Taking a Break

I'm going to take a break from this blog for a while. I honestly don't know whether or not I'll come back to it, but I think it's done its job for me for now. The articles I've explored so far give a pretty good idea of the breadth of my interest and comprehension, at least along the lines of empirical research. 

The most challenging aspect is finding articles I want to approach this way, especially for the more human-centered fields. I think maybe with natural science I'm perfectly happy looking at how this or that specific organism reacts to this or that specific situation, but with human-centered fields, I'm more interested in theories with broader strokes that don't lend themselves so well to this kind of blog. At the same time, I do feel like more research is needed, but maybe the kind of research I'm interested in isn't being done. 

This could be a demand-avoidance thing, but I feel like much of the research on humans carries a bit of prescriptivism - a sense of let's see how to make people have the outcomes we want. Sort of along the lines of if people aren't prioritizing what we think they should prioritize, how do we change that, instead of how do we help people do what they themselves want, even if that's something that changes? And I'm not necessarily saying that kind of research doesn't exist, but it's hard to find. 

I'm trying to make a career change, and part of my idea was that this blog would be good practice and would showcase some of what I can do. That's true as far as it goes, but I think my intrinsic motivation has run out for now - I think I'd be happy to do this kind of work for pay, but as a hobby, it's starting to feel too much like an obligation. Thanks to everyone that's taken the time to read over the past several months! 

Liu, Jing, Yun‐Heng Miao, Hong‐Xia Hou, Da‐Wei Huang, and Jin‐Hua Xiao. "Ecological Niche Adaptations Influence Transposable Element Dynamics in Pollinating and Non‐Pollinating Fig Wasps." Ecology and Evolution 15, no. 6 (2025): e71553.

 

What They Did

The researchers examined the DNA of 11 species of fig wasps, 6 fig pollinators and 5 non-pollinators. The pollinating species enter the synocium (the structure that completely encloses the flowers and, later, the tiny multiple fruits), while the non-pollinating species pierce the synocium with their ovipositors to lay eggs. The researchers particularly looked at the transposable elements, segments of DNA that can move from one area of the genome to another. They found that the non-pollinating wasps had significantly more transposable content in their genomes and that the individual transposable elements of the pollinating wasps were shorter.

They compared the genetics of the different species to develop a phylogeny, which shows that the pollinating wasps form a clade that diverged from the non-pollinating wasps. Based on the differences among transposable elements and the background mutation rate, they determined that the transposable elements in the pollinating wasps were 10 to 30 million years old, while the those of the non-pollinating wasps were less than 5 million years old.

In addition, the pollinator wasp species have smaller effective population sizes: a less varied population has a smaller effective population size than a more varied population with the same number of individuals. The researchers suggest that since the pollinating wasps spend most of their lives in the stable, enclosed environment of the fig synocium, the selection pressures tend towards conservation of the well-adapted phenotype. The non-pollinating wasps, in contrast, encounter more varied environments, such that more genetic variability is likely to be adaptive.

Further Exploration

Transposable elements (also called transposons) are fascinating and difficult to understand. There are two major types: one type (Type I) gets copied and pasted elsewhere in the genome, but the original copy remains. The other type (Type II) gets cut and pasted, moving from one location to another.

In Type I, the transposon DNA is transcribed into RNA and then reverse transcribed back into DNA. Repeating sequences of bases determine where the new DNA can be integrated into the genome with the help of enzymes. The Type II transposons, meanwhile, are not copied into RNA. Instead, both strands of DNA are enzymatically cut and held together, then moved elsewhere in the genome (see https://www.integra-biosciences.com/united-states/en/blog/article/transposons-jumping-genes-revolutionizing-genetics).

