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Study: Language (not geography) major force behind India’s gene flow
The study found that people who spoke the same language tended to be more closely related despite living far apart.
- Studies focusing on European genetics have found a strong correlation between geography and genetic variation.
- Looking toward India, a new study found a stronger correlation between gene variation and language as well as
- social structure.
- Understanding social and cultural influences can help expand our knowledge of gene flow through human history.
When we think about our ancestors, our minds tend to wander to geography. We introduce our progenitors by noting they were Norwegian, Brazilian, Indonesian, or members of an American Native tribe. Personal genetic tests, such as those offered by Ancestry and 23andMe, offer customers a travel log of their lineages' global journeys. And some of our more obvious phenotypic markers, such as hair and skin color, evolved in relationship with the lands our ancestors called home.
Lost within this land-locked focus is the fact that social and cultural factors—how our ancestors cohabitated and interacted with each other—also influence gene flow. In doing so, these factors shaped our evolution and genetic diversity. As a new study has found, for the peoples of the Indian subcontinent, such social and cultural factors may be more important to their genetic variation than the deserts, grasslands, and tropical forests between them.
A new kind of mother tongue
A map showing the locations of 33 Indian populations alongside plot graphs showing the relations between sociolinguistic groups and genetic structures.
The new study, published in Molecular Biology and Evolution, began when Aritra Bose, who earned his doctorate at Purdue in genetics and data science, was researching the close ties between genes and geography in Europe. Originally from Calcutta, India, Bose wondered if such a strong link would be true of his home country. He teamed up with Peristera Paschou, a population geneticist and associate professor of biological sciences at Purdue University, and Petros Drineas, associate head of Purdue's Department of Computer Science, to find out.
"Our genome carries the signature of our ancestors, and the genetic structure of modern populations has been shaped by the forces of evolution. What we are looking for is what led different groups of people to come together and what drove them apart," Paschou, who led the study with Drineas, said in a press release. "To understand the genetics of human populations, we created a model that allows us to consider jointly many different factors that may have shaped genetics."
The researchers developed a computer model called COGG (Correlation Optimization of Genetics and Geodemographics) to analyze population genetic substructure. They then feed COGG a dataset featuring 981 individuals from 90 Indian groups, further merging that with a dataset of 1,323 individuals from 50 Eurasian populations. The model crunched the numbers and found something surprising.
Studies looking at European populations have typically found a strong correlation between genotype and geography. As one National Geographic writer put it when discussing a study published in Nature: "The result was startling—the genetic and geopolitical maps of Europe overlap to a remarkable degree. On the two-dimensional genetic map, you can make out Italy's boot and the Iberian peninsula [sic] where Spain and Portugal sit. The Scandinavian countries appear in the right order and in the south-east, Cyprus sits distinctly off the 'coast' of Greece."
Such a confluence of the geo and the genome was not found in the India study; in fact, the analysis showed a weak correlation between genotype and geography. Instead, it was shared language that proved the major genetic link.
The researchers found that people who speak the same language were much more likely to be closely related, regardless of where they lived on the subcontinent. For example, their analysis showed that Indo-European and Dravidian speakers shared genetic drift with Europeans, while Tibeto-Burman speaking tribes shared it with East Asians.
Social structure also showed a stronger correlation than geography in their analysis. The researchers hypothesized this correlation originated from the social stratification imposed by India's caste system.
For several thousands of years, the caste system divided Hindus into hierarchical groups based on their karma (work) and dharma (duty). Marriage was strictly limited within one's caste, resulting in a long history of endogamy. Though the caste system was effectively expunged in 1950 by the Indian government, such endogamy held sway over Indian society long enough to have a powerful effect on the country's historic gene flow.
"Our results clearly show that endogamy and language families are pivotal in studying the genetic stratification of Indian populations," the researchers write in the study.
New dimensions for understanding ancestry
None of this is to say that geography played no part in the ancestral gene flow of India, nor that social and cultural factors didn't influence genotypes across Europe. They most certainly did. That Nature study, for example, discovered genetic clusters in Switzerland that were language-based. And Europe's geographic distribution may have more to do with historical sociopolitical realities than environmental ones.
