Wired that way: genes do shape behaviors but it’s complicated
The relationship between our genotypes and our psychological traits, while substantial, is highly indirect and emergent.
Many of our psychological traits are innate in origin. There is overwhelming evidence from twin, family and general population studies that all manner of personality traits, as well as things such as intelligence, sexuality and risk of psychiatric disorders, are highly heritable. Put concretely, this means that a sizeable fraction of the population spread of values such as IQ scores or personality measures is attributable to genetic differences between people. The story of our lives most definitively does not start with a blank page.
But exactly how does our genetic heritage influence our psychological traits? Are there direct links from molecules to minds? Are there dedicated genetic and neural modules underlying various cognitive functions? What does it mean to say we have found 'genes for intelligence', or extraversion, or schizophrenia? This commonly used 'gene for X' construction is unfortunate in suggesting that such genes have a dedicated function: that it is their purpose to cause X. This is not the case at all. Interestingly, the confusion arises from a conflation of two very different meanings of the word 'gene'.
From the perspective of molecular biology, a gene is a stretch of DNA that codes for a specific protein. So there is a gene for the protein haemoglobin, which carries oxygen around in the blood, and a gene for insulin, which regulates our blood sugar, and genes for metabolic enzymes and neurotransmitter receptors and antibodies, and so on; we have a total of about 20,000 genes defined in this way. It is right to think of the purpose of these genes as encoding those proteins with those cellular or physiological functions.
But from the point of view of heredity, a gene is some physical unit that can be passed from parent to offspring that is associated with some trait or condition. There is a gene for sickle-cell anaemia, for example, that explains how the disease runs in families. The key idea linking these two different concepts of the gene is variation: the 'gene' for sickle-cell anaemia is really just a mutation or change in sequence in the stretch of DNA that codes for haemoglobin. That mutation does not have a purpose – it only has an effect.
So, when we talk about genes for intelligence, say, what we really mean is genetic variants that cause differences in intelligence. These might be having their effects in highly indirect ways. Though we all share a human genome, with a common plan for making a human body and a human brain, wired so as to confer our general human nature, genetic variation in that plan arises inevitably, as errors creep in each time DNA is copied to make new sperm and egg cells. The accumulated genetic variation leads to variation in how our brains develop and function, and ultimately to variation in our individual natures.
This is not metaphorical. We can directly see the effects of genetic variation on our brains. Neuroimaging technologies reveal extensive individual differences in the size of various parts of the brain, including functionally defined areas of the cerebral cortex. They reveal how these areas are laid out and interconnected, and the pathways by which they are activated and communicate with each other under different conditions. All these parameters are at least partly heritable – some highly so.
That said, the relationship between these kinds of neural properties and psychological traits is far from simple. There is a long history of searching for correlations between isolated parameters of brain structure – or function – and specific behavioural traits, and certainly no shortage of apparently positive associations in the published literature. But for the most part, these have not held up to further scrutiny.
It turns out that the brain is simply not so modular: even quite specific cognitive functions rely not on isolated areas but on interconnected brain subsystems. And the high-level properties that we recognise as stable psychological traits cannot even be linked to the functioning of specific subsystems, but emerge instead from the interplay between them.
Intelligence, for example, is not linked to any localised brain parameter. It correlates instead with overall brain size and with global parameters of white matter connectivity and the efficiency of brain networks. There is no one bit of the brain that you do your thinking with. Rather than being tied to the function of one component, intelligence seems to reflect instead the interactions between many different components – more like the way we think of the overall performance of a car than, say, horsepower or braking efficiency.
This lack of discrete modularity is also true at the genetic level. A large number of genetic variants that are common in the population have now been associated with intelligence. Each of these by itself has only a tiny effect, but collectively they account for about 10 per cent of the variance in intelligence across the studied population. Remarkably, many of the genes affected by these genetic variants encode proteins with functions in brain development. This didn't have to be the case – it might have turned out that intelligence was linked to some specific neurotransmitter pathway, or to the metabolic efficiency of neurons or some other direct molecular parameter. Instead, it appears to reflect much more generally how well the brain is put together.
The effects of genetic variation on other cognitive and behavioural traits are similarly indirect and emergent. They are also, typically, not very specific. The vast majority of the genes that direct the processes of neural development are multitaskers: they are involved in diverse cellular processes in many different brain regions. In addition, because cellular systems are all highly interdependent, any given cellular process will also be affected indirectly by genetic variation affecting many other proteins with diverse functions. The effects of any individual genetic variant are thus rarely restricted to just one part of the brain or one cognitive function or one psychological trait.
