Sharma, Neelima, Yara Haridy, and Neil Shubin. "Synovial joints were present in the common ancestor of jawed fish but lacking in jawless fish." PLoS biology 23, no. 2 (2025): e3002990.

 

What They Did

The researchers carried out imaging studies on jaw and pelvis joints of embryonic and juvenile skates (which are cartilaginous fish) and skull joints of juvenile and adult lampreys (which are jawless fish). They found that skate joints have cartilage skeleton components shaped so as to fit together, but with a gap between them. These joints appear to function similarly to the joints of humans and other tetrapods, where the bones are lined with cartilage at the joint and separated by a gap filled with lubricating fluid. The lamprey skull joints, however, do not show a similar gap, nor are the components shaped to fit together.

They also found that one type of collagen is found throughout the cartilaginous skeleton, while another kind is only at the edges of joints. Both skates and lampreys produced the same type of lubricating proteins around the joints, and the skate embryos produced signaling proteins around the developing joints. These proteins are also involved in the development and function of tetrapod joints.

In tetrapod embryos, the muscles have to contract for the joints to develop. The researchers added a paralytic to the tank water of some of the skate embryos and found that their joints did not develop normally, suggesting that muscle contraction is necessary for their joint development as well. Finally, they examined the fossil of a placoderm, an extinct fish that developed after jawless fish but before modern cartilaginous fish, and found that it had joints similar to those of skates and tetrapods.

Further Exploration

I learned a bit about bones and joint development while trying to understand this article. All the places where bones are fused together, such as in the skull, are also joints (see https://my.clevelandclinic.org/health/body/25137-joints). The type of joints I usually think of (knees, shoulders, etc.) are called synovial joints, with the synovial membrane providing cushioning between them. Those are the types of joints the researchers looked for in their fish studies.

Most human joints develop from a region of embryonic cells differentiating into two sections of bone-precursor cells, leaving with cells between them that develop into the joint tissues. Those in-between cells pinch apart, leaving a space between them, so you end up with two bones forming a joint from that one region of cells (see https://wisc.pb.unizin.org/mindmotionanatomy/chapter/limb-development/). The jaw joint is different because the jaw bones develop separately from two regions of cells, and then the joint tissues develop from the cells between the bones. I think of the more common joints as developing “from one into two” and the jaw joint as developing “from two into one” – though of course they all consist of two bones forming one joint.

The bones that make up the more common joints also go through a stage of being made of cartilage first, with the bone developing from the cartilage framework. The bones in the skull don’t go through the cartilage stage. I wonder if that difference in development is related to the particular problems associated with TMJ, but that’s a rabbit hole for another day!

Image credit: Andy Martinez / NOAA

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

Sztuka, I. M., Becker, M., & Kühn, S. (2025). Neural representations underlying psychological responses to natural and artificial features in indoor architecture. Journal of Environmental Psychology, 103, 102553.

 What They Did

The researchers recruited adults for a study on psychological responses to indoor scenes. The scenes were categorized by natural or artificial style and by function: commercial, educational, etc.; these prior categorizations were not revealed to the participants. The researchers also evaluated each image for visual features such as hue, saturation, brightness, edge density, etc.

 Each participant completed three tasks: undergoing fMRI while observing a randomized, sequential display of scene images; spatially arranging some of the images on a screen according to their perceived similarity; and rating each image by how much they liked it, how natural it appeared, how much they would want to be in the scene, and how much it evoked feelings of relaxation as opposed to stress. The researchers found that individuals were fairly consistent in their own ratings but that ratings of the same image by different participants were not consistent. They found no correlation between the ratings participants gave the images and the prior categorizations of the scenes.

The researchers spatially arranged all the images based on the combined participant responses. The previously-assigned categories of natural and artificial could be distinguished but did not directly map to a single linear dimension. Rather, the images seemed to be arranged in one dimension by a combination of edge density, saturation, and brightness, with the other dimension not well determined by the measured variables. Finally, the fMRI results showed differences in brain activity, primarily in the visual system, in response to simple visual features but not previously-assigned categories.

 

Further Exploration

Even though the results did not support the hypothesis that people would identify more natural indoor architectural styles and rate them more highly, I found this article really interesting. I wonder if the results have more to do with the images used than with the underlying hypothesis.