The point of both studies, however, is not to tie our genetic history to land or language, but to understand how genes flowed throughout historical societies.
"It sheds light on how genetics work in our society," Bose said in the same release. "This is the first model that can take into account social, cultural, environmental and linguistic factors that shape the gene flow of populations. It helps us to understand what factors contribute to the genetic puzzle that is India. It disentangles the puzzle."
With an improved knowledge of historic gene flow, scientists may be able to further biomedical research to better detect rare genetic variants, assess individual risks to certain diseases, and predict which populations may be more or less susceptible to particular drugs. By opening the avenues we use to understand our genetic history, we can hopefully advance such knowledge and understanding.
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A new study finds that dogs fed fresh human-grade food don't need to eat—or do their business—as much.
- Most dogs eat a diet that's primarily kibble.
- When fed a fresh-food diet, however, they don't need to consume as much.
- Dogs on fresh-food diets have healthier gut biomes.
Four diets were tested<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NjY0NjIxMn0._w0k-qFOC86AqmtPHJBK_i-9F5oVyVYsYtUrdvfUxWQ/img.jpg?width=980" id="1b1e4" class="rm-shortcode" data-rm-shortcode-id="87937436a81c700a8ab3b1d763354843" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: AntonioDiaz/Adobe Stock<p>The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The <a href="https://frontierpets.com.au/blogs/news/how-kibble-or-dry-dog-food-is-made" target="_blank">ingredients</a> of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a <a href="https://en.wikipedia.org/wiki/Food_extrusion" target="_blank">pasta maker</a>. The resulting pellets are sprayed with additional flavor and color.</p><p>For four weeks, researchers fed 12 beagles one of four diets:</p><ol><li>a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe</li><li>a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe</li><li>a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe</li><li>another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.</li></ol><p>The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts. </p><p>(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)</p><p>Senior author <a href="https://ansc.illinois.edu/directory/ksswanso" target="_blank" rel="noopener noreferrer">Kelly S. Swanson</a> of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he <a href="https://aces.illinois.edu/news/feed-fido-fresh-human-grade-dog-food-scoop-less-poop" target="_blank">says</a>, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."</p>
Tracking the effect of each diet<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NjY1NTgyOX0.AdyMb8OEcjCD6iWYnXjToDmcnjfTSn-0-dfG96SIpUA/img.jpg?width=980" id="da892" class="rm-shortcode" data-rm-shortcode-id="880d952420679aeccd1eaf32b5339810" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: Patryk Kosmider/Adobe Stock<p>The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.</p><p>It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.</p><p>Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."</p><p>Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.</p><p>"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in <a href="https://academic.oup.com/jas/article/92/9/3781/4702209#110855647" target="_blank">previous studies</a>, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."</p>
How did kibble take over canine diets?<p>Historically, dogs ate scraps left over by humans. It has only been <a href="https://www.thefarmersdog.com/digest/the-history-of-commercial-pet-food-a-great-american-marketing-story/" target="_blank">since 1870</a>, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn <a href="https://www.dogfoodadvisor.com/choosing-dog-food/animal-by-products/" target="_blank">human-food waste</a> into profit.</p><p>Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are <a href="https://www.nytimes.com/2014/08/03/magazine/who-made-that-dog-biscuit.html" target="_blank">overweight or obese</a>, and certainly their diet is a factor.<span></span></p><p>We're not so special among animals after all. If something's healthy for us to eat—we're <em>not</em> looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.</p>
New study suggests the placebo effect can be as powerful as microdosing LSD.
- New research from Imperial College London investigated the psychological effects of microdosing LSD in 191 volunteers.
- While microdosers experienced beneficial mental health effects, the placebo group performed statistically similar to those who took LSD.
- Researchers believe the expectation of a trip could produce some of the same sensations as actually ingesting psychedelics.