What all this means is that we should not expect the discovery of genetic variants affecting a given psychological trait to directly highlight the hypothetical molecular underpinnings of the affected cognitive functions. In fact, it is an error to think of cognitive functions or mental states as having molecular underpinnings – they have neural underpinnings.
The relationship between our genotypes and our psychological traits, while substantial, is highly indirect and emergent. It involves the interplay of the effects of thousands of genetic variants, realised through the complex processes of development, ultimately giving rise to variation in many parameters of brain structure and function, which, collectively, impinge on the high-level cognitive and behavioural functions that underpin individual differences in our psychology.
And that's just the way things are. Nature is under no obligation to make things simple for us. When we open the lid of the black box, we should not expect to see lots of neatly separated smaller black boxes inside – it's a mess in there.
Innate: How the Wiring of our Brains Shapes Who We Are by Kevin Mitchell is published via Princeton University Press.
This article was originally published at Aeon and has been republished under Creative Commons.
Researchers documented the most common negative side effects of smoking weed, and who might be most susceptible.
- A team of researchers identified a total of 26 possible adverse reactions to cannabis use.
- Coughing fits, anxiety, and paranoia are among the top three most common adverse reactions to smoking weed.
- It was the people who smoke on a less frequent basis who were more likely to have had the bad experiences.
The most common adverse effects of pot<p>As it turns out, coughing fits are among the top three most common adverse reactions to cannabis use, along with anxiety and paranoia, according to a new study published in the <em>Journal</em><a href="https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-019-0013-x" target="_blank"><em> of Cannabis Research</em></a>. </p><p>Now that weed is legal in the state, a team of researchers at Washington State University sought to document potential negative reactions to cannabis in order to paint a detailed picture of the effects of smoking weed for newbies. The authors surveyed more than 1,500 college students on the specific type and frequency of adverse reactions they had experienced while using pot. Additionally, the students in the study were surveyed about their demographics, personality traits, reasons for using cannabis and their use patterns. </p><p>Despite marijuana's <a href="https://bigthink.com/sex-relationships/marijuana-sex" target="_self">numerous benefits</a>, the team identified a total of <a href="https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-019-0013-x/tables/2" target="_blank">26 possible adverse reactions to</a> the drug. More than half of the study participants reported having coughing fits along with anxiety and/or paranoia while using cannabis. The most frequently occuring of these were the coughing fits, along with chest/lung discomfort and body humming. A subset of the study group reported these reactions occurring around 30–40% of the time they were using pot. On the flip side, the three <em>least</em>-commonly reported reactions to cannabis use were fainting, visual hallucinations and cold sweats. </p><p>"There's been surprisingly little research on the prevalence or frequency of various adverse reactions to cannabis and almost no research trying to predict who is more likely to experience these types of adverse reactions," <a href="https://news.wsu.edu/2020/03/30/new-research-sheds-light-potentially-negative-effects-cannabis/" target="_blank">said Carrie Cuttler</a>, assistant professor of psychology and an author on the paper, according to WSU News. "With the legalization of cannabis in Washington and 10 other states, we thought it would be important to document some of this information so that more novice users would have a better sense of what types of adverse reactions they may experience if they use cannabis."</p><p>The most distressing of the 26 negative reactions were panic attacks, fainting, and vomiting. Yet, the survey data suggested that cannabis users generally do not find even acute adverse reactions to cannabis to be severely distressing.</p>
What causes a bad reaction?<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwOTEwOC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNTQ5MDQ2Mn0.S2Pkbh3VAgB4Gk5tkavamMv0_4t76dg65yGWpCHG17U/img.jpg?width=1245&coordinates=0%2C1872%2C0%2C1252&height=700" id="dee45" class="rm-shortcode" data-rm-shortcode-id="df6e30ecae156ba0012f4773a374800c" data-rm-shortcode-name="rebelmouse-image" />
But most city dwellers weren't seeing the science — they were seeing something out of Blade Runner.
On Sept. 9, many West Coast residents looked out their windows and witnessed a post-apocalyptic landscape: silhouetted cars, buildings and people bathed in an overpowering orange light that looked like a jacked-up sunset.
India finishes last of 60 countries in environment and sustainability, as ranked by the expats who work there.
- How 'green' is life in your work country?
- That's the question InterNations asked its network of expats.
- The United States ended 30th out of 60 countries.
