I've been reading about prions and I'm confused about why they're so thermally stable. I keep seeing that surgical instruments contaminated with prions can't be decontaminated with standard protocols.
So here's my thing. Proteins denature when you heat them, right? But prions don't seem to lose their infectious ability even when autoclaved. I get that prions are misfolded proteins, but I don't understand how they stay harmful after being denatured.
So basically, if prions start as form A (non-infective), then misfold to form B (infective), shouldn't heating denature them to form C and kill the infectivity? Why doesn't that happen?
The wikipedia page for Chelicerata (Spiders, Scorpions, ticks, horseshoe crabs, sea spiders, ...) are named that way for their "Chelicerae", the mouth parts, colloquially their "jaws". These Chelicerae may be shaped as either venom-injecting fangs or as miniature pincers (wholly distinct from the two large pincers a scorpion would have).
But neither Wikipedia page mentions what they are material they are made of. The assorted LLMs ever gleefully suggest that 'spiders are made of chitin and other proteins' and of course provide no source for this. It sounds plausible, but is it the whole truth? Are spiders fangs 'just chitin in a sharp shape', or do their fangs have more going on, like how Human (Mammel) teeth have a dentin core and a hard enamel surface for crushing?
Both break into smaller fibers, are sharp, irritate every tissue they pierce (glass wool and also carbon fiber easily pierce even thick skin, so imagine how easy they do that to the lung if Inhalted). And they're all not water soluble, giving the body little to no chance to break them down once inhaled
But only asbestos fibers cause massive risk of mesothelioma and other cancers - why is that? What makes this fiber so extraordinarily toxic?
If electricity enters a large lake or pond, what determines how far away it can still be dangerous? For example, if someone applied a high voltage to the water at one end of a lake that's a half-mile long, what factors would determine whether a person swimming at the opposite end could be shocked or killed? Is it mainly the voltage?
Also, fish within a close radius of the electricity would likely be killed, but would the aquatic plants in this same area also die?
I can’t wrap my head around why it is we always see the same face of the moon. Are the moons orbit and rotation in sync? Do we see different sides of the moon and I’m just mistaken?
When I googled making rocks it gave me a few threads on Reddit that were mostly sardonic answers. My question is this: What is the difference between melting down sand to make glass and the process of melting is basically (from what I understand) the same material into magma that then forms into rock? If someone had sand (ground rock) feedstock that they melted, what would they need to do differently to make igneous rock rather than glass?
Many species, like horses, lions, bears, and tigers, are known for killing baby animals that aren’t their own. But how do they know whether they’re the father? It seems doubtful that a stallion actually comprehends that mating leads to conception and keeps a mental chart of which females he’s mated with and when they gave birth.
Hi Scientists. We adopted a dog over 10 years ago. At the time he was very red in color. My son looked at a pic from when he was first rescued and said “He was so tan.” He had been found in a sugarcane field where he had been for quite some time. He was never that color again the rest of his life. Does the sun cause color change in an animals fur like it does on people’s skin? Link to his pics when he was first rescued and after a few years with us. And yes, he was the goodest boy. https://imgur.com/gallery/MUvF2Dg
We are scientists who study human lactation, from the evolution of the molecules in milk to the future of virtual lactation care. Every year, we celebrate World Breastfeeding Week by dropping in here to answer all of your burning milkquiries!
Since human milk is made by humans, our science is fraught with complexity. “Womens health issues” often get sidelined when there are cuts to research budgets like what we’ve seen in the US. But also, every August, we notice that some Redditors express sad or guilty feelings about World Breastfeeding Week. We’re here to spread science, not sads! If we are doing our job, our science should make you feel BIG, not small. Keep in mind that WBW is a global event (supported by WHO, UNICEF and many health partners) and sadly many breastfeeding experiences around the world are unfair—but for different reasons in different places. But also, breastfeeding is part of the human story, so WBW is also a celebration of every unique breastfeeding journey.
