Names Odors As Precisely As English Speakers Name Colorjahai speakers in malaysia. – h/t t.greer! – see also: Can You Name That Smell?“It’s also possible that the Jahai are built differently than the rest of us. The genes that code for the olfactory receptors in our noses exhibit a great deal of variation not only between different human populations but also between people. So it may be that the Jahai have evolved more of these receptors or a greater diversity of them than everyone else, much like the Tsimane tribe from the Bolivian rainforest were shown to be more sensitive to smells than were Germans.”

Gene therapy ‘could be used to treat blindness’“Surgeons in Oxford have used a gene therapy technique to improve the vision of six patients who would otherwise have gone blind. The operation involved inserting a gene into the eye, a treatment that revived light-detecting cells.”

The thinnest Americans are Asian Americans, CDC data show – surprise!

Shapely centrefolds? Temporal change in body measures: trend analysis – h/t ben southwood! who said: “Playboy centrefolds’ waists have widened, weights have fallen, busts have shrunk and hips have narrowed since 1953.”

Study: Violence, infectious disease and climate change contributed to Indus civilization collapse – h/t mike anissimov!

What was in that grog? Scientists analyze ancient Nordic drink“Ancient Scandinavians quaffed an alcoholic mixture of barley, honey, cranberries, herbs and even grape wine imported from Greece and Rome, new research finds.” – mmmmmm! mmmmmm?

bonus: i’m a journalist! – h/t jayman!

bonus bonus: and a neo-fascist, too, apparently. hahahahahahahaha!! *snort*

bonus bonus bonus: Genetically engineered plant glows so brightly it can be used as a LAMP

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linkfest – 04/21/13

Inbred royals show traces of natural selection“Study suggests the Spanish Habsburgs evolved to mute the effects of inbreeding, but other geneticists are unconvinced.”

Time to get tough on the physiological causes of crime“[V]iolent criminals are biologically different from the rest of us.” – review of The Anatomy of Violence: The Biological Roots of Crime.

Scientists find ethnicity linked to antibodies“‘[I]t’s early days,’ emphasizes Watson, ‘but these findings could mean that past environmental exposures to certain pathogens caused DNA insertions or deletions in different ethnic groups, which could impact disease risk. Our results demonstrate that antibody studies need to take into account the ethnicity of DNA samples used.'”

Those resistant to ‘love hormone’ may also be easier to hypnotize“Gene variants linked to social detachment may increase suggestibility.”

One Blessing Of Outbreeding – i didn’t write this, i swear! (you’ll never guess who did…)

The gay germ hypothesis – from peter frost. see also Not Final! from greg cochran.

Another reminder…“[A] prod to certain of my smart liberal friends to start having children.” – from jayman. see also: The end of paternal investment or, more cads, fewer dads from mr. mangan.

The Strange Case of Dr. Robert Trivers“[Trivers] has been driven off the campus of Rutgers University! He has been involved in a controversy lately over his accusation that one of his graduate students committed fraud in a scientific paper. Apparently he was banned from campus because a colleague who supports the alleged fraudster claimed Trivers had ‘frightened him in his office’.” – from helian unbound.

Women graduates of elite colleges 1/3rd more likely to be stay-at-home moms – from steve sailer.

Scent of a Man: Women Can Sniff Out a Hot Guy“Women at their peak fertility prefer the smell of men oozing with testosterone, a new study finds.” – and speaking of testosterone: Testosterone pumps up threats for tough guys“The higher a man’s testosterone level, the more macho he’s likely to act when his masculinity is threatened, a new study finds.”

The Real ‘Hobbit’ Had Larger Brain Than Thought

Egyptian mummies yield genetic secrets“The ancient Egyptians could soon be getting their genomes sequenced as a matter of routine.”

Why Menopause?