Of course, no discussion of transposons is complete without a mention of Barbara McClintock. By observing the variegated color patterns of corn, she realized that something other than mutation or Mendelian genetics must be responsible for the changes from one generation to the next. Her ideas were dismissed for decades, but she won the Nobel Prize for her work in 1983. (see https://www.nobelprize.org/stories/women-who-changed-science/barbara-mcclintock/). If a particular transposon is near the gene that codes for pigment in a corn cell, it stops pigmentation from occurring, but if it’s farther away, it has no effect. Since the location of the transposon can vary among cells within a kernel, the kernel ends up with a mottled pattern (see https://www.waynesword.net/transpos.htm). It would be interesting to learn how transposons may have evolved in the first place, but that’s a rabbit hole for another day! 

 

Image credit: Alandmanson

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Price, A., Sumner, P., & Powell, G. (2025). The subtypes of visual hypersensitivity are transdiagnostic across neurodivergence, neurology and mental health. Vision Research, 234, 108640.

What They Did

The researchers recruited participants to complete an online questionnaire about four areas of visual hypersensitivity: brightness, strobing, pattern (such as stripes), and intense visual environments (such as supermarkets). Participants were also asked to indicate any neurodivergent, medical, or mental health conditions. Nearly 2600 participants were included in the final data set.

Using the Hierarchical Taxonomy of Psychopathology, some conditions were combined for analysis: binge eating disorder, anorexia, and bulimia were combined into eating pathologies; social anxiety, OCD, panic disorder, and agoraphobia were considered as fear-based conditions; and depression, generalized anxiety disorder, PTSD, and borderline personality disorder were combined into distress-based conditions. ADHD, autism, dyslexia, dyspraxia, fibromyalgia, migraine, persistent postural-perceptual dizziness (PPPD), and synesthesia were also included. The researchers found that all 11 conditions or categories of conditions were associated with all for types of visual hypersensitivity.

Sensitivity to intense visual environments (IVE) was the most increased factor for people with ADHD, autism, dyslexia, fibromyalgia, and PPPD. People with dyspraxia also showed the largest increase in IVE sensitivity, as well as a greater sensitivity to pattern compared to brightness or strobing. People with migraines, synesthesia, eating pathologies, and conditions based on fear or distress had relatively little difference in the four types of sensitivity. Of these, people with migraines or synesthesia were most sensitive to pattern and the others were most sensitive to IVE. The researchers note that the lack of distinctive patterns may indicate that all these conditions share a broad visual hypersensitivity in addition to their widely varying symptoms.

Further Exploration

Since comorbidities are common, many of the participants had more than one condition and were included in the analysis for each. The researchers also statistically isolated the conditions to determine which visual hypersensitivities were the most predictive of each condition. For example, none of the hypersensitivities were significantly predictive of dyspraxia, while all four were predictive of autism. Therefore, the sensitivities to IVE and pattern among people with dyspraxia might result from the fact that many of those people are also autistic.

The researchers caution, however, that while isolating the conditions in this way may have benefits for better understanding the effect of each condition, it also risks erasing the lived experience of people with comorbidities. The point I found particularly interesting is that the researchers can only isolate the collections of symptoms that have their own names. Our understanding of many of these conditions is still very new, and we don’t really know how well our current conceptualizations actually reflect the underlying physiology.

Less than 100 years ago, autism was understood as a form of schizophrenia that manifested in childhood (see https://azaunited.org/blog/how-the-autism-diagnosis-has-evolved-over-time). By contrast, insulin for management of diabetes has been known since the 1920s (see https://origins.osu.edu/read/first-insulin-injection-treatment-diabetes). Fibromyalgia, meanwhile, was only officially recognized as a distinct medical condition in 1981 (see https://www.swing.care/blog/what-is-fibromyalgia/). It’s easy sometimes to forget how little we actually know. It would be really interesting to do a factor analysis on neurodivergence like the one used to develop the five-factor personality model, but that’s a rabbit hole for another day!

