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Thursday, October 3, 2019

What plesiomorphic (ancestral) traits of our common ancestor have humans retained but chimpanzees and bonobos have lost?

What plesiomorphic (ancestral) traits of our common ancestor have humans retained but chimpanzees and bonobos have lost?


What plesiomorphic (ancestral) traits of our common ancestor have humans retained but chimpanzees and bonobos have lost?

Posted: 02 Oct 2019 08:20 AM PDT

Is there a theoretical limit to how large a star could be, and what are the limiting factors? What about black holes?

Posted: 02 Oct 2019 09:39 PM PDT

How do we realistically measure distances to stars outside of the milky way and how do we prove universal expansion?

Posted: 03 Oct 2019 01:05 AM PDT

I understand the parallax method, but how can that be trusted when we don't know the speeds of the objects we measure or the speeds of the objects we are measuring against. I also know the speed we orbit our Galaxy, and the speed we orbit the sun. I dismiss the speed of Earth's rotation for the sake of the question and I also dismiss the fact that orbits aren't round but rather more like a spirograph. How do we measure distance to a star with any kind of accuracy whatsoever, when were moving so fast inside of two different systems, and we don't know the speed the Galaxy it's in is moving, or it's rotational speed, no do we know the speed that star is orbiting it's Galaxy? Please help me understand this.

submitted by /u/gkitchens1
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When electrons leap from one orbit to the next are they in between orbits ?

Posted: 02 Oct 2019 05:39 PM PDT

Electrons can only move around certain orbits around a nucleus. If they are agitated (or the opposite) they leap from one orbit to another.

When they move from one orbit to the next to the neutrons exist between orbits while they move? Or do they pop out from one orbit and reappear at the next without moving through space ?

submitted by /u/Captain_Resist
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Does technology inflame our political polarization?

Posted: 02 Oct 2019 10:00 AM PDT

With technological advancement comes increased complexity. Does ones availability to information increase confirmation bias, therefore, leading to amplified polarization of beliefs, values, and mores? Especially evident in today's politics, where it seems more and more difficult for people to compromise.

submitted by /u/akobylski1
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Does density of a substance change discontinuously at its melting point?

Posted: 02 Oct 2019 04:42 PM PDT

Does the density as a function of temperature for a pure substance change discontinuously at its melting point? Or does it merely change very fast but nonetheless continuously.

For example, wikipedia says that mercury changes from a solid density of 13.69 g/cm^3 to a liquid density of 14.184 g/cm^3 at its melting point of -38.83 degrees C (https://en.wikipedia.org/wiki/Mercury_(element))). But if I had a super precise heat control that could let me control the temperature down to hundredths of a mK if necessary (and plenty of time to let the sample fully equilibrate), could I get a mercury sample of, say, 13.9 g/cm^3?

I had always thought of density as changing discontinuously during melting, but I realize now that at least some other phase change properties are not totally discontinuous even when we may think of them that way. Electrical resistance, for instance, is not totally discontinuous when undergoing a superconductivity phase change, but instead transitions rapidly over a few mK. This is even the basis of very sensitive thermometers called "Transition Edge Sensors (TES)" (http://web.mit.edu/figueroagroup/ucal/ucal_tes/). See especially the figure http://web.mit.edu/figueroagroup/ucal/ucal_tes/files/page14_1.png

So does density during melting behave like electrical resistance during super conductivity transition (IE changing fast but nonetheless continuously with temperature)? Or is it truly discontinuous, with no possibility of achieving a density between the two transition values, regardless of how finely one can control the temperature?

submitted by /u/thernometer
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Can we remove too much carbon from the atmosphere?

Posted: 02 Oct 2019 07:08 PM PDT

Imagine an alternate universe where we are just as technologically advanced as we are now. The only difference is that we are kind of 'reset' at a normal level of carbon in the atmosphere. We discover a new technology that actually removes carbon from the atmosphere. Being how are, we use it veraciously across the entire globe.

Is it possible to have kind-of the opposite problem we have now where too much carbon is being removed from instead of added into the atmosphere? If so, what would be happening to our planet if we did remove large amounts of carbon and put is in a net negative from 'normal'?

submitted by /u/dsw1088
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What's actually in space?

Posted: 02 Oct 2019 07:08 PM PDT

Are there anything in the so called empty space if interplanetary or interstellar space? If so what is it and how did it get there?

submitted by /u/evanerfbdgcn
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Does the orientation of the rotation the accretion disk in a Super Massive black hole match the orientation of the spin of the galaxy itself? And in case of quasars?

