Learn about whether you lose more heat through your head; red blood cells in immunity; and Venus’ non-existent oceans. You Don’t Lose The Most Heat Through Your Head by Ashley Hamer Noreen. (2011, June). You Don’t Lose Heat Faster Through Your Head than Other Parts of Your Body. Today I Found Out. http://www.todayifoundout.com/index.php/2011/06/you-dont-lose-heat-faster-through-your-head-than-other-parts-of-your-body/ Sample, I. (2008, December 18). Scientists debunk the myth that you lose most heat through your head. The Guardian; The Guardian. https://www.theguardian.com/science/2008/dec/17/medicalresearch-humanbehaviour Red blood cells might play a big role in immunity by Cameron Duke Lam, L. K. M., Murphy, S., Kokkinaki, D., Venosa, A., Sherrill-Mix, S., Casu, C., Rivella, S., Weiner, A., Park, J., Shin, S., Vaughan, A. E., Hahn, B. H., Odom John, A. R., Meyer, N. J., Hunter, C. A., Worthen, G. S., & Mangalmurti, N. S. (2021). DNA binding to TLR9 expressed by red blood cells promotes innate immune activation and anemia. Science Translational Medicine, 13(616). https://doi.org/10.1126/scitranslmed.abj1008 Perelman School of Medicine. (2021, October 20). Study finds red blood cells play significant role in immune system through discovery of DNA-binding capability. Medicalxpress.com; Medical Xpress. https://medicalxpress.com/news/2021-10-red-blood-cells-significant-role.html Contrary to popular belief, Venus probably never had oceans by Briana Brownell Did Venus ever have oceans? (2021, October 13). EurekAlert! https://www.eurekalert.org/news-releases/931214 Turbet, M., Bolmont, E., Chaverot, G., Ehrenreich, D., Leconte, J., & Marcq, E. (2021). Day–night cloud asymmetry prevents early oceans on Venus but not on Earth. Nature, 598(7880), 276–280. https://doi.org/10.1038/s41586-021-03873-w Follow Curiosity Daily on your favorite podcast app to learn something new every day withCody Gough andAshley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Learn about whether you lose more heat through your head; red blood cells in immunity; and Venus’ non-existent oceans.
You Don’t Lose The Most Heat Through Your Head by Ashley Hamer
Red blood cells might play a big role in immunity by Cameron Duke
Contrary to popular belief, Venus probably never had oceans by Briana Brownell
Follow Curiosity Daily on your favorite podcast app to learn something new every day with Cody Gough and Ashley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/heat-through-your-head-red-blood-cell-immunity-venus-oceans
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from Discovery. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about whether you really do lose the most heat through your head; the surprising discovery that red blood cells might play a key role in immunity; and why Venus probably never had oceans after all.
CODY: Let’s satisfy some curiosity.
There are plenty of seasonal myths out there. Things like "cold weather gives you colds" (it doesn't) and "you can't sunburn on a cloudy day" (you certainly can). Well here’s the truth behind another often-repeated myth: you do not, in fact, lose most of your body heat through your head.
This myth probably stemmed from some experiments performed by the U.S. military in the 1950s — not exactly the heyday of scientific rigor. In those studies, researchers dressed volunteers in Arctic survival suits and exposed them to bitterly cold winter weather. Because their heads were the only parts of their bodies left uncovered, that's where they lost most of their heat. Sounds like a good way to conclude that you lose most of your heat through your head, but not so fast: If the volunteers had worn hats and left an equivalent area of their arms or legs uncovered, the same amount of heat would have escaped through those areas.
The reason it feels like more heat escapes through some places than others is that your head, face, neck, and chest are up to five times more sensitive to temperature changes than the rest of your body. By bundling up with a hat and scarf in winter or taking off a ball cap in summer, you feel like you're doing more to change your body temperature than if you were to change other clothing. But in reality, roughly 10 percent of your body heat escapes through your head. That just so happens to be the same amount of your body's surface area that your head makes up. Whether you wear a hat or not, the other clothes you wear play just as much of a role in how hot or cold you feel.
Of course, this isn't to say you should head out on a below-zero winter day with your head bare. The 10 percent of your body heat that escapes through your head isn't nothing, and every bit of bundling helps keep you warmer than you would be otherwise. What I am saying is that you can't just put a hat on and expect to stay warm in a T-shirt. Don’t make me say I told you so.