The article provides examples of the natural and artificial style images for each category, and those words don’t really describe how I’d distinguish them. In general, I’d say the ones labeled natural have more curves and somewhat more color. The artificial ones are all stark whites and right angles. In most cases, I prefer the ones labeled natural, but I wouldn’t say they look more natural as much as that the ones labeled artificial look cold and boring.

Part of the reason none of them feel natural for me is that there are no plants. This was intentional on the part of the researchers; they wanted to focus on other characteristics that generate a sense of naturalness, not on literal exposure to vegetation. Similarly, there are no rocks: no boulders or pebbles or sand. For me, being in nature really means being in contact with nonhuman life and with the raw elements. There are other traits that affect whether indoor spaces are comfortable (including being able to see plants and rocks) but they will never be natural per se. Whether natural is correlated with comfortable for me probably depends on a whole lot of factors, but that’s a rabbit hole for another day!

Image credit: Public domain, contributor listed as "Vincent"

https://commons.wikimedia.org/wiki/File:Wageningen_University_-_Building_Lumen.JPG

Ulaszewski, Bartosz, Marcelo Sandoval-Denis, Johannes Z. Groenewald, Marileide M. Costa, Bagdevi Mishra, Sebastian Ploch, Pedro W. Crous, and Marco Thines. "Genomic features and evolution of lifestyles support the recognition of distinct genera among fusarioid fungi." Mycological Progress 24, no. 1 (2025): 20.

 

What They Did

The researchers carried out a genetic comparison of fungus species in or closely related to the genus Fusarium in the family Nectriaceae. In addition to the 236 genomes already available, they sequenced another 40 from a variety of genera for a more representative sample of the family. A fungus in a related family was used as the outgroup, expected to be similar to the ancestral state of Nectriaceae.

By comparing 263 genes that were present in all the genomes, they determined which genomes were most similar and therefore more likely to represent closely related species. They found that the species within the Fusarium genus were in fact more genetically similar to each other than to members of other genera and that accepted taxonomic groups within the genus also largely matched the genetic relationships.

The fungi in the family Nectriaceae have a variety of survival strategies: many primarily live on or in plants; a handful are insect symbiotes; several are saprotrophs that digest decaying organic matter; and a few live primarily on other fungi or on animals. The researchers concluded that the common ancestor of all Fusarium species was likely a plant pathogen. Although some members of the genus do grow inside plants without causing disease, they may become harmful if the environment changes. The common ancestor of Fusarium and closely related genera was probably either a plant pathogen or a saprotroph, but since the earliest diverging groups are saprotrophs, the researchers believe that to be the more likely ancestral niche.

 

Further Exploration

The authors mentioned that the species Fusarium xyrophilum produces pseudoflowers on plants in the genus Xyris. It grows within the plant and causes sterility, then forms fruiting bodies that look like the flower petals (see https://www.ars.usda.gov/news-events/news/research-news/2020/fungus-commits-floral-fraud-to-fool-insects-into-spreading-it/.) Not only does it look like a flower to human eyes, but it also reflects ultraviolet light for insects and produces an attractant chemical. The insects that are normally pollinators of Xyris land on the fungus and carry spores to new hosts.

There’s also a Fusarium that’s an animal pathogen, aptly named F. veterinarium. I couldn’t find much information about it; apparently it was only described in 2018 (see https://wi.knaw.nl/details/89/567135.)  Several other Fusarium species, however, can cause animal diseases (see https://www.midogtest.com/blog/impacts-of-the-pathogenic-fungus-fusarium-in-animals/.) Of the animal pathogens on the linked site, F. oxysporum is closely related to F. veterinarium, so it’s not surprising that it can affect animals, even though it’s primarily a plant pathogen. Fusarium verticillioides, F. graminearium, and F. solani are also primarily plant pathogens, though F. solani is now in the genus Neocosmospora. Fusarium culmorum is primarily a saprotroph.

Fungi used to have different names for the sexual and asexual forms, which made sense because they can look different and even produce different types of spores. It’s not quite like the alternation of generations in plants, with a regular switch between sexual and asexual forms. Instead, the type of reproduction is determined by environmental conditions. There are a lot of details about how sexual reproduction works in fungi, but that’s a rabbit hole for another day!