Psychedelics: The scientific renaissance of mind-altering drugs<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="92360c805fe66c11de38a75b0967f417"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/5T0LmbWROKY?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>For the study published in eLife, the team recruited 191 citizen cosmonauts to microdose either LSD or a placebo over the course of several weeks and note the psychological effects. Volunteers were already microdosing LSD, so there was no true control. Each volunteer was given instructions on creating their own low-dose gel capsules, some containing LSD, others not. Then they mixed the capsules in envelopes so they didn't know if they were taking the real thing or not.</p><p>The trial design was ingenious: each capsule featured a QR code that was scanned after the addition of ingredients but before they were placed in the envelope so that researchers knew what they were ingesting.</p><p>The problem: volunteers sourced their own LSD. Lack of quality control could have had a profound effect on the results. </p><p>The results: LSD microdosers reported feeling more mindful, satisfied with life, and better overall; they also noticed a reduction in feelings of paranoia. </p><p>The catch: the control group felt the same thing, with no statistical difference between the groups. </p><p>Lead author Balázs Szigeti comments on the findings: "This suggests that the improvements may not be due to the pharmacological action of the drug but can instead be explained by the placebo effect." </p>
Credit: Alexander / Adobe Stock<p>Psychedelics are notoriously difficult to control for given the intensity of the experience. Yet there is precedent for the above findings. A <a href="https://link.springer.com/article/10.1007/s00213-020-05464-5" target="_blank">2019 study</a> found that 61 percent of volunteers that took a placebo instead of psilocybin felt some psychedelic effects, with a few volunteers experiencing full-on trips.</p><p style="margin-left: 20px;">"Several stated that they saw the paintings on the walls 'move' or 'reshape' themselves, others felt 'heavy. . . as if gravity [had] a stronger hold', and one had a 'come down' before another 'wave' hit her."</p><p>The Imperial team believes the expectation of a trip might have been enough to produce similar results. Senior author David Erritzoe is excited for future studies on the topic, believing they tapped into a new wave of citizen science that could push forward our knowledge of psychedelic substances.</p><p style="margin-left: 20px;">"Accounting for the placebo effect is important when assessing trends such as the use of cannabidiol oils, fad diets or supplements where social pressure or users' expectations can lead to a strong placebo response. Self-blinding citizen science initiatives could be used as an inexpensive, initial screening tool before launching expensive clinical studies."</p><p>As investments into the psychedelics market explode, with one company <a href="https://www.bloomberg.com/news/articles/2021-03-03/thiel-backed-magic-mushroom-firm-atai-hits-2-billion-valuation" target="_blank">reaching a $2 billion valuation</a>, a recurring irony appears in the long arc of psychedelics and research: the power of our minds might be enough to feel greater life satisfaction and a deeper sense of mindfulness. If that's possible with a placebo, we have to question why the rush to create more pharmacology is necessary. </p><p>This is, mind you, a separate conversation over the role of psychedelics and rituals for group bonding. The function of group cohesion around consciousness-altering substances will continue to play an important role in many communities. </p><p>Of course, we should continue to explore the efficacy of psychedelics on anxiety, depression, suicidal ideation, PTSD, and addiction. <a href="https://bigthink.com/surprising-science/antidepressant-effects" target="_self">Pharmacological dependence</a> is a stain on the psychiatry industry. Whether or not psychedelics can be prescribed for daily use remains to be seen, but we know a moneyed interest is expecting a return on investment—the above company, ATAI Life Sciences, raised $157 million in its Series D round. </p><p>When it comes to wellbeing, some things money just can't buy. How we navigate the tricky terrain of mainstreaming psychedelics remains to be seen. </p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a> and <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank" rel="noopener noreferrer">Facebook</a>. His most recent book is</em> "<em><a href="https://www.amazon.com/gp/product/B08KRVMP2M?pf_rd_r=MDJW43337675SZ0X00FH&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee" target="_blank" rel="noopener noreferrer">Hero's Dose: The Case For Psychedelics in Ritual and Therapy</a>."</em></p>
What makes some people more likely to shiver than others?
Some people just aren't bothered by the cold, no matter how low the temperature dips. And the reason for this may be in a person's genes.