 

 Image credit: Frankie Fouganthin

https://commons.wikimedia.org/wiki/File:Supermarket_shelves.jpg 

Perrault, Charlotte, Miguel Baltazar‐Soares, Chiara Morosinotto, Patrik Karell, Karel Poprach, Lars‐Ove Nilsson, Daniel Eriksson et al. "Dressed for the Weather: Tawny Owl Feather Adaptations Across a Climatic Gradient." Ecology and Evolution 15, no. 6 (2025): e71441.

 What They Did

The researchers collected tawny owl (Strix aluco) feathers from nine populations throughout Europe and analyzed the degree to which feather traits varied by population and by climate. They found that the length of the plumulaceous portion (the fluffy part at the base) of feathers from the owls’ backs was inversely correlated with winter temperatures: the colder it was, the longer the plumulaceous part of the feathers. This finding did not hold for feathers on the front of the body. The researchers hypothesize that the insulating function is more important on the back because of the position of the lungs and because the front of the body has more insulating fat deposits.

They also obtained DNA samples from some of the owls in order to compare the differences in microsatellites (repeated sequences of DNA that are usually non-coding) among the populations; this give an estimate of the amount of divergence expected through genetic drift. When comparing the differences in feather traits to the microsatellite differences, the researchers found that the density of feather barbs varied among populations for the front feathers but not the back feathers. The density of barbules varied for both front and black feathers, as did the length of the plumulaceous portion of both front and back feathers.

Although all these traits varied among populations, only the length of the plumulaceous part of the back feathers was directly correlated with climate variables. The other variations may reflect adaptation to some other aspect of the environment for each population.

Further Exploration

Feathers have kind of a fractal structure: the rigid shaft of the feather, called the rachis, has barbs growing off perpendicular to it. The barbs are what you see if you gently pull apart a feather. Each barb has barbules growing off, perpendicular to the barb, so parallel to the rachis. The barbules interlock to keep the whole feather together. (see https://academy.allaboutbirds.org/feathers-article/).

The linked article also discusses the hypothesized steps in the evolution of feathers, from simple hollow tubes (that’s why we can put ink in them for quill pens!) to fuzzy barbs all attached at the base. The ends of the barbs eventually grew together to form a longer rachis, and the barbs also developed barbules. Finally, the barbules evolved the hook structure that holds the feather together, and feathers began developing different shapes for different purposes.

What did they evolve from? It can look like feathers replaced scales as non-avian dinosaurs evolved into birds, but a feather isn’t just a modified scale. Feathers and scales are entirely different structures that develop from the same type of thickened skin regions in the embryo. (see https://evolutionnews.org/2023/05/fossil-friday-a-dinosaur-feather-and-an-overhyped-new-study-on-the-origin-of-feathers/). The linked article also notes that the scales on bird feet are more chemically similar to bird feathers than to the scales of other reptiles, suggesting that sometime after feathers had evolved, scales re-evolved in birds. It would be interesting to look into the specific genetic and biochemical pathways that allow scales and feathers to develop in embryos, but that’s a rabbit hole for another day!

 

Image credit: Peter Trimming

https://commons.wikimedia.org/wiki/File:Tawny_Owl_%285946073610%29.jpg 

Yin, Z., Xuan, B., Zhang, X., & Di, Y. (2025). The transactional relationship between perceived stress and executive function among Chinese adolescents. Current Psychology, 1-12.

 What They Did

The researchers collected survey data from 320 Chinese high school students aged 15 to 18 years in June, September, and December of 2023. The surveys consisted of 14 questions on perceived stress and 21 on executive function: 6 questions on inhibitory control (i.e. resisting temptations and distractions), 8 on cognitive flexibility (i.e. adapting mentally to changes in tasks or circumstances), and 7 on working memory.

They found that perceived stress scores at the three timepoints were significantly correlated, as were executive function scores. Furthermore, stress and executive function were negatively correlated at each timepoint, perceived stress at one timepoint negatively predicted executive function at the next, and vice versa. For example, higher perceived stress in June predicted lower executive function in September, and lower executive function in September predicted higher perceived stress in December.