Image credit: Tashkoskip

https://commons.wikimedia.org/wiki/File:Culture_soil_fungus_Fusarium_sp._with_purple_color.jpg

Stump, A., Wüstenberg, T., Rouder, J. N., & Voss, A. (2025). The face of illusory truth: Repetition of information elicits affective facial reactions predicting judgments of truth. Cognitive, Affective, & Behavioral Neuroscience, 1-14.

What They Did

The researchers recruited 75 German university students for a study of the “illusory truth effect,” in which repetition of information affects perception of its accuracy. Each participant wore electrodes recording activation of facial muscles involved in furrowing the eyebrows, raising the eyebrows, and raising the corners of the mouth. They read statements on a screen, half of which were true and half false.

For the first part of the study, they sorted statements into assigned categories. Ten minutes later, they rated presented statements as true or false. Half of the statements were among those that were sorted, and half were new. One week later, participants performed the statement-rating task with a combination of new statements and statements from the sorting task that had not been used in the previous statement-rating task.

The researchers found that participants responded more quickly to statements they had previously seen, with a much larger difference between “new” and “old” reaction times after the ten-minute interval than the one-week interval. Participants were also more likely to rate “old” statements as true: about 2.5 times more likely after ten minutes and about 1.4 times more likely after one week. The researchers found greater activation of the eyebrow furrowing and raising muscles when participants were presented with new statements after ten minutes but not one week. Eyebrow furrowing muscle activation was also lower when participants rated statements as true after either interval. The researchers note that their results provide a physiological indicator correlated with the illusory truth effect.

Further Exploration

I’m curious about whether the strength of the illusory truth effect varies between neurotypical and neurodivergent populations. One study suggested that autistic people are less likely to be influenced by irrelevant information in making product choices (see https://www.bps.org.uk/research-digest/why-autistic-people-may-be-less-susceptible-marketing-tricks but also https://kirstykendall.com/autistic-people-commercials/). I suspect that I’m neurodivergent, and I was surprised that the illusory truth effect still held in the experimental conditions: the statements were chosen not to be emotionally evocative and participants were told that some statements would be true and some false.

I can see how repetition would lead to belief that a statement is true if it was repeated from multiple sources and personally relevant – things like being told repeatedly from childhood that vegetables are healthful. But if random statements like those in the study started appearing on billboards, I think I would 1) think this was really cool, 2) start fact-checking the statements after I’d seen them a few times, and 3) get angry that false statements were being presented as true.

 The paper explains that processing familiar statements takes less cognitive effort, which makes people more relaxed, which is conflated with a sense of truth. But this also only happens when familiar and unfamiliar information are mixed. I feel like having unfamiliar information mixed with familiar information that I thought was true would make me more likely to trust the unfamiliar information. Of course, it could also be that I don’t have as much self-knowledge as I think I do, but that’s a rabbit hole for another day!

Image credit: Kurt Kaiser

https://commons.wikimedia.org/wiki/File:True_or_false_graphic.png

Ibáñez, Alejandro, Bartłomiej Zając, Izabella Sambak, Michał Woźniakiewicz, Aneta Woźniakiewicz, and Maciej Pabijan. "Chemical signal diversity in male sand lizards (Lacerta agilis) along an urbanization gradient." Scientific Reports 15, no. 1 (2025): 6958.

 

What They Did

The researchers captured male sand lizards (Lacerta agilis) from urban, suburban, and rural areas around Krakow, Poland and compared the chemical composition of their femoral gland secretions, which are involved in attracting mates. They found that urban and suburban lizards tended to produce a more varied mix of compounds than rural lizards. In addition, the compounds dodecanoic acid, tetradecanoic acid, n-pentadecanoic acid, (+)-α-tocopherol, and cholecalciferol were the most important in distinguishing lizards from different areas. Dodecanoic acid, tetradecanoic acid, and n-pentadecanoic acid are all fatty acids, (+)-α-tocopherol is a form of vitamin E, and cholecalciferol is a form of vitamin D. 