Stonehenge occupied 5,000 years earlier than thought

The Pattern of Female Nuptiality in Oman“[M]ore than half (52%) of the total marriages in Oman are consanguineous. First cousin unions are the most common type of consanguineous unions, constituting 39% of all marriages and 75% of all consanguineous marriages. About 11% of the marriages are polygynous…. [P]aternal first-cousin marriages constituted 27.7% of all marriages and 72% (565/786) of all first-cousin marriages, while maternal first-cousin marriages constituted 10.8% of all marriages and 28% (221/786) of all first-cousin marriages.”

The Ancient Greeks & Romans, Beauty and Human Biodiversity – @occam’s razor.

Could Life Be Older Than Earth Itself?“[T]wo geneticists have applied Moore’s Law to the rate at which life on Earth grows in complexity — and the results suggest organic life first came into existence long before Earth itself.”

Chimps Communicate Like Passionate Italians – my favorite headline of the week. (^_^)

Live fast, die younger: Actors, singers and sportsman ‘die seven and a half years before other high achievers’

Historic human remains yield epigenetic tags – see also: Epigenetic Inheritance: Fact or Fiction?

Icelandic anti-incest app keeps residents from becoming kissin’ cousins – previously íslendingabók.

‘Real men wear kilts’: The anecdotal evidence that wearing a Scottish kilt has influence on reproductive potential: how much is true? – keep wearin’ yer kilt!

Did this magical little crystal help the Vikings rape and pillage across the world?“Research suggests crystal salvaged from a shipwreck may be a sunstone”

bonus: What rights should Dzhokhar Tsarnaev get and why does it matter?“The Obama DOJ says it intends to question the Boston bombing suspect ‘extensively’ without first Mirandizing him”

bonus bonus: Applicants wanted for a one-way ticket to Mars – let’s go! (^_^)

bonus bonus bonus: ‘Living fossil’ genome unlocked“The genes of an ancient fish, the coelacanth, have much to reveal about our distant past.”

bonus bonus bonus bonus: Chlamydia Is Killing Koalas — Will Genetics Find a Cure?

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silly refutations of kanazawa’s blog post

there’ve been a lot — a LOT — of refutations of kanazawa’s post on the attractiveness of black women. i haven’t read them all — in fact i’ve read hardly any of them ’cause most of them just scream and yell WAAAAAAYCIST!! BURN HIM, BURN HIM!!

*facepalm*

some of them, however, appear to be more scientific refutations. bering in mind links to another psychology today blogger (scott barry kaufman) who (along with someone named jelte wicherts in the netherlands) has supposedly (according to bering in mind) “failed to replicate” kanazawa’s findings.

i took at look at kaufman’s post — and the technical summary of their analysis — ’cause i thought, well gee — not able to replicate the findings — that’d be interesting.

IF IT WERE TRUE!

here’s the evidence that kaufman and wicherts present (in the blog post) to show that kanazawa’s analysis was incorrect:

looks like black women were rated nearly as attractive as white women, right? and they were. in wave iv.

here’s how they fudged the data.

the add health thingie (from whence all the data comes) involved four waves of surveys over the course of several years (a couple of decades?). kaufman and wicherts decided that the only wave that should be included in any analysis on the attractiveness of women is wave iv, because in that wave the females were of legal age and, therefore, women.

no, i’m not kidding. they really said that!

now, i would agree with them if the subjects in the previous waves had been pre-pubescent children. but the ages in the waves were:

wave i = mean age 15.9 years
wave ii = average age 16.5 years
wave iii = mean age 22.1 years
wave iv = mean age 28.9 years

now come on! ok, so in waves i-iii most or all of the subjects were not of legal age, but probably the vast majority (except maybe for some late bloomers in wave i) were “reproductively of age” — meaning they could make babies. which is what the whole discussion is about! attractiveness, after all, is about attracting a mate.

