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 – 10/27/13

Ancient DNA Links Native Americans With Europe“…from the complete nuclear genome of a Siberian boy who died 24,000 years ago — the oldest complete genome of a modern human sequenced to date. His DNA shows close ties to those of today’s Native Americans. Yet he apparently descended not from East Asians, but from people who had lived in Europe or western Asia. The finding suggests that about a third of the ancestry of today’s Native Americans can be traced to ‘western Eurasia,’ with the other two-thirds coming from eastern Asia…. It also implies that traces of European ancestry previously detected in modern Native Americans do not come solely from mixing with European colonists, as most scientists had assumed, but have much deeper roots.” — see also: The First of the Mohicans from greg cochran.

Your face may have been sculpted by junk DNA“There is a huge degree of variation in human faces but, as family resemblances show, the overall shape is heavily constrained by genetics. However, so far, geneticists have identified only a small number of genes that influence the shape. These explain just a tiny fraction of the variation seen in human faces. According to Axel Visel of the Lawrence Berkeley National Laboratory in California and his colleagues, more variation is controlled by distant-acting enhancers. These are short sequences of DNA, in non-coding regions of the genome, that can influence the activity of the facial genes, even if they are a long way along the DNA strand.”

Behavior problems in preschool and child care centers may be an issue of genes“A new study suggests that some children may be genetically predisposed to developing behavioral problems in child care and preschool settings…. [B]irth parents who had high rates of negative emotion and self-control, based on a self-reported temperament scale, were more likely to have children who struggled with behavioral issues such as lack of self-control and anger, in child care centers. They controlled for adoptive parent’s characteristics, and still found a modest effect based on the genetic link.”

Your Ethnicity Determines the Species of Bacteria That Live in Your Mouth“[P]eople from each of the four different ethnic groups represented in the study (all participants self-identified as either Caucasian, African-American, Chinese or Latino) generally had similar species of bacteria, especially underneath the gums. As a result, simply by counting which varieties of bacteria appeared in this area, the researchers developed a model that was able to guess a person’s ethnicity with an accuracy significantly better than chance — it got it right 62 percent of the time. Some groups were even easier to identify via the bacteria than others: It could correctly identify Latinos 67 percent of the time and African-Americans with 100 accuracy. The variation along ethnic lines, they believe, is a reflection of genetics, not environment. That’s because, if you assumed that the mouth microbiome is totally dependent on environmental factors, you’d expect that members of the same ethnic group would have different mixes of bacteria depending on whether they were first-generation immigrants to the U.S. or had family histories that stretched back generations in the country. Instead, people’s background — in terms of foods they ate and other lifestyle trends — didn’t seem to have any correlation with the bacterial communities in their mouths. – h/t super bob!

Herpes virus genome traces the ancient path of human migration“Researchers…sequenced the genomes of 31 samples of herpes simplex virus type-1 to reconstruct how it hitchhiked on humans as they dispersed around the world. The results match the pattern proposed by the ‘Out of Africa’ theory, which has become the most widely accepted scenario for ancient human migration. The analysis showed that African strains of the virus contained the most genetic diversity — suggesting that they had the oldest roots.”

Genetic variation alters efficacy of antidepressant“Having a different form of a gene that regulates the brain chemical noradrenaline influences how well men remember negative memories after taking the antidepressant drug reboxetine, according to a study published in the October 23 issue of The Journal of Neuroscience. The findings demonstrate how genes can influence antidepressant response.” – see also: Genes predispose some people to focus on the negative.

Much Earlier Split for Neanderthals, Humans?“This suggests that the last common ancestor of H. sapiens and Neanderthals lived sometime earlier, perhaps as far back as one million years ago.”

Denisovans in Wallacea? – from greg cochran.

Life on Earth Was Not a Fluke“Figuring out how biomolecular self-organization happens may hold the key to understanding life on Earth formed and perhaps how it might form on other planets.” – h/t jayman!

Genetics made very simple – from dr. james thompson.

Low historical rates of cuckoldry in a Western European human population traced by Y-chromosome and genealogical data“[W]e estimate that over the last few centuries, EPP rates in Flanders (Belgium) were only around 1–2% per generation. This figure is substantially lower than the 8–30% per generation reported in some behavioural studies on historical EPP rates, but comparable with the rates reported by other genetic studies of contemporary Western European populations. These results suggest that human EPP rates have not changed substantially during the last 400 years in Flanders and imply that legal genealogies rarely differ from the biological ones.” – h/t rob brooks!

‘Endowment Effect’ Not Present in Hunter-Gather Societies“‘The more isolated Hadza traded about 50 percent of the time — which is what rational people should do,’ Azevedo said. People near the village traded about 25 percent of the time, which is much closer to the 10 percent we see with Western students.” – h/t jason collins! – previously: personality goes a long way… in which researchers find just big TWO personality traits in a group of hunter-gatherers (the tsimane).

speaking of the tsimane: UCSB anthropologist studies the evolutionary benefit of human personality traits“‘Being more extroverted, open, agreeable and conscientious –– and less neurotic –– was associated with having more kids.'” in tsimane men. (if they really have all those personality traits…see link immediately above.)

What Happens When a Language Has No Numbers? – on the pirahã. – h/t nn!