The same type of relationship held between perceived stress and cognitive flexibility and between perceived stress and inhibitory control, though with lower significance and smaller effect sizes for the stress/inhibitory control relationship. The relationship between perceived stress and working memory was similar, but working memory in September was not significantly related to stress in December, although working memory in June was negatively correlated with perceived stress in September. The authors suggest that the relationship between perceived stress and executive function can result in a vicious cycle in which students who are stressed have lower executive function and struggle more with their schoolwork, which can then result in more stress, leading to even more executive function difficulty.

Further Exploration

It makes intuitive sense that each of the components of executive function might affect and be affected by stress. Self-control is definitely harder when stressed: people recovering from addiction are encouraged to make sure they don’t get too hungry, angry, lonely, or tired (see https://health.clevelandclinic.org/halt-hungry-angry-lonely-tired) because those stressors make it harder to resist the urge to use.

From my experience, feeling stressed can also cause a sort of tunnel vision, making it more difficult to switch tasks or adapt to change. And of course, forgetting things while stressed is common, though this might be more of a general effect than an effect on working memory specifically. I can also see how difficulties with executive function might result in more stress, either because of mistakes resulting from poor executive function or because of overwhelm when faced with tasks one doesn’t have the capacities to handle.

The researchers also noted that Eastern educational systems are typically more competitive and higher pressure than many Western programs. They suggest that students would benefit from more engaging and exploratory schoolwork rather than rote memorization and high-stakes testing. The United States also has a lot of controversy around high-stakes testing (see https://www.idra.org/resource-center/the-dangerous-consequences-of-high-stakes-testing/) and academic rigor (see https://www.edweek.org/teaching-learning/opinion-academic-rigor-is-in-decline-a-college-professor-reflects-on-ap-scores/2024/10). There are many concerns around equity, practical sustainability, importance of education compared to other activities, and long-term mastery compared to short-term memorization. Figuring out how to provide the best education that’s available to everyone and balances learning with other needs is a huge project, but that’s a rabbit hole for another day!

 

Image credit: Kychn

https://commons.wikimedia.org/wiki/File:A_view_of_a_classroom_in_Tieling_High_School_02.jpg 

van't Veen, Hanneke, Koen Kuipers, Aafke Schipper, Alexandra Marques, Mart‐Jan Schelhaas, and Rob Alkemade. "A Global Assessment of Plant and Animal Community Responses to Forest Management Over Time." Global Change Biology 31, no. 6 (2025): e70279.

 What They Did

The researchers used global databases to examine the effects of forest management systems on animal and plant biodiversity. The data used compared the abundance of individual plant and animal species in managed forests and unmanaged reference forest sites. The biodiversity metrics used were: intactness (how much the abundance of each species at the reference site matches the managed site), similarity (the degree to which the managed and reference sites have the same species), relative species richness (a comparison between the number of species in the managed and reference sites), and relative total abundance (a comparison between the abundance of each species found in managed or reference sites).

They found that reduced-impact logging (harvesting a few trees with the intention of preserving biodiversity while acquiring wood resources) had the least impact on intactness. Both the intactness and the similarity of species between the managed and reference sites were lowest for plantations of perennial trees, such as oil palms, for food production. Selective cutting, clear cutting followed by regrowth, and agroforestry (growing food crops beneath a forest canopy) did not affect total species richness for plants or animals, though the species abundance changed. Timber plantations had a lower total relative abundance of animal species.

By comparing managed sites with different amounts of time since harvest (for logging) or establishment (for plantations and agroforestry), the researchers found that intactness and similarity to reference sites increased over time for selective cutting systems, timber plantations, and agroforestry systems and declined over time after clear cutting.

Further Exploration

One of the major results of the study was that intactness of the forest was significantly affected even with reduced-impact logging. On one hand, it makes sense that any amount of forest disruption, whether by removing trees, planting different species, or disturbing the space with machines, will have an impact. On the other hand, it shows the difficulty of ecological problems. Human activity always affects other species, even when we try to minimize our impact. Of course, this is true to varying degrees for all species: predators affect prey, parasites affect hosts, and “ecosystem engineer” species like beavers change the landscape.