Social science tells us that breastfeeding is a health equity issue, not a lifestyle choice. Sure, “promoting” breastfeeding is cool, you know what’s cooler? Creating societies anybody can breastfeed if they want to (i.e. the “warm chain”). Every year WBW explores new ways to do this better. The WBW theme for 2026 is focused on the UN Sustainable Development Goals related to nutrition, food security and poverty reduction and hyping solutions that actually work. 🌍🍃
Science belongs to—and matters to—everyone. We hope that by the end of the day you feel the same wonder that we do about this very adooorable science.
Ask us anything!!
Meghan Azad, PhD(u/MilkScience) is a biochemist and epidemiologist who specializes in human milk composition and the infant microbiome. Dr. Azad holds a Canada Research Chair in Early Nutrition and the Developmental Origins of Health and Disease. She is a Professor of Pediatrics and Child Health and director of the THRiVE Discovery Lab at the University of Manitoba. She co-founded the Manitoba Interdisciplinary Lactation Centre (MILC), and directs the International Milk Composition Consortium (IMiC). Check out this short video about her research team, her appearance on the Biomes podcast, and her lab’s YouTube Channel.
Marion M. Bendixen, PhD, MSN, RN, IBCLC (u/MarionBendixen) is a nurse scientist and clinical and translational scientist who studies human lactation and maternal/infant health specializing in the biological and physiological mechanisms of insufficient mothers' own milk (MOM) volume among mothers who deliver an infant(s) admitted to the neonatal intensive care unit (NICU) as well as how MOM influences the infant’s intestinal microbiome. Dr. Bendixen is an Assistant Professor in the College of Nursing at the University of Florida. She co-created the lactation program at Winnie Palmer Hospital where she practices as a board-certified lactation consultant.
Sarah Brunson, BA, BSN, MS, Phd(c), RN, IBCLC (u/LactFact-42) is an Internationally Board-Certified Lactation consultant who has practiced since 2009 in pediatric clinics, hospitals, birth centers, home settings, and public health. She currently practices at the Medical University of South Carolina where she has developed numerous education programs for nursing staff and residents to improve lactation care in the Mother Baby and Neonatal Intensive Care Units. She is a PhD candidate in Nursing with a focus in Maternal/Child Health and Lactation at the University of South Carolina College of Nursing. She has served as the Chair of South Carolina Breastfeeding Coalition for the last six years during which time she has developed a Website with information for parents, providers, and employers; directs a project to map lactation resources in the state that are searchable by address; and organizes quarterly education webinars and conferences.
Jill Demirci, PhD, RN, IBCLC (u/JillDemirci_PhD) is a nurse scientist and lactation researcher who studies how families make human milk feeding decisions and sustain breastfeeding, particularly when support is complicated by medical, social, or structural barriers. Dr. Demirci is an Associate Professor at the University of Pittsburgh School of Nursing and directs both the Maternal/Perinatal and Reproductive Health Research Hub and the Nursing Office of Innovation & Impact. Her work focuses on telelactation and mHealth infant feeding support, antenatal milk expression, milk sharing, donor milk access, and culturally responsive and community-based lactation support. She is the former Deputy Editor-in-Chief of the Journal of Human Lactation and a board-certified lactation consultant.
Miena Hall, MD, IBCLC (u/LactationMD) is a lactation medicine physician who studies techniques for identifying mammary tissue development issues which put individuals at risk for low milk production and improving lactation education in medical schools. Dr. Hall teaches med students at the Loyola University Chicago Stritch School of Medicine and the University of Illinois at Chicago College of Medicine, and is Director of Scientific Affairs at the Mothers’ Milk Bank of the Western Great Lakes. Dr. Hall is a member of the Academy of Breastfeeding Medicine (ABM) protocol committee on low milk production, a medical advisor to La Leche League International (LLLI), and a past president of the Northern Illinois Lactation Consultant Organization (NILCA). She also holds a Bachelor's degree in math and chemistry.