Posted: 02 Oct 2019 12:18 PM PDT

Is there a relationship between how many babies are born to a member of a species and their chance of living to reproductive age?

Posted: 02 Oct 2019 01:53 PM PDT

I remember hearing that the less likely an animal is to make it to age of reproduction the more babies are born to a female of that species. However I've been unable to find information on this since I heard it. Is this true?

submitted by /u/clocks212
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Why do Iron fillings highlight the field lines of a magnet?

Posted: 02 Oct 2019 01:00 PM PDT

I understand that there is a magnetic field surrounding a bar magnet and they make a torus shape. And that the iron filings are showing that when we sprinkle them over the top.

But why do the iron filings display them as lines? I thought they would be a somewhat smooth distribution.

Is it some sort of frictional mechanism with the filings and the paper maybe?

submitted by /u/tip-top-honky-konk
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Is it possible to have a non-gaseous planet with permanent storms like Jupiter? And what would the conditions have to be for that to happen?

Posted: 02 Oct 2019 07:45 AM PDT

Were there more forests in Western Texas, Nevada, and Arizona before Europeans arrived, or has the landscape stayed pretty much the same?

Posted: 02 Oct 2019 11:53 AM PDT

Is it possible for the pentose sugars, ribose and deoxyribose to form a bond with each other?

Posted: 02 Oct 2019 12:57 PM PDT

I understand that hexoses can (glucose + fructose, glucose + galactose). So then what about ribose + deoxyribose?

submitted by /u/Dakmury
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What is the biomechanical significance of "bird hips" in dinosaurs?

Posted: 02 Oct 2019 10:05 AM PDT

It's my understanding that the dinosaur clade is grouped together by their hip-bone structure which is similar to modern day birds. This seems a bit odd since dinosaurs probably did a bit more walking and running than most species of bird. The only exceptions would be ostriches, cassowaries, and extinct terror birds. Even then they were bipedal which is characteristic of only a segment of dinosaur species. What made this trait so significant it endured millions of years of natural selection?

submitted by /u/Humble_Skeleton_13
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Why is the allergic response different than the immune response?

Posted: 02 Oct 2019 09:17 AM PDT

In my physiology class, like most classes, we're learning that the allergic response is a hypersensitive response to nonpathogenic antigens. We learn about it as a facet of the immune system. But if it's the immune system? Why isn't it a normal immune response? If it's only for nonpathogens, why is there a response at all?

The symptoms are so different, I can't tell why the allergic response exists at all--it doesn't actually seem to do anything to support the goals of the immune system.

submitted by /u/KittyScholar
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How was the dot product for 4-vectors in Minkowski space derived?

Posted: 02 Oct 2019 05:39 PM PDT

I've asked my TAs and they say that the (+---) metric comes from the fact that c remains the same in all reference frames, but I'm not sure where to follow from that both mathematically and with a scientific explanation.

submitted by /u/_Sunny--
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Are the solutions to a linear second order differential equation near the repeated root "continuous?"

Posted: 02 Oct 2019 11:27 AM PDT

I know that the form of the solution changes when the characteristic polynomial has a repeated root, and that's causing some confusion. For the same set of initial conditions, will infinitesimally varying the constants to or away from sqrt(b2 -4ac)=0 cause x(t) to shift in a continuous way, or is it discontinuous? Physically, it seems like it should be continuous, but the change of form of the solution makes it seem discontinuous.

submitted by /u/Platyturtle
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Is glucose just naturally damaging? Why is high blood sugar bad? Can normal people have blood sugar issues?

Posted: 02 Oct 2019 08:12 AM PDT

I've done a little reading about diabetes and it got me asking some questions. It seems like there's a consensus that high blood glucose levels damage your body. Does glucose always cause damage? Is there a level below which glucose doesn't cause damage? Is it more of an optimum level where you have a trade off between damage and body energy (which obviously affects tons of things)? Can spikes in non diabetic people, from drinking a bunch of soda for example, cause small amounts of damage?

submitted by /u/kittenTakeover
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How did Earth's tectonic plates form and why do they move?

Posted: 02 Oct 2019 07:04 AM PDT

To what degree does the pronunciation of a word determine it's potential obscenity/slur-ability?

Posted: 02 Oct 2019 02:46 PM PDT

The average word is just about as exciting as the dictionary makes it out to be, while a chosen few are singularly responsible for generations of smack-downs, tears, persuasion and death--since they came to be.

Just say it. "Fuck." It's one of life's real treasures.