Can Your Genes Predict Whether You’ll Be a Conservative or a Liberal?“Scientific research shows political partisanship transcends economics, environment, and upbringing.” – from avi tuschman.

Life expectancy and the dawn of agriculture – from jason collins.

Origins of Americans (Looking At HLA Haplotypes) – from our very own chris davies! previously from chris: human leukocyte antigen (hla) haplotypes and human biodiversity.

Number sense in infancy predicts mathematical abilities in childhood“Preverbal number sense in 6-month-old infants predicted standardized math scores in the same children 3 years later. This discovery shows that number sense in infancy is a building block for later mathematical ability and invites educational interventions to improve number sense even before children learn to count.” – h/t simon baron-cohen!

Black Suits, Gowns, & Skin: SAT Scores by Income, Education, & Race – @the unsilenced science. see also: Obama Administration: Moynihan’s Law of Canadian Border kinda right from steve sailer.

Of Race and Intelligence – from helian.

Sex on the Mind“It is a truth universally acknowledged — at least by biologists — that every person owes his or her existence to parents who successfully reproduced, each of whom, in turn, had two parents who did the same … and so on, going back hundreds of millions of years to the first ancestral blob (or two) of protoplasmic goo that trundled onto terra firma from the early earth’s organic soup.” – from david barash. — see also: Why Have Sex? – from the advanced apes.

Lust Is Love – from heartiste.

Kids Are More Likely to Trust Attractive Adults – h/t hbd bibliography!

Asymmetries in altruistic behavior during violent intergroup conflict“Some empirical studies on intergroup conflict in hunter-gatherer societies and chimpanzees indicate that fitness relevant risks and potential benefits of attacks and defenses might have differed substantially under ancestral conditions. Drawing on these studies, it is hypothesized that the success of defenses was much more important for individual and kin survival and that a disposition to act altruistically during intergroup conflict is thus more likely to evolve for the strategic situation of defense…. Analyzing detailed historical case data from 20th century wars, this study finds that altruistic behavior towards members of the in-group indeed seems to occur more frequently when soldiers are defending themselves and their comrades against enemy attacks.” – h/t hbd bibliography!

Who gives? Multilevel effects of gender and ethnicity on workplace charitable giving.“[E]thnic minorities donate less money to workplace charity than do Whites.” – and men less than women. – via richard lynn @amren.

Paradoxes of the Nordic Model II“Denmark is a high trust, highly cooperative society. There is very low crime. Most parked bicycles are not even locked. Bank employees may not work very efficiently, but nobody tried to swindle me. In theoretical terms, what it means is that when there are very few defectors, the amount of common good produced overall is maximized. So everybody is well of, even though they don’t work hard – but they don’t free-ride, either….” – from peter turchin.

Ma’am, Your Burger Has Been Paid For – paying it forward in america! – h/t charles murray!

Napoleon Chagnon: The Fierce Sociobiologist“[Yanomamo] Men from the highland villages were much less belligerent than men from villages along the river. Heterogeneity in belligerence existed even within this single tribe.”

Where Have All the Geniuses Gone?

Aboriginal Hunting Practice Increases Animal Populations – monitor lizards, anyway.

“Science has lost its way, at a big cost to humanity“Researchers are rewarded for splashy findings, not for double-checking accuracy. So many scientists looking for cures to diseases have been building on ideas that aren’t even true.” – h/t outsideness! – see also: Trouble at the lab“Scientists like to think of science as self-correcting. To an alarming degree, it is not.”

These Unresolved Ethical Questions Are About to Get Real

bonus: Hunted by their own government – the fight to save Kalahari Bushmen“Survival International, which campaigns on behalf of tribal peoples, has called for tourists to boycott holidays in Botswana, which is forcing Kalahari Bushmen off their reserves.”

bonus bonus: How did ancient Greek music sound? – beautiful apparently! – h/t ed west!

bonus bonus bonus: Author: In China, ‘everyone is guilty of corruption’ – on guanxi.

bonus bonus bonus bonus: The couple having four babies by two surrogates“A British couple are to become parents of two sets of twin babies carried by two Indian surrogate women they have never met. Experts say twiblings – or children born to separate surrogates but created from the same batch of embryos – are not uncommon in India.”

bonus bonus bonus bonus bonus: Gang Rape in India, Routine and Invisible“[T]he Mumbai case provides an unusual glimpse into a group of bored young men who had committed the same crime often enough to develop a routine. The police say the men had committed at least five rapes in the same spot. Their casual confidence reinforces the notion that rape has been a largely invisible crime here, where convictions are infrequent and victims silently go away.” – see also: Trying to Make Sense of India’s Sexual Violence, State by State from t.greer.

bonus bonus bonus bonus bonus bonus: Insects aren’t gay, they’re just enthusiastic! Scientists discover same-sex mating in bugs is down to a rush to reproduce – h/t hbd bibliography!

bonus bonus bonus bonus bonus bonus bonus: Mysterious hum keeping people up all night ‘could be mating fish’“A council investigation was launched in Hythe, Southampton after some people had to move away because of the drone ‘pulsating’ through their homes.”

bonus bonus bonus bonus bonus bonus bonus bonus: Are conspiracy theories destroying democracy?“The more information we have about what governments and corporations are up to the less we seem to trust them. Will conspiracy theories eventually destroy democracy?” – h/t avi tuschman!

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