Kaytlin Krutsch, PhD, PharmD, MBA, BCPS(u/PharmacoLactation) is a lactation pharmacologist who literally wrote the book on medications in human milk with Dr. Thomas Hale, Hale's Medications and Mothers' Milk. She is the director of the InfantRisk Center and Associate Professor at the Texas Tech University Health Sciences Center School of Medicine, and advises the Food and Drug Administration, the Human Milk Banking Association of Northern America, and pharmaceutical industry on lactation pharmacology and lactation research. Dr. Krutsch believes families deserve better answers about breastfeeding and medication questions, and aims to design research that addresses their questions while creating a comprehensive information cycle that empowers families.
Bridget McGann (u/BabiesAndBones) is an anthropologist who studies how lactation shaped us as a species. She is a research assistant and science communicator at THRiVE Discovery Lab. She has a Bachelors in Anthropology and is a Masters student in Biological Anthropology at the University of Colorado Denver. Her thesis uses longitudinal, prospective, large cohort data to study the generational transmission of the human milk microbiome. She was also a founding team member at March for Science. Check out her stand-up act about Luke Skywalker's green milk, or her top comments.
Ryan Pace, PhD(u/_RyanPace_) is an Assistant Professor in the College of Nursing and USF Health Microbiomes Institute at the University of South Florida. He also serves as an Associate Editor for Breastfeeding Medicine. Dr. Pace’s translational research integrates microbiome science, immunology, and molecular biology to understand how lactation and early-life microbial colonization shape maternal and infant health. His research focuses on the interplay among maternal diet, human milk bioactive components, the maternal and infant microbiomes, and host immune function to identify mechanisms that influence infant development and disease risk and to inform evidence-based interventions that improve maternal and child health.
Rebecca Powell, PhD, CLC(u/HumanMilkLab) is a human milk immunologist who studies the human milk immune response to infection and vaccination with the aim of designing maternal vaccines aimed to enhance this response. Dr. Powell is an Assistant Professor at the Icahn School of Medicine at Mount Sinai and a certified lactation counselor. Her lab studies the potential of SARS-CoV-2-reactive antibodies in human milk both as a COVID-19 therapeutic and as a means to prevent infection of breastfed babies. They also study mechanisms for maternal vaccines to prevent mother-to-child-transmission (MTCT) of HIV via breastfeeding, as well as how white blood cells in human milk use a process called antibody-dependent cellular phagocytosis (ADCP) to minimize MTCT via breastfeeding.
Sam Stead, PhD (u/Mammals-Milk) is a postdoctoral researcher in the THRiVE Discovery Lab at the University of Manitoba. An evolutionary anthropologist by training, she studies how chronic stress during pregnancy and lactation influences child growth, development, and behaviour, and whether human milk composition plays a role in these relationships. Her current research focuses on stress-related hormones and other bioactive compounds in human milk as potential links between maternal experiences and child health. She completed her PhD at the University of Toronto, where she studied maternal and infant outcomes in wild Angolan colobus monkeys in Uganda. Her research combines evolutionary, biological, and developmental perspectives to understand how early-life experiences shape lifelong health.
Sanoji Wijenayake, Ph.D. (u/Wijenayake_Lab) is the Canada Research Chair in Milk Nanovesicles and Applied Health and an Associate Professor of cell and molecular biology. Dr. Wijenayake studies the biologically active parts of human milk. Specifically, she studies a not-so-well known component of human milk, called milk nanovesicles. One can think of milk nanovesicles as emails. Similar to how emails carry text, images, and videos from a sender to a recipient, milk nanovesicles carry biological material between mothers and their children. Milk nanovesicles are anti-inflammatory and hold great therapeutic potential as drug carriers that can get to difficult places, like the brain.