Is it because it physically feels good to say? Do the rules change depending on the language?

submitted by /u/LampsLookingatyou
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Would a sodium ion have the same properties when in an ionic compound and just by itself?

Posted: 02 Oct 2019 02:44 PM PDT

So because ionic bond is caused by the oppositely charged particles attracting, does this mean that in an ionic compound all the ions would still retain their original ionic properties?

submitted by /u/saynotomarijuanaweed
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Wednesday, October 2, 2019

In a desert, what is under all of the sand?

In a desert, what is under all of the sand?


In a desert, what is under all of the sand?

Posted: 01 Oct 2019 11:50 AM PDT

I've always wondered, in stereotypical deserts with plentiful sand dunes, how deep does the sand go? And what's under the sand? Water? Dirt? Stone?

submitted by /u/sloposaurus
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Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology

Posted: 02 Oct 2019 08:08 AM PDT

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.

If you would like to become a member of the AskScience panel, please refer to the information provided here.

Past AskAnythingWednesday posts can be found here.

Ask away!

submitted by /u/AutoModerator
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What is the most primitive organism that can get addicted to drugs?

Posted: 01 Oct 2019 08:06 PM PDT

From the perspective of an outside observer, when does the Schwarzschild radius of a black hole grows?

Posted: 01 Oct 2019 06:51 PM PDT

As I understand, from the perspective of an outside observer, an object falling into a black hole approaches its event horizon asymptotically and takes infinite time to actually reach it. So, when would the observer be able to register the Schwarzschild radius of the black hole increase, if, as far as they're concerned, the object never crosses the horizon?

Would it be the moment when the object gets close enough to the "old" horizon to be encompassed by a "new" horizon that accounts for the objects mass?

submitted by /u/CommanderWobbly
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When the Earth and Mars are positioned 180° across from each-other with the Sun in-between them, are we able to recieve data from equipment on Mars or does the Sun form a sort of radio "dead zone"?

Posted: 01 Oct 2019 06:09 PM PDT

Can a container ship be powered by a nuclear reactor rather than the gasoline equivalent of 50 million cars?

Posted: 01 Oct 2019 02:03 PM PDT

Do identical twins grow their teeth the same way?

Posted: 01 Oct 2019 06:48 PM PDT

I guess what I'm trying to ask is if teeth growing is genetic? Like would identical twins both have the same "crookedness" of teeth after 20 years if neither got braces?

submitted by /u/alosia
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Why can't you be focused throughout the whole day?

Posted: 01 Oct 2019 11:58 AM PDT

Why cant you start focusing when you wake up and stay so till you go to sleep? When I try to do this, I get tired and I make mistakes I normally don't do. Why does this happen?

submitted by /u/Myzel394
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are electron current and "hole current" (positive) different things?

Posted: 01 Oct 2019 02:41 PM PDT

I learned a while ago that electric current is caused by negatively charged electrons moving through a conductor, but conventional current is modeled as positively charged "holes" (the absence of an electron) moving in the opposite direction in order to make calculations easier. I always thought an electron moving in one direction was the exact same thing as a hole moving in the opposite direction, but recently i read a physics textbook that said "most conductors exhibit electron current, but some, including zinc and aluminum, exhibit hole current", which implies that they are different things. Is the textbook correct? If so, what's the difference between electron and hole current?

submitted by /u/Valence55
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Why don't celestial objects rotating around other celestial bodies (like the earth, rotating around the sun) end up colliding with the thing they're orbiting (like a marble, ending up in the center of a sloped surface)?

Posted: 01 Oct 2019 01:05 PM PDT

I ask because i just saw some images of how gravity actually works, with gravity wells surrounding massive objects. So i got to wonder how something like the earth, doesn't eventually fall into the gravity-well of the sun?

submitted by /u/benisbrother
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[Medicine]what is it about red meat that makes it carcinogen?

Posted: 01 Oct 2019 02:32 PM PDT

What factors determine the lifespan of an animal?

Posted: 01 Oct 2019 07:49 AM PDT

I know the question seems stupid but I really am curious why other mammals with similar size to humans live so much less if compared to us. We are descendants of apes but what actually caused human lifespan to reach about twice the lifespan of apes and other mammals.

Edit: I would like to clarify that I understand modern science and medicines have helped humans a lot, but I am just trying to put on a hypothetical situation here. Okay, lets say a human stays infection/disease free and is supposed to die only by natural causes, he is most probably supposed to survive till 70 at least as per my understanding, but put the same scenario on any other animal and they still would pass away at a much earlier stage. What is the cause behind that?

submitted by /u/mrgarlicpickle
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Why does the current that flows through a semiconductor increase nonlinearly as a reaction to an increasing temperature?

