Friday, November 15, 2019

Explaining the puzzle of human diversity in the Christian world

Fascinating work by Schulz et al. is reviewed by both Gelfand and also Zauzmer. Schultz et al. show how the specific practices of Medieval Christianity can in part explain widespread variation in human psychology around the world.

From Zauzmer:
The story begins with kinship networks — the tribes and clans of densely connected, insular groups of relatives who formed most human societies before medieval times. Catholic Church teachings disrupted those networks, in large part by vehemently prohibiting marriage between relatives (which had been de rigeur), and eventually provoked a wholesale transformation of communities, changing the norm from large clans into small, monogamous nuclear families.
The team analyzed Vatican records to document the extent of a country or region’s exposure to Catholicism before the year 1500, and found that longer exposure to Catholicism correlated with low measures of kinship intensity in the modern era, including low rates of cousins marrying each other. Both measures correlated with psychology, the researchers found by looking at 24 different psychological traits of people in different cultures: Countries exposed to Catholicism early have citizens today who exhibit qualities such as being more individualistic and independent, and being more trusting of strangers.
From Gelfand:
...the authors found that both longer exposure to the Western Church and weaker kinship intensity (which were negatively related, as expected) were associated with greater individualism and independence, less conformity and obedience, and greater prosociality toward strangers—relationships that mostly held when controlling for a range of geographic variables. The results were replicated across 440 regions in 36 European countries: Longer exposure to the Western Church was generally associated with the same WEIRD (Western, Educated, Industrialized, Rich and Democratic) psychological shifts, even when controlling for alternate explanations (e.g., the influence of Roman political institutions, schooling, migration).

Wednesday, November 13, 2019

New work on how and why we sleep.

The fact that I'm finding the quality of my sleep to be central to my robustness and well-being makes me want to pass on descriptions of four pieces of work described in recent issues of Science Magazine, work showing housekeeping changes in our brains happening while we sleep, changes whose disruption by sleep deprivation has debilitating consequences. Fultz et al. show that deep sleep drives brain fluid oscillations that may facilitate communication between fluid compartments and clearance of waste products. Todorova and Zugaro show that spikes during delta waves of sleep (widespread cortical silence) support memory consolidation. BrĂ¼ning et al. find in the mouse brain that half of the 2000 synaptic phosphoproteins quantified show changes with daily activity-rest cycles. Sleep deprivation abolishes nearly all (98%) of these phosphorylation cycles at synapses. Noya et al. find a sleep-wake cycle in which transcripts and proteins associated with synaptic signaling accumulate before the active phase (dusk for nocturnal mice), whereas messenger RNAs and proteins associated with metabolism and translation accumulate before the resting phase.

Monday, November 11, 2019

Why we can't tell the truth about aging.

I've enjoyed reading the New Yorker essay by Arthur Krystal titled "Why we can't tell the truth about aging," which points to and discusses numerous recent (as well as a few ancient) books on aging. Here is a selection of rearranged small clips from the article.
Average life expectancy was indeed a sorry number for the greater part of history (for Americans born as late as 1900, it wasn’t even fifty), which may be one reason that people didn’t write books about aging: there weren’t enough old folks around to sample them. But now that more people on the planet are over sixty-five than under five, an army of readers stands waiting to learn what old age has in store.
Now that we’re living longer, we have the time to write books about living longe...The library on old age has grown so voluminous that the fifty million Americans over the age of sixty-five could spend the rest of their lives reading such books, even as lusty retirees and power-lifting septuagenarians turn out new ones.
Our senior years are evidently a time to celebrate ourselves and the wonderful things to come: travelling, volunteering, canoodling, acquiring new skills, and so on. No one, it seems, wants to disparage old age...we get cheerful tidings...chatty accounts meant to reassure us that getting old just means that we have to work harder at staying young...authors aren’t blind to the perils of aging; they just prefer to see the upside. All maintain that seniors are more comfortable in their own skins.
There is, of course, a chance that you may be happier at eighty than you were at twenty or forty, but you’re going to feel much worse. I know this because two recent books provide a sobering look at what happens to the human body as the years pile up. Elizabeth Blackburn and Elissa Epel’s “The Telomere Effect: Living Younger, Healthier, Longer” and Sue Armstrong’s “Borrowed Time: The Science of How and Why We Age” describe what is essentially a messy business.
Basically, most cells divide and replicate some fifty-plus times before becoming senescent. Not nearly as inactive as the name suggests, senescent cells contribute to chronic inflammation and interfere with protective collagens...The so-called epigenetic clock shows our DNA getting gummed up, age-related mitochondrial mutations reducing the cells’ ability to generate energy, and our immune system slowly growing less efficient. Bones weaken, eyes strain, hearts flag. Bladders empty too often, bowels not often enough, and toxic proteins build up in the brain to form the plaque and the spaghetti-like tangles that are associated with Alzheimer’s disease. Not surprisingly, sixty-eight per cent of Medicare beneficiaries today have multiple chronic conditions. Not a lot of grace, force, or fascination in that.
In short, the optimistic narrative of pro-aging writers doesn’t line up with the dark story told by the human body. But maybe that’s not the point. “There is only one solution if old age is not to be an absurd parody of our former life,” Simone de Beauvoir wrote in her expansive 1970 study “The Coming of Age,” “and that is to go on pursuing ends that give our existence a meaning—devotion to individuals, to groups, or to causes—social, political, intellectual, or creative work.”
One would, of course, like to approach old age with grace and fortitude, but old age makes it difficult. Those who feel that it’s a welcome respite from the passions, anxieties, and troubles of youth or middle age are either very lucky or toweringly reasonable. Why rail against the inevitable—what good will it do? None at all. Complaining is both pointless and unseemly. Existence itself may be pointless and unseemly.
We should all make peace with aging. And so my hat is off to Dr. Oliver Sacks, who chose to regard old age as “a time of leisure and freedom, freed from the factitious urgencies of earlier days, free to explore whatever I wish, and to bind the thoughts and feelings of a lifetime together.”