The secretions from suburban lizards had the highest amounts of dodecanoic acid, tetradecanoic acid, n-pentadecanoic acid, and cholecalciferol. Secretions from suburban and urban lizards had the most (+)-α-tocopherol. Secretions from urban lizards had more tetradecanoic acid and cholecalciferol than those from rural lizards, but less than those from suburban lizards. 

The researchers suggest that the greater variety of compounds produced by lizards in more human-influenced habitats may be related to the complexity of those environments compared to the rural habitat, which consisted of fairly uniform forest and meadow. They note that fatty acids are also energy sources for the lizards, so secreting them has a cost, which implies some benefit that outweighs that cost in suburban environments. The  (+)-α-tocopherol and cholecalciferol may function as mate-attractants themselves, and the (+)-α-tocopherol may also help preserve the mate-attractant compounds from ultraviolet radiation, which is more abundant in areas without a tree canopy.

Further Exploration

Anoles are one of the most common lizards in my area, and it turns out they differ from most other lizards in that they don’t produce the femoral gland secretions, which might be related to their more visual displays of flashing their dewlaps and doing “push-ups” (see https://www.anoleannals.org/2020/06/05/vasotocin-and-chemical-communication-in-anolis-carolinensis.) 

I was also surprised to see that the sand lizard researchers used the Shannon index to compare the diversity of femoral secretion chemicals among lizards. I’m used to seeing the Shannon index used to compare species diversity among different habitats, vegetation survey plots, and the like. But of course, it’s just math, and you can have the categories be anything you like. [If you’re not familiar, the Shannon index is equal to  -Σp_i * ln(p_i), where p_i is the proportion of each species relative to the total. You add up the proportion times the natural log of the proportion for each species, then change the sign because the natural log of a number less than 1 is negative]. This makes me think it would be fun to calculate the Shannon index of my local library by book categories such as fiction type (fantasy, romance, etc.) or Dewey Decimal range. 

The researchers also used nonmetric multidimensional scaling to visualize the degree of secretion chemical similarity among the lizards; I’m again much more familiar with this method for showing the similarity among survey plots, generally for plant species composition.  I’m curious what other applications it might have, but that’s a rabbit hole for another day!

Image credit: Reinhold Möller 

https://commons.wikimedia.org/wiki/File:Fighting_Sand_lizards_(Lacerta_agilis)_4295304.jpg

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I interrupt your regularly scheduled blog post with a reminder that I am looking for full-remote work in research, editing, or scientific/academic communication. This blog is partially intended to showcase my skills in communication and comprehension across several disciplines. If you think you or your organization might have a use for my abilities or if you'd like a copy of my resume, please leave a comment or email me: kimberly.a.israel [at] gmail.com. Check back next weekend for new content! [It's going to be that kind of week ;-) ]

Das, P. K. Some salient Linguistic features of Complex Predicates in Hindi. Strength for Today and Bright Hope for Tomorrow Volume 25: 2 February 2025 ISSN 1930-2940, 1.

 What They Did

The researcher explored the use of “light verbs” in Hindi to create new grammatical constructs. For example, the verb “rəhnɑ” meaning “to stay” can work as a light verb that indicates the progressive tense, such as the difference between “writes” and “writing.” It can even combine with itself to mean “staying.”

When “rəhnɑ” is used that way, it loses the meaning it has on its own: to be writing doesn’t mean to write in one place. Similarly, the verb “gəyɑ” meaning “went” loses the meaning of having gone somewhere when it’s used as a light verb to express past tense. Adding it can change the meaning of a verb from “sit” to “sat” but it doesn’t mean the person physically moved somewhere else to sit, just that the sitting action occurred in the past.

In Hindi, some of these light verbs can also combine with nouns to create phrases that work like verbs. For example, “remember” is more directly translated as “do remembrance.” The word “ɑwɑz” meaning “call” is only a noun; to call someone would be to “give call.” Light verbs can also change the connotation of the main verb. The word “lenɑ” means “to take” while “genɑ” means “to give.” For the sentence “He read my letter,” using “lenɑ” to mark past tense implies that the person shouldn’t have read the letter, while using “genɑ” implies that the person read the letter as a favor to the addressee. Therefore, these light verbs keep part of their original meaning.