Nordics on top<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2NjgyNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NTczNzkyOX0.VgfqyjAa9avw6gFOE0qlgSgKuBN7DJmzOc5lzFGLm8g/img.jpg?width=980" id="1f0dc" class="rm-shortcode" data-rm-shortcode-id="b27458cf472d26cf1f87cb91623a0621" data-rm-shortcode-name="rebelmouse-image" alt="Evo Hiking Area, H\u00e4meenlinna, Finland." />
Evo Hiking Area in Hämeenlinna, Finland. Great nature, clean air, clean water? Check, check and check.
Credit: Kanta-Hämeen kuvapankki on Flickr/ Public Domain.<p><br><strong>1. Finland</strong></p><p>The Nordic country scores at or near the top in all categories surveyed, including the quality of the natural environment (say 96 percent of expats in Finland), water and sanitation (96 percent) and air (95 percent). <br></p><p><strong>2. Sweden</strong></p><p>Swedes lead the world in environmental awareness (84 percent versus just 48 percent globally). Perhaps not surprising, for the homeland of <a href="https://bigthink.com/politics-current-affairs/greta-effect" target="_blank">Greta Thunberg</a>. This is reflected by government policy. Sweden currently gets more than 50 percent of its power from renewable sources and wants to go 100% renewable before 2040. "I've been here for over 20 years and I clearly see the benefits of my taxes paid coming back to me and the rest of society," says one American expat.<br></p><p><strong>3. Norway</strong></p><p>"The beautiful nature, the clean air and tap water, and the focus on the environment," are what one Ukrainian expat enjoys most about Norway. With 76 percent of expats happy with the availability of green goods and services, Norway's 'weakest' category is still 13 percentage points above the global average. <br></p><p><strong>4. Austria</strong></p><p>The first non-Nordic in the global ranking, Austria places in the Top 10 for each category and comes in first for the availability of green goods and services (90 percent). <br></p><p><strong>5. Switzerland</strong></p><p>Swiss nature is the most appreciated in the world (98 percent versus 83 percent on average). Switzerland also gets stellar results for air and water quality and the availability of green energy and green goods and services. </p><p><strong>6. Denmark</strong></p><p>Danes are very much into green causes, as is their government, say 83 percent resp. 84 percent of expats. "Organic food is readily available, and they are good with recycling," observes a South African expat. And they love cycling: 9 out of 10 Danes own a bike.</p><p><strong>7. New Zealand</strong></p><p>85 percent of expats agree that the New Zealand government takes green issues seriously. In fact, New Zealand plans to use 90 percent electricity from renewables by 2025. The country also scores high on the quality of its natural environment and all other categories – albeit slightly less on the quality of its water and sanitation.</p><p><strong>8. Germany</strong></p><p>"I enjoy the rising awareness about environmental issues and the alternatives the government and society are developing," says one Colombian expat. Indeed, 80 percent of expats agree the German government is pro-environment (versus 55 percent globally). <br></p><p><strong>9. Canada</strong></p><p>The only North American destination in the Top 10, thanks especially to expat appreciation of Canada's natural environment (96 percent), but also the quality of its water and sanitation (90 percet) and the availability of green goods and services (80 percent). <br></p><p><strong>10. Luxembourg</strong></p><p>"Access to nature for hiking and bicycling" is a definite boon for one American expat. In fact, the country's natural environment, although ranking 13th out of 60, is its lowest-rated subcategory. Luxembourg does even better when it comes to green energy, waste management, and the quality of its air and water.</p>
Taiwan, most sustainable destination in Asia<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2Njg1Ni9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NzkxMDAxNH0.Roy7h_Od1cmaqBmamk-DP4rKMpLjTM-qIajG96alZAg/img.jpg?width=980" id="00799" class="rm-shortcode" data-rm-shortcode-id="dab52370e1edb5da5ebb0f5631027b1c" data-rm-shortcode-name="rebelmouse-image" alt="\u200bEternal Spring Shrine in the Taroko Gorge, Hualien County, Taiwan." />
Eternal Spring Shrine in the Taroko Gorge, Hualien County. Outside of Taipei, Taiwan can be surprisingly green and beautiful.
