The hottest Physiology Substack posts right now

And their main takeaways
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Top Science Topics

Puzzling out elephant longevity

Trevor Klee’s Newsletter • 2014 implied HN points • 07 Dec 25
🔬 Science Physiology
  1. Elephants' low cancer rates and long lives are tied to many non-identical TP53 copies—retrogenes and a reanimated pseudogene—that work together with their immune and DNA-regulatory systems.
  2. Other long-lived animals like bats use different strategies, emphasizing DNA repair and immune modulation along with regulated p53 activity rather than just more cell-suicide signals.
  3. Longevity is multi-factorial and species-specific, so a single explanation (like extra TP53 copies) is incomplete and can't be copied into another species without integrating many other systems.

How Our Gut Microbiome Can Drive Sugar Cravings

Ground Truths • 15222 implied HN points • 26 Jan 25
🏥 Health & Wellness Physiology
  1. Our gut bacteria can influence our cravings for sugar. Specific bacteria in our gut send signals to our brain that can make us want more sweets.
  2. The molecule Ffar4 in our gut plays a big role in how much we like sugar. When this is less active, we might crave sugar more.
  3. A certain type of gut bacteria, called Bacteroides vulgatus, is linked to an increased desire for sugar. Understanding this can help us figure out how to control cravings better.

What Makes Men and Women Different?

Uncharted Territories • 2162 implied HN points • 04 Sep 23
🔬 Science Physiology
  1. Women and men think differently due to biological differences like having a uterus, leading to significant psychological variations.
  2. Men and women face different stakes in relationships and reproduction, with women having higher commitments and limitations due to their reproductive capacity.
  3. Evolutionary factors have shaped men to compete for access to females, leading to traits like dominance, aggression, physical strength, and risk-taking behavior.

Learning about longevity from long-lived animals

The Works in Progress Newsletter • 30 implied HN points • 10 Feb 26
🔬 Science Physiology
  1. Long-lived animals use different tricks — extreme regeneration, strong DNA repair and cancer defenses, and very slow metabolisms — any of which could teach us about aging.
  2. Humans already have some longevity advantages like big brains, long childhoods, social roles, and certain cancer-fighting adaptations, but these traits come with evolutionary tradeoffs.
  3. We can extend life by treating specific diseases or by targeting fundamental aging (telomeres, DNA repair, metabolism); promising approaches include telomerase work, mTOR inhibitors, diabetes drugs, and caloric restriction, but they carry risks like cancer and other tradeoffs.

Some ants can choose to live 5x as long

Trevor Klee’s Newsletter • 746 implied HN points • 11 Feb 25
🔬 Science Physiology
  1. Some ants, like Indian jumping ants, can live much longer lives if they become a pseudoqueen. They can live about five times longer than their worker counterparts after winning a duel for queen status.
  2. The lifespan of these ants can actually change based on their circumstances. If a gamergate is placed in a new colony with an active queen, they revert back to being a normal worker with a shorter lifespan.
  3. This interesting case suggests a different relationship between reproduction and lifespan. In these ants, becoming a reproductive figure seems to extend their life instead of shortening it like it does in many other species.
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If langurs can drink seawater, can humans do so as well?

Trevor Klee’s Newsletter • 895 implied HN points • 14 Nov 24
🔬 Science Physiology
  1. Cat Ba langurs can drink seawater and survive in dry conditions due to their diet and unique adaptations. They mainly get water from the leaves they eat, which helps them thrive on an isolated island.
  2. Humans cannot drink seawater without serious health issues. Consuming saltwater leads to dehydration because our bodies can't remove the excess salt fast enough.
  3. Research suggests that Cat Ba langurs have special genetic traits that allow them to manage salt and calcium better than most mammals. This helps them live in their harsh environment.

What’s The Real Story With Altitude Training?

Beck of the Pack • 117 implied HN points • 12 Jan 24
🎾 Sports Physiology
  1. Altitude training can improve performance by increasing red blood cell production.
  2. Training at high altitude may not be enough on its own; 'live high/train low' might be the key to performance gains.
  3. Shorter recovery time, iron supplements, and acclimatization time are important considerations for high-altitude training.

Questions on Protein and Longevity, SHBG, and Trouble Hydrating

Harnessing the Power of Nutrients • 519 implied HN points • 23 Aug 22
🏥 Health & Wellness Physiology
  1. Cycling between fasting and feeding states may provide benefits similar to protein or calorie restriction for longevity.
  2. Several factors like vitamin K2, insulin sensitivity, thyroid hormone, and fasting physiology influence levels of SHBG.
  3. When salted water doesn't hydrate as effectively as an IV, it might be due to poor salt absorption, which could be helped by consuming glucose, starch, or a meal alongside.

Simulate Your Next Marathon Race Pace

The Healthtech Initiative • 2 implied HN points • 20 Feb 26
🎾 Sports Physiology
  1. A predictive marathon model built from 101 runners explains about 79.3% of the variation in finish times and has an average prediction error of roughly 18.3 minutes.
  2. Running performance is framed as two parts: baseline ability (like genetic or starting pace) and adaptation to training (how much fitness you gain per minute of training).
  3. About 21% of finish-time differences are unexplained — things like weather, illness, sleep, motivation, nutrition, and luck — which shows there are real limits to modeling human performance.

The Nose Knows

Weekly Wisdom • 159 implied HN points • 08 Dec 22
🏥 Health & Wellness Physiology
  1. Breathwork is essential since the breath is a constant companion, affecting both body and mind.
  2. Various breathing techniques can be used for specific effects like calming the nervous system, increasing alertness, or improving oxygen absorption.
  3. Understanding the different elements of breathing, such as nostrils, lungs, and techniques like Breath of Fire, can lead to improved well-being and mind-body connection.