 

Further Exploration

I know I didn’t do this article justice; that would require more time and words than are feasible for my free-time blog. I’m fascinated by linguistics but have never formally studied it. My knowledge comes mostly from the books and videos of John McWhorter plus a smattering of others and whatever internet articles I happen to stumble upon.

It was surprising to me that Hindi doesn’t have verbs for “to remember”, “to call”, and several others, but of course other languages have verbs that English doesn’t, like the different words for “to know (a fact)” and “to know (through familiarity)” that occur in French and Spanish. It’s also fun that in English, “call” is both a noun and a verb, so “call me” works, but so does “give me a call.” The way Hindi light verbs affect connotation sounded new to me, so I looked for more information on their role in English (see https://blog.oup.com/2022/02/what-are-light-verbs). There are so many more than I realized; once you start looking, they’re everywhere! My favorite example of light verbs affecting connotation in English is the difference between “having coffee” and “drinking coffee.” It’s also funny how we say “doing homework” and don’t have “homeworking” as its own verb.

I noticed that the journal today’s article appears in is called Strength for Today and Bright Hope for Tomorrow, which is also a phrase from the Christian hymn “Great is Thy Faithfulness.” I wonder what the story is there, but that’s a rabbit hole for another day!

Image credit: Alberthenry1988

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

Manet, M. W. E., Kliphuis, S., Bas Rodenburg, T., Goerlich, V. C., Tuyttens, F. A. M., & Nordquist, R. E. (2025). Shining light on the laying hen brain: the effect of light during incubation depends on cognitive task and hybrid. Animal Behavior and Cognition, 12(1), 45-68. https://doi.org/10.26451/abc.09.01.03.2022

 What They Did

The researchers incubated chicken eggs with half of them kept in 12-hour periods of darkness and green light and the others kept in total darkness. After hatching, the brains of the male chicks were dissected to compare the effects of the incubation condition on the distribution of particular proteins in the brain. In natural conditions, unequal light exposure between the two eyes is believed to affect the protein distribution, leading to greater specialization of the brain hemispheres. The brain dissections, however, did not reveal significant differences between the chicks from eggs in the two incubation conditions.

The female chickens were used in additional experiments as adults. In the first experiment, chickens had to move to the left or right to pass a barrier in the center of a pen. The chickens from eggs incubated with light were more likely to pass the barrier consistently on the same side, suggesting greater brain hemisphere differentiation.

In the second experiment, chickens were individually offered a grid of nine cups containing mealworms. Chickens that finished the test more quickly with less time spent revisiting empty cups were believed to have better working memory. Finally, chickens were individually placed in Y-shaped pens, with each branch of the Y housing a familiar or unfamiliar chicken. Test chickens that spent more time with either the familiar or the unfamiliar chicken were believed to be able to tell the two chickens apart. Neither of the final two tests showed significant differences between chickens from light-incubated and dark-incubated eggs.

Further Exploration

Even though this study had few statistically significant results, I still found it interesting. I wouldn’t have even predicted that egg incubation with light or darkness would affect the chickens, but other studies have shown effects of early experience on brain development. In one of my undergraduate psychology classes, I learned that kittens raised the first few weeks in an environment with only vertical lines would grow up unable to see horizontal lines and vice versa (see https://www.psychologytoday.com/intl/blog/brain-food/201404/the-cat-nobel-prize-part-ii.)

Of course, a chicken in the egg is more like a mammal in the uterus, but there’s some evidence that human fetuses, particularly in the third trimester, have some sensitivity to light and dark, sounds both inside and outside the mother’s body, and flavor chemicals from the mother’s food (see https://www.webmd.com/baby/features/in-the-womb). For the chickens, there’s concern over their welfare because incubation in total darkness doesn’t reflect the natural condition; the mother hen occasionally gets up off the nest. But a human fetus is unlikely to experience sensory deprivation in the womb, so parents don’t need to worry about that.

The results of the chicken experiments above didn’t meet the researchers expectations, and they suggest that the “working memory” test may have been too easy to distinguish between different levels of cognitive ability. The whole structure of the test seems to assume that chickens understand that mealworms won’t spontaneously reappear once they’re removed from a cup, and I don’t know whether that understanding has ever been tested, but that’s a rabbit hole for another day! 

Image credit: Vyperx1

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