*cough, cough* cherry-picking *cough, cough*

kanazawa didn’t include wave iv in his analysis, which is the wave when the attractiveness of whites and blacks was rated the most similar. don’t know why he didn’t use the data from that wave. kaufman mentions that the data from that wave has been available “for over a month.” well, maybe kanazawa didn’t realize the newest data had been published when he ran his analysis. i really dunno, but it’s definitely possible.

in any case, waves i-iii show that black women were rated as less attractive, altho i think the numbers in wave iii are not statistically significant. in wave iv, as i’ve said above, the rating for whites and blacks were pretty similar:

i still wanna know who the interviewers|evaluators were. were they all white folks? all asians? all illegal mexican workers picked up outside home-depot? their characteristics might’ve influenced the results.

actually, now that i mention it, the fieldwork for waves iii and iv was contracted out to a different company than waves i and ii. wonder if that made any difference in the evaluations?

btw, some real word data from okcupid maybe lends more support to kanazawa’s findings:

“Men don’t write black women back. Or rather, they write them back far less often than they should. Black women reply the most, yet get by far the fewest replies. Essentially every race—including other blacks—singles them out for the cold shoulder.”

that’s too bad.

previously: the offensive mr. kanazawa and african-american porn stars

update 06/07: see also on the add health interviewers

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the offensive mr. kanazawa

you prolly heard by now that satoshi kanazawa says black women are ugly.

of course, he didn’t really, but who cares about silly little ol’ details like that.

what happened was kanazawa got some “attractiveness” data from add health. the evaluations were made “three times by three different interviewers over seven years” (during waves i – iii). the data showed that, consistently, black females scored lower in attractiveness than white, asian, or native american women; this did not happen in the case of black males.

andrew over @evolvify makes a good point about how attractiveness was rated:

“At this point, we have no idea who the interviewers who rated the students were. The attractiveness ratings would have been altered by varying degrees of prior familiarity between the individuals… whether the interviewers were of a certain age… the same sex or opposite sex breakdown… ingroup/outgroup… interviewer race… et cetera. There are simply a lot of variables that bring the reliability of attractiveness data into question. Perhaps this information is available, but it wasn’t in Kanazawa’s article, and I couldn’t find it on the study’s website.”

well, add health (a university of south north carolina entity) apparently outsourced its fieldwork positions to both the national opinion research center (norc) of the university of chicago (waves i and ii) and rti international (wave iii).

fieldworkers seem to be part-time, contract workers, afaics. with the connection to the unversity of south north carolina and the university of chicago, i was guessing that the fieldworkers were likely college students — maybe grad students interested in the field — sociology or whatever the heck it is (i’m talking about the interviewers here — i realize that the add health people are in the medical field). and, who winds up in sociology? mostly white women, with perhaps a few asian women thrown in. so, i was thinking that a lot of the interviewers might’ve been young white college women — and they might not find black women to be very attractive.

however, on the norc website, there are some videos of field interviewers explaining why they love their job, etc., etc., and they’re all older folks, i.e. not college students. of course, i’m sure this group is a pc-selected group — they’ve got almost all the races included there. but, still, three out of the five are white folks. if that is at all representative, then, yeah — there could, again, very well be some bias introduced here.

it’s still interesting that black women were consistently evaluated as the least attractive, but who were the evaluators? if they had been all black men, perhaps the results would’ve been different.

what i think is even more interesting is that blacks — both men and women — consistently rated themselves as attractive or highly attractive, more than members of the other races. black and proud! good for them!:

update 05/19 – charts with y-axes starting at zero:

update – see also ANOTHER watsoning in the air?!

update 05/27 – wicherts and kaufman’s criticism of kanazawa’s number crunching: An independent analysis of race differences in ratings of attractiveness in the Add Health Study. “Kanazawa interpreted his results incorrectly as having a bearing on attractiveness of women because the ratings were taken mostly when Add Health participants were teenagers.” update 06/07: see silly refutations of kanazawa’s blog post

update 06/07: see also on the add health interviewers

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