Friday, November 08, 2019

World wide movement of people into cities is degrading the human microbiome

From the Oct. 25 issue of Science Magazine:
Sonnenburg and Sonnenburg review how the shift of recent generations from rural, outdoor environments to urbanized and industrialized settings has profoundly affected our biology and health. The signals of change are seen most strikingly in the reduction of commensal microbial taxa and loss of their metabolic functions. The extirpation of human commensals is a result of bombardment by new chemicals, foodstuffs, sanitation, and medical practices. For most people, sanitation and readily available food have been beneficial, but have we now reached a tipping point? How do we “conserve” our beneficial symbionts and keep the pathogens at bay?
Here is their abstract:
The human body is an ecosystem that is home to a complex array of microbes known as the microbiome or microbiota. This ecosystem plays an important role in human health, but as a result of recent lifestyle changes occurring around the planet, whole populations are seeing a major shift in their gut microbiota. Measures meant to kill or limit exposure to pathogenic microbes, such as antibiotics and sanitation, combined with other factors such as processed food, have had unintended consequences for the human microbial ecosystem, including changes that may be difficult to reverse. Microbiota alteration and the accompanying loss of certain functional attributes might result in the microbial communities of people living in industrialized societies being suboptimal for human health. As macroecologists, conservationists, and climate scientists race to document, understand, predict, and delay global changes in our wider environment, microbiota scientists may benefit by using analogous approaches to study and protect our intimate microbial ecosystems.

Wednesday, November 06, 2019

How human breeding has changed dogs’ brains

Hecht et al. have identified brain networks in dogs related to behavioral specializations roughly corresponding to sight hunting, scent hunting, guarding, and companionship. Here is their detailed abstract:
Humans have bred different lineages of domestic dogs for different tasks such as hunting, herding, guarding, or companionship. These behavioral differences must be the result of underlying neural differences, but surprisingly, this topic has gone largely unexplored. The current study examined whether and how selective breeding by humans has altered the gross organization of the brain in dogs. We assessed regional volumetric variation in MRI studies of 62 male and female dogs of 33 breeds. Neuroanatomical variation is plainly visible across breeds. This variation is distributed nonrandomly across the brain. A whole-brain, data-driven independent components analysis established that specific regional subnetworks covary significantly with each other. Variation in these networks is not simply the result of variation in total brain size, total body size, or skull shape. Furthermore, the anatomy of these networks correlates significantly with different behavioral specialization(s) such as sight hunting, scent hunting, guarding, and companionship. Importantly, a phylogenetic analysis revealed that most change has occurred in the terminal branches of the dog phylogenetic tree, indicating strong, recent selection in individual breeds. Together, these results establish that brain anatomy varies significantly in dogs, likely due to human-applied selection for behavior.

Monday, November 04, 2019

A triple drug combination increases lifespan by 48%

In Drosophila flies, to be sure, but the nutrient sensing pathways that are the target of the drugs are common to all animals. Here is the abstract from open source article by Castillo-!uan et al.:
Increasing life expectancy is causing the prevalence of age-related diseases to rise, and there is an urgent need for new strategies to improve health at older ages. Reduced activity of insulin/insulin-like growth factor signaling (IIS) and mechanistic target of rapamycin (mTOR) nutrient-sensing signaling network can extend lifespan and improve health during aging in diverse organisms. However, the extensive feedback in this network and adverse side effects of inhibition imply that simultaneous targeting of specific effectors in the network may most effectively combat the effects of aging. We show that the mitogen-activated protein kinase kinase (MEK) inhibitor trametinib, the mTOR complex 1 (mTORC1) inhibitor rapamycin, and the glycogen synthase kinase-3 (GSK-3) inhibitor lithium act additively to increase longevity in Drosophila. Remarkably, the triple drug combination increased lifespan by 48%. Furthermore, the combination of lithium with rapamycin cancelled the latter’s effects on lipid metabolism. In conclusion, a polypharmacology approach of combining established, prolongevity drug inhibitors of specific nodes may be the most effective way to target the nutrient-sensing network to improve late-life health.

Friday, November 01, 2019

Skill development - the intelligence vs. practice debate reframed

Vaci et al. note that what is often overlooked in the nature vs. nurture debate is the fact that both factors interact with each other:
The relative importance of different factors in the development of human skills has been extensively discussed. Research on expertise indicates that focused practice may be the sole determinant of skill, while intelligence researchers underline the relative importance of abilities at even the highest level of skill. There is indeed a large body of research that acknowledges the role of both factors in skill development and retention. It is, however, unknown how intelligence and practice come together to enable the acquisition and retention of complex skills across the life span. Instead of focusing on the 2 factors, intelligence and practice, in isolation, here we look at their interplay throughout development. In a longitudinal study that tracked chess players throughout their careers, we show that both intelligence and practice positively affect the acquisition and retention of chess skill. Importantly, the nonlinear interaction between the 2 factors revealed that more intelligent individuals benefited more from practice. With the same amount of practice, they acquired chess skill more quickly than less intelligent players, reached a higher peak performance, and arrested decline in older age. Our research demonstrates the futility of scrutinizing the relative importance of highly intertwined factors in human development.