Credit: Zairon, CC BY-SA 4.0<p><strong>11. Taiwan</strong></p><p>The highest-scoring expat destination in Asia, Taiwan boasts 92 percent approval of its waste management and recycling, and 80 percent of the availability of green goods and services. But "the air pollution (in Taipei) is getting worse because it is too crowded," one expat complains.</p><p><strong>12. Netherlands</strong></p><p>Green goods and services are widely available, agree 82 percen of expats, as is green energy. However, 13 percent rate the Dutch environment negatively, 4 percet above the global average. <br></p><p><strong>13. Portugal</strong></p><p>Well ahead of its neighbor Spain (#20), the country scores high for air quality (91 percent) and natural environment (95 percent). "I like the opportunity for gardening and growing our own food," says one expat. <br></p><p><strong>14. Estonia</strong></p><p><strong></strong>Estonia scores in the Top 20 for every category and gets its highest marks for its natural environment. "A beautiful country with excellent air quality and open spaces," praises an Indian expat.<br></p><p><strong>15. Costa Rica</strong></p><p><strong></strong>Both the government and the people are very supportive of green policies, find 82 percent, resp. 67 percent of expats. "It's easy to live a healthy lifestyle with regard to the food, climate, clean air and water," says one. Costa Rica won the 2019 UN Champion of the Earth award and has pledged to go carbon neutral by 2050.<br></p><p><strong>16. Czechia</strong></p><p><strong></strong>"The beauty of the environment" is one of the best things about living in Czechia, says a Russian expat. No less than 97 percent of expats agree.<br></p><p><strong>17. France</strong></p><p><strong></strong>77 percent of expats are happy about the availability of green goods and services in France, which is 14 percentage points above average. The country also scores well for waste management and recycling. In short, France has a "good, green and clean environment," one Iranian expat finds. <strong><br></strong></p><p><strong>18. Australia</strong></p><p><strong></strong>While ranking high on the quality of its nature, water and air, Australia scores low when it comes to government support for green issues (51 percent). Fortunately, expats see more interest among the general population (68 percent). </p><p><strong>19. Singapore</strong></p><p><strong></strong>Expats rate the government's interest in green issues higher than globally average (77 percent versus 55 percent), but the Singaporean public's engagement for the same less than average (40 percent versus 48 percent). Of course, in a small, crowded place like Singapore, "(nature) spots are limited."<br></p><p><strong>20. Spain</strong></p><p>Spain's "scenery, diversity of places to visit and healthier environment" are what rate highly with one British expat. Its weak point is governmental and public support for green issues – but still slightly above the global average. <br></p>
London is "polluted and noisy"<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2Njg4Ni9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NDg3NjkyOH0.3ySSD7jFBfAWA07u-EN-oL9x9cq9FZn06iz5aV0hEOw/img.jpg?width=980" id="f5630" class="rm-shortcode" data-rm-shortcode-id="80c9fa119e7ff3acc91e027b7529bfed" data-rm-shortcode-name="rebelmouse-image" alt="\u200bEven at 2:30pm, London gets clogged." />
Afternoon traffic jam in London.
World map for the 'sustainable expat'<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2Njg5MC9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYzMzAyNjQ2MH0.hjRiMDmOSnn9EvKJtx_tlzql3Gf7ph8lt8bL6dPCft4/img.png?width=980" id="def5d" class="rm-shortcode" data-rm-shortcode-id="149be2f5a19cc625cb555d8078f62ce2" data-rm-shortcode-name="rebelmouse-image" alt="The best & worst destiations for the sustainable expat" />
Sixty expat destinations ranked for sustainability, from best (orange) to worst (light blue). In between: fairly okay (brown), middling (grey) and not that great (dark blue).
South Korea's "rather horrible" air<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2NjkxNS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MTY1MjIwNn0.2e6eBIc38sAZLFQGKw4UL3-SY3hA9NthX0Uj9L4ibZA/img.jpg?width=980" id="c10db" class="rm-shortcode" data-rm-shortcode-id="cba918e6e5455c2e5ff4f9d5caf54775" data-rm-shortcode-name="rebelmouse-image" alt="\u200bSmoggy Seoul" />
Seoul's air quality is so bad you can picture it. Only India's air is perceived as worse than South Korea's, according to the expat survey.
Bad, worse, India<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2Njk0MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NTcyMTczMH0.Pt2bGDrpSKSwVjimMK_iK0Jejpu8ILn77VEzHTdzQQ4/img.jpg?width=980" id="28411" class="rm-shortcode" data-rm-shortcode-id="8b8b602261a168a46b05c53e09ab1b02" data-rm-shortcode-name="rebelmouse-image" alt="man standing surrounded by garbage" />
India scores worst in all three categories, but to be fair – some of its problems were imported from more developed countries.