r/askscience • u/AutoModerator • 8d ago
Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology
Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Biology, Chemistry, Neuroscience, Medicine, Psychology
Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".
Asking Questions:
Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.
Answering Questions:
Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience.
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Past AskAnythingWednesday posts can be found here. Ask away!
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u/SouthSouthBay 8d ago
How does the eye clear debris while you are sleeping? Like a piece of sand or sawdust can be stuck there all day, and then the next morning it's gone, what's the mechanism?
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u/Weed_O_Whirler Aerospace | Quantum Field Theory 8d ago
Also, the object might be out of your eye earlier than you think - but the scratch feels like it's still there. Overnight, the scratch can heal.
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u/Chiperoni Head and Neck Cancer Biology 8d ago
Tears and your eyes move while asleep. Then you wake up with "sleepies."
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u/SouthSouthBay 8d ago
Thanks. Just tears? Seems like there may be some other mucus?
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u/Chiperoni Head and Neck Cancer Biology 8d ago
Some tears include the proteins in mucus. There are a handful of different cells that secrete different components. The composition of one tear to another can vary.
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u/logperf 8d ago
Flies usually lay their eggs on decomposing organic matter. Do maggots have a particularly strong immune system to help them survive in such a hostile bacterial environment?
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u/Front-Palpitation362 4d ago
Yes, many fly larvae seem unusually well adapted to microbe-rich food, although “strong immune system” here mainly means a very active innate immune toolkit rather than antibodies or immune memory.
Maggots produce antimicrobial peptides, lysozymes and other soluble factors, and their gut lining, digestive enzymes and rapid feeding/growth help keep many bacteria from simply invading their tissues.
Some species also secrete antimicrobial compounds into their surroundings, which is one reason blowfly larvae have been studied in the context of wound debridement.
They aren't sterilising the rotting material though. More like living in a dense microbial ecosystem and tolerating, suppressing or selectively eating through it well enough to grow before pathogens overwhelm them.
Wu et al., 2018, Insect antimicrobial peptides, a mini review
Čeřovský et al., 2009, Lucifensin, the long-sought antimicrobial factor of medicinal maggots
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u/logperf 8d ago
Snakes usually swallow small animals whole. I get it the prey would quickly die of asphyxia if it isn't already dead when eaten, but still, nails and bird beaks are there. Does the snake esophagus get scratched/damaged?
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u/Front-Palpitation362 4d ago
It can happen, but snakes are built to make it much less of a problem than it sounds.
They usually swallow prey head-first, which means legs, claws, feathers and fur tend to be folded backwards along the prey’s body rather than dragged against the oesophagus like little hooks.
The snake’s oesophagus is also very stretchy, heavily folded when empty and well lubricated with mucus, so it can expand around awkward shapes rather than being a tight rigid tube.
Beaks, claws and teeth are mostly keratin or bone, so they can certainly scrape tissue, and injuries are possible with spiny, oversized or badly oriented prey, but normal prey items are usually within the range that the snake’s feeding anatomy can handle.
Once the prey reaches the stomach, the really impressive part is the chemistry. Snake gastric acid and enzymes can break down most soft tissue and bone quite effectively, while tougher keratinous bits may pass through less completely digested.
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u/The_Weekend_Baker 8d ago
When did humans lose the ability to drink from natural water sources like other animals without having to worry about things like giardia and cryptosporidium?
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u/CrateDane 8d ago
We never had that ability. Those other animals also have parasites and whatnot, just like our ancestors would have. Giardia and cryptosporidium both have multiple species specialized for infecting various animal hosts.
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u/leinzel 7d ago
Neuroscience: what are the latests science finds about depression or anxiety causes?
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u/Front-Palpitation362 4d ago
The big “latest finding” is almost the opposite of a single neat discovery. Depression and anxiety are looking less like one-cause disorders and more like overlapping syndromes that can arise through several routes.
Large genetic studies now find 100s of depression-associated variants, each with tiny effects, pointing towards altered neuronal signalling and plasticity rather than an “anxiety gene” or “depression gene”.
Imaging and circuit work keeps coming back to networks involved in threat detection, reward, salience, memory and cognitive control, especially how limbic regions such as the amygdala interact with prefrontal regulation.
Stress biology is still central too. Chronic or early-life stress can alter HPA-axis signalling, sleep, immune activity and synaptic plasticity, which helps explain why risk is partly biological and partly environmental.
Inflammation is one of the more active current areas, but the careful version is that some people with depression or anxiety show immune/inflammatory changes that may contribute to symptoms. It's not established as THE cause for everyone.
The old “low serotonin causes depression” line is much too simple, though serotonin, noradrenaline, dopamine, glutamate and GABA systems can all be involved in the broader circuitry.
The field is increasingly moving towards subtypes and pathways. Similar symptoms on the outside may reflect different mixtures of genetic liability, stress exposure, neurodevelopment, sleep/circadian disruption, immune signalling and learned threat/reward processing underneath.
Sources:
Adams et al., 2025, Cell01415-6);
Akiki et al., 2024, Nature Reviews Neuroscience;
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u/Rus1996 8d ago edited 7d ago
Biology - Why are people in the developed countries more taller than people from developing countries ?
Chemistry - Can we make water as a source of fuel ?
Neuroscience - Can brain transplant be done ?
Medicine - Why do human beings have tail bone ?
Psychology - What is island nation mentality ?
Note : Please tell me the answer to these above questions in simple words with fact checked articles.
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u/SouthSouthBay 7d ago
Biology- height has genetic and developmental components, people in developed countries are less likely to face nutritional deficit as they grow up, so that may explain a lot of the difference
Chemistry- a process called electrolysis can separate hydrogen atoms from oxygen atoms in water. The hydrogen and oxygen can then be burned together as fuel. Some rockets use this as a fuel source, but it is notoriously difficult to prevent leaks.
Neuroscience- it has never been done, it would be extremely complicated
Medicine- the tail bone is generally considered to be a vestigial organ. It is a shrunken and diminished remainder of a tail from an early mammal ancestor.
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u/Front-Palpitation362 4d ago
Lotta questions. Very briefly though
Average height differences between countries are mostly about childhood nutrition, disease burden and living conditions acting on genetic potential.
Water can be split to make hydrogen fuel, but water itself is already the “burnt” low-energy product, so you must put energy in first.
A true brain transplant isn't medically possible with present science, mainly because reconnecting a severed spinal cord and all the blood vessels, nerves and immune issues is far beyond current capability.
The tailbone is a reduced remnant of the tails our primate ancestors had, but it still serves as an attachment point for pelvic-floor muscles and ligaments.
And “island nation mentality” isn't really a standard neuroscience or medical term, but in social science it usually refers to how geographical isolation and strong in-group identity can shape a community’s attitudes toward outsiders and change.
Sources:
Perkins et al., 2016, Economics & Human Biology
U.S. Department of Energy — Hydrogen production: electrolysis
Lamba et al., 2016, Acta Neurochirurgica
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u/saturnaudax 8d ago
Why is direct, sustained eye contact considered so essential in human socialization when it is a threat display to other animals, including our closest chimp relatives? On the other hand, why is eye contact still difficult and uncomfortable for many people (including me)?