Meditation as Wakeful Relaxation: Unclenching Smooth Muscle (26/30)

psychotechnology • 12 implied HN points • 27 Nov 25
🏥 Health & Wellness Physiology
  1. Relaxation and wakefulness can coexist: training “wakeful relaxation” means coordinating mind and body to release tension, which makes you less reactive and reduces anxious mental looping.
  2. Patterns of muscle tension—especially in vascular smooth muscle—act as bodily “stances” that stabilize certain feelings and thoughts, and persistent smooth‑muscle latches can shape experience with relatively low energy cost.
  3. You can work to unclench these latches through targeted practices like ultra‑slow body scans, deliberate clench‑release cycles, and heat/cold exposure, using attention to track and loosen latched tissues.

Short Thoughts on Bile

Autoscriptorium • 39 implied HN points • 27 Apr 23
đź“š Literature Physiology
  1. Bile is described as irritability and prickliness, associated with making choices and rejecting alternatives.
  2. In American business culture, showing bile or criticism is often viewed negatively, seen as a flaw in character.
  3. The theory of temperament based on humours, like black bile and yellow bile, influences personality traits and physical symptoms.

My Brain, My Cartographer

Affective Medicine • 39 implied HN points • 19 Sep 23
🏥 Health & Wellness Physiology
  1. Affect is a composite of many factors including valence and arousal
  2. The brain maps the body to process interoception and simulate different body states
  3. Feelings are mental representations of different body states, indicating the brain generates and simulates feelings

in person nation vs impersonation

bad cattitude • 147 implied HN points • 08 Feb 24
🔬 Science Physiology
  1. Genes affect all kinds of traits and behaviors in animals, including humans.
  2. Physical appearance and body language play a significant role in human interactions and societal outcomes.
  3. Changes in technology and society can impact evolution and genetic traits over time.

Yes, You Have a Homeostat

The Heart Attack Diet • 19 implied HN points • 02 Sep 23
🏥 Health & Wellness Physiology
  1. Animals need to maintain the right amount of stored fat for survival; too little makes them vulnerable, too much impairs movement and fighting abilities
  2. Having a homeostat helps animals regulate their fat levels and stay at their optimal weight consistently without much effort
  3. Different animals have different ideal fat percentages based on their needs and roles, and the homeostat system ensures they stay within these ranges

Goal creates the functioning

The Nature of Training • 1 HN point • 06 Jul 24
🏥 Health & Wellness Physiology
  1. Biomimetics uses natural organisms as inspiration to create innovative technology, like airplanes inspired by bird wings and Velcro by burdock seeds.
  2. The traditional view of organisms as machines with replaceable parts is being challenged, with organisms seen as complex systems that self-organize to maintain equilibrium and adapt to their environments.
  3. Understanding an organism's purpose and stimuli is more important than focusing on its individual parts, allowing for better responses to training and health needs.

It's Not You. It's Your Biochemistry

Neuro Athletics • 17 implied HN points • 11 Mar 24
🏥 Health & Wellness Physiology
  1. Your physiology and biochemistry, not your circumstances, play a key role in determining your potential and performance.
  2. Optimizing recovery is crucial for reaching peak performance, reducing risks of burnout and enhancing physiological resilience.
  3. Personalized approaches that consider unique biochemical and physiological profiles are vital in unlocking individual potential for peak performance.

020: Insulin Resistance Isn’t All About Carbs and Insulin

Harnessing the Power of Nutrients • 59 implied HN points • 24 Aug 16
🏥 Health & Wellness Physiology
  1. Insulin resistance is not solely related to carbs and insulin, but also influenced by responses to obesity, exercise, and diet choices.
  2. Reactive oxygen species (ROS) play a central role in the physiology of insulin resistance.
  3. Practical strategies to prevent and reverse insulin resistance include focusing on nutrient density, body composition, and considering long-term effects of low-carbohydrate diets.

Repeat After Me: The Liver Is Not a Filter!

Harnessing the Power of Nutrients • 19 implied HN points • 17 Mar 19
🏥 Health & Wellness Physiology
  1. The liver does not filter toxins, but helps in eliminating them through bile, feces, and urine
  2. Hepatic detoxification occurs in three phases, modifying toxins to make them less toxic and water-soluble
  3. It's important to correct the misunderstanding that the liver is a filter by educating others at different levels of scientific understanding

036: Is Insulin Really a Response to Blood Glucose?

Harnessing the Power of Nutrients • 19 implied HN points • 30 Jul 17
🏥 Health & Wellness Physiology
  1. Insulin serves more functions beyond regulating blood glucose, such as affecting energy use and metabolic pathways.
  2. Insulin release is tied to total energy supply and energetic versatility, not solely blood glucose levels.
  3. Understanding the complex processes of insulin signaling sheds light on how different nutrients impact the body's energy metabolism.

035: The Biochemistry of Why Insulin Doesn’t Make You Fat

Harnessing the Power of Nutrients • 19 implied HN points • 22 Jul 17
🏥 Health & Wellness Physiology
  1. Insulin doesn't directly make you fat; it's regulated by energy needs and availability at a biochemical level.
  2. All biochemical pathways, including the storage of fat by insulin, are influenced by cellular energy levels.
  3. Although insulin promotes fat storage, it also boosts glucose oxidation, leading to no net change in caloric balance.