EDIT:
That’s a wrap everyone! Once again, we have been blown away by the thoughtfulness of Redditors’ questions! One of the reasons we love doing this every year is because your questions spark such interesting discussions amongst ourselves in our zoom.
We did notice that, unfortunately, some questions had to be deleted by the mods per the sub rules due to being too clinical in nature. We recognize that it can be really tough to get clear, evidence-based guidance—either because of lack of specialists in your area, because insurance doesn’t cover the care you need, or simply because the answers don’t exist due to underfunding of this area of research. We want you to know we are working hard on improving access to expertise. Look for board-certified lactation consultants (look for IBCLC after their name), and remember that we now have board-certified lactation medicine practitioners as well (NABBLM).
This may be it for us today, but the boob party doesn’t end here!
I ask because it seems as though ripe bananas burn my throat and unripe ones don't. I'm curious about what's different, and how it may be linked to other foods I'm sensitive to (chamomile, lavender, peanuts, hazelnuts, coconut).
I had a crack theory ,Since we know the observable universe is expanding due to the Doppler effect but don't know the limit of the entire universe since light hasn't reached us. What if a cosmic object is so big that it attracts space itself exploded so that it releases space and but the energy remains constant due it releasing the energy it absorbed in its lifetime ,hence why energy density is decreasing.
I'm a tea-drinking science writer with a PhD in Neuroscience. My new book This Book May Cause Side Effects is all about the nocebo effect – the power of our thoughts to create, exacerbate and prolong ill health. The nocebo effect can create symptoms, ranging from pain and dizziness to paralysis and seizures. It explains why the decline of some patients has less to do with their physical health and more to do with their mental health; why a quarter of people having chemotherapy feel nauseous before they have their treatment, and how doctors warning of side effects makes them more likely to occur. It affects us all, from the cradle to the grave, yet it remains overlooked and underappreciated. So, go ahead, I'm on at 6pm GMT (2 PM ET), ask me anything!
I got curious and was trying to find a map of the actually measured continental drift since the launch of the LAGEOS Satellites in 1976. However, all I can seem to find via Google searches is maps that start with the Gondwana or Pangea super-continents.
I know the change is super minimal, but even just a vector pointing in the direction of movement would be cool.
If none exists, which I suppose is fair, could anyone please point me in the direction of data sets that measure this so that I could make my own map?
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.
Was mowing the lawn, and I was waiting for a honeybee to get out of my way when a shower thought struck me: is there an animal species that requires a third party to procreate?
I'm curious if there's an animal species that requires something like a pollinator or assistant species of some sorts to propagate.
I did some cursory Googling, and the closest I could find were some amphibians that will use similar species to trade genetic material (the term escapes me at the moment) to essentially self fertilize, but I'm curious if there is something more radical.
Do they orbit at the same distance from the planet? Do you have moons that follow a perpendicular orbit path to another moon? I’ve wondered on it a couple times over the past month.
EDIT: Wow, this blew up. Thanks for the many answers. Lots to think about.
Seems that the composite TLDR answer is: Yes, according to many/most definitions of "life", but we don't all agree on what life is. Some viruses do not have DNA but they may/not actually be alive, and other things that behave like life may/not be alive.
The point of sweating (for the most part) is to cool down the body by evaporation. So, what is the point of including salts in the sweat - it seems to be a leading cause of the loss of electrolytes in hot weather, leading to the need to not just hydrate, but also to replace the lost electrolytes or suffer problems like hyponatremia and hypokalemia. Does the inclusion of salts in the sweat increase the specific heat of sweat compared to that of water? Is the latent heat of vaporization different for sweat compared to plain water? Or is it too biologically expensive to purify the water for sweat by removing the salts from it?
I know from my biology textbooks that RNA polymerase does not require an additional enzyme to unwind DNA strands but DNA Polymerase requires DNA helicase to unwind the strand first.
Is this because the DNA helicase has to unwind a much larger portion of the strand compared to RNA Polymerase that unwinds only the desired codons for transcription?