Your red blood cells have a secret superpower. As if shuttling oxygen from your lungs to the rest of your body wasn’t enough! It turns out that they also help out your immune system. That’s right: It’s not the white blood cells that get all the glory — red blood cells also play a role in immunity. And this was a pretty major revelation for researchers.
When people come down with serious infections like pneumonia, sepsis, or COVID-19, they often become anemic. This means that they start losing red blood cells. That’s kind of weird, since the infection usually doesn’t attack those cells.
So a group of researchers set out to understand why. In their study, they analyzed blood from 100 COVID-19 patients and 50 sepsis patients. They examined the proteins on the outside of their red blood cells and found that they were expressing abnormally high levels of one particular protein: TLR9.
TLR9 is a type of protein called a toll-like receptor, which plays a role in immunity for all sorts of tissues. When bacteria or viruses invade your body, they release genetic material into your bloodstream as free-floating DNA. Toll-like receptors are like fly paper to free-floating DNA. These receptors trigger the production of cytokines, which, in turn, trigger an inflammatory response that helps your body fight off the invader.
TLR9 proteins on red blood cells bind to free-floating DNA too. But their appetites are limited — when they scoop up too much DNA, the cell they’re attached to deforms. This brings an immune cell called a macrophage over to gobble up the cell, DNA and all. The body will make new cells to replace the missing ones, and when it does, it replaces them with cells that have extra TLR9.
The researchers believe that this newly-discovered immune-boosting responsibility might be one of the reasons anemia appears during an infection. The TLR9-bearing red blood cells are hard at work scooping up DNA, dying, and being gobbled up. So a person with an infection has fewer red blood cells to go around.
This knowledge has tons of potentially useful applications. For one, the researchers think that doctors might be able to analyze the DNA bound to red blood cells in a blood sample to find out exactly what pathogen is causing an infection.
And if researchers can tone down TLR9 without affecting other immune cells, they might also be able to treat anemia itself. Either way, we now know that our red blood cells have been working even harder than we thought.
The planet Venus is often used as a cautionary tale for life on Earth. It’s been said that Venus used to have liquid water oceans and a temperate climate, but a runaway greenhouse effect turned it into an unlivable hellscape. But new simulations question that cautionary tale. They say that Venus probably never had oceans in the first place, and our young Earth came alarmingly close to the same fate.
Although Venus is about the same size as Earth, it’s pretty different from our home planet. It has an extremely thick CO2 atmosphere and clouds of sulfuric acid. Its average temperature is much higher than Earth’s, too — over 400 degrees Celsius. And it rotates backwards at an extremely slow rate: just one day for every 500 Earth days.
To find out how Venus got to be this way, astrophysicists used 3D models of the atmosphere that are pretty similar to the ones scientists use to understand the past and future of Earth’s climate. Those models showed that the water vapor on Venus probably never condensed in the atmosphere to make raindrops. In other words, Venus never had rainfall that could accumulate in lakes or oceans. Any water would have existed as steam.
The researchers ran the simulations for Earth too. For a long time, researchers believed that the relatively weak sun radiation early in our planet’s life made us narrowly avoid being an ice world, where temperatures remained so low that all the liquid water turned to solid ice. But the simulations showed the opposite: that Earth narrowly avoided turning into an inhospitable pressure cooker like Venus. If the Earth had been just slightly closer to the sun, or if the sun had been just slightly hotter, oceans probably wouldn’t have formed on our planet either. We would have been a “steam” world instead.
The researchers point out that this new information about Venus is just a stepping stone toward a better understanding of the planet. It’ll take real observations on actual missions to Venus — missions like the three we have planned in the future — to really know whether these simulations are accurate.
But for now, the simulations show how delicate the formation of habitable planets might be in the universe, and add to our understanding of what kinds of planets might have the right conditions for life.
Let’s recap what we learned today to wrap up. Starting with
CODY: Venus probably never had oceans like we once believed. That’s according to computer simulations of the planet’s evolution, which found that water vapor probably never condensed in the atmosphere to make raindrops, so rain never accumulated to form lakes and oceans. Instead, Venus existed as a sort of “steam world.” The simulations also showed that Earth came dangerously close to being a steam world too — if it had been slightly closer to the sun, or if the sun had been slightly hotter, we may have been a Venusian pressure cooker ourselves.
[ad lib optional]
ASHLEY: Today’s writers were Cameron Duke and Briana Brownell.
CODY: Our managing editor is Ashley Hamer, who was also a writer on today’s episode.
ASHLEY: Our producer and audio editor is Cody Gough.
CODY: [AD LIB SOMETHING FUNNY] Join us again tomorrow to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!