Humans are different partly because of the size of our impact and partly because we can reflect and potentially make choices about it. Besides the questions of our physical dependence on other species, we also get to decide how much we value them for their own sake. Do we want just enough biodiversity to maximize the number of humans living healthy and fulfilled lives or do we want room for species that don’t affect our physical well-being? Can we have fulfilled lives in a world where all species are managed for human benefit?

These questions assume a degree of knowledge and skill at ecosystem management that we’re nowhere near achieving, but the more understanding we gain, the more relevant they become. I wonder what kind of personal and cultural traits will allow people to be happiest in the world we’re transforming, but that’s a rabbit hole for another day!

 

Image credit: Marco Schmidt

https://commons.wikimedia.org/wiki/File:Faidherbia_albida.JPG 

Senée, Pierre, Léa Krafft, Inès Loukili, Daniela Castro Farias, Olivier Thouvenin, Michael Atlan, Michel Paques, Serge Meimon, and Pedro Mecê. "Revealing neurovascular coupling at a high spatial and temporal resolution in the living human retina." Science Advances 11, no. 26 (2025): eadx2941.

 What They Did

The researchers developed an imaging system for real-time data collection on the diameter of retinal blood vessels. Using this system, they measured the diameter change of an artery providing blood to part of the retina that experienced a 10-Hz flickering light for 20 seconds. The eight participants all showed a significant widening of the relevant artery in response to the flicker.

After a short reaction time, the artery quickly dilates for about 7.7 seconds. The dilation then slows down but continues at the slower rate for about another 13 seconds until the artery reaches its largest diameter. When the flickering ceases, the artery quickly contracts, returning to baseline in about 9 seconds. The researchers also found that the percentage increase in dilation was inversely correlated with the diameter of the artery: larger arteries had a lower percent increase, though all had about the same absolute increase of 3.7 µm. The larger arteries also dilated more slowly.

Finally, the researchers observed the dilation response of a single participant with the flicker duration ranging from 2 to 60 seconds. If the flicker only lasts for 2 seconds, the artery dilates quickly, but it still takes 6 to 7 seconds, longer than the flicker persists. After reaching a peak diameter, the artery immediately begins to contract at a similar rate. With a 60-second flicker, the artery shows the fast and slow dilation processes as in the 20-second condition, but after peaking, it shows pulses of partial contraction and re-dilation approximately every 20 seconds.

Further Exploration

The researchers explain that the correlation between blood flow to and activation of specific parts of the brain or nervous system is well-documented and used in neurological research: for example, it’s the mechanism behind fMRI studies. They also explain that various medical conditions can disrupt that connection, which means parts the brain or nervous system might not get the oxygen they need for various tasks. (see https://www.cognitivefxusa.com/neurovascular-coupling).

The retina is part of the central nervous system: it literally forms out of brain tissue during embryonic development (see https://www.ncbi.nlm.nih.gov/books/NBK10885/). Because we can get higher-resolution imagery with light than with fMRI, looking at the correlation between activation and blood flow in specific areas of the retina might be a way to screen for some medical problems before they become detectable with fMRI.

The new imaging system the researchers developed works by illuminating the area step-by-step with a linear light source, then having pictures taken with a camera “in front of” and “behind” the illuminated area. The light waves from the two locations are out of phase, and the amount of phase difference varies depending on how easily light moves through areas such as blood vessels. Mapping the amount of phase difference to the region of the retina observed allows for images to be generated. The researchers indicate that other retinal imaging technologies also use phase contrast, but their system allows a larger area and a higher frame rate. I’d like to understand more about how it works, but that’s a rabbit hole for another day!

 

Image credit: Alexander Churkin

https://commons.wikimedia.org/wiki/File:Human_eye1.jpg