Posted: 01 Oct 2019 10:28 PM PDT

We're learning about semiconductors in school, and there's one thing I don't understand:

We graphed the amount of current that is flowing through the semiconductor over the temperature the it's exposed to.

With linearly increasing heat, the current increased in a curve.

This doesn't make sense to me because we learned in class, that because of the increasing heat, more electrons can free themselves from their bonds and start flowing, which allows more current to pass through. With this explanation, I would think that if there is double the amount of heat, the reaction of the semiconductor would be to let double as many electrons flow freely. This would result in a linearly growing line in the above mentioned graph.

This is not the case, and that's what I'm confused about.

(Thx in advance, and srry if I didn't explain it very well.)

submitted by /u/niktedig
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Magnitude or depth, which is more important to strength of an earthquake?

Posted: 01 Oct 2019 10:08 AM PDT

My friend and I are arguing about what more important when thinking about the strength of an earthquake, depth or magnitude. I think the magnitude of the earthquake at your location is more critical to understand the strength of the earthquake.

Could someone help us understand this stuff?

submitted by /u/Sontlux
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How do we know how much of each cannabinoid (CBD, THC) is in a cannabis product?

Posted: 01 Oct 2019 01:10 PM PDT

My food analysis professor stated in class that there is no official method for measuring cannabinoid content in products as of now. But I know that CBD products (at least the legal CBD products in my state) often say the CBD content. This has me wondering how they are finding this out, is it just any random unofficial test they come up with?

submitted by /u/EPIC-8970
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How does the value of a field propagate? (physics)

Posted: 01 Oct 2019 07:46 AM PDT

In the entry level physics courses when you have a charged particle you are told to put a 'test charge' somewhere in your problem (the field) and evaluate what the forces should be if you actually had a test charge in that position. My understanding is that if you did have a test charge in that location that there would be an exchange of force carriers (photons in this particular field) between the source and the test charges. This would be how they interact and determine the effect they have on one another.

What I'm curious about is how the field exists without a test charge. The way I have always thought about it is that there is a 'sea' of virtual particles propagating out from the source charge throughout the entire region of that field (which I guess is infinite?) and those virtual particles interacting with one another carry the 'field value' for any particular point. But the idea of infinite virtual particles propagating for everything that projects a field feels intuitively wrong....

So that is my question: How does a point in a field, electromagnetic or otherwise, 'know' what value to evaluate to be. Sea of virtual particles, or is the field an object in itself and does the field just update itself in an outwardly moving wave from each source particle that exists inside of it? Or something else?

submitted by /u/charmquark237
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Do Merkel cells have hemidesmosomes?

Posted: 01 Oct 2019 12:01 PM PDT

Hi everyone! Just a stressed med student here :/

Can anyone let me know if Merkel cells have hemidesmosomes? I know that they have desmosomes that connect them to keratinocytes, but I'm not sure if the Merkel cells themselves have hemidesmosomes that connect them to the basement membrane.

Thanks!!

submitted by /u/PatateEndormie
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What is the difference between Constant-Mean-Curvature surfaces and Minimal surfaces?

Posted: 01 Oct 2019 10:58 AM PDT

How does TMJ happen? (The cramp in your jaw when you yawn really big)

Posted: 01 Oct 2019 01:12 AM PDT

So I understand why it's caused and how to deal with, but I just want to know what specifically happens with your muscles/tendons that makes it so painful. It feels like they stretch too far and get stuck rather than contracting back to a normal position. Any explanation or visual would be greatly appreciated.

submitted by /u/ParkerR_93
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How do you feed someone in a coma?

Posted: 30 Sep 2019 06:18 PM PDT

Tuesday, October 1, 2019

If electrons behave as waves when they’re not observed and behave as particles when observed at microscopic scale, how can they behave as waves observed at eye scale? (Young experiment)

If electrons behave as waves when they’re not observed and behave as particles when observed at microscopic scale, how can they behave as waves observed at eye scale? (Young experiment)


If electrons behave as waves when they’re not observed and behave as particles when observed at microscopic scale, how can they behave as waves observed at eye scale? (Young experiment)

Posted: 30 Sep 2019 11:39 AM PDT

What is the difference between anti matter and dark matter?

Posted: 30 Sep 2019 10:06 PM PDT

Why is the critical damping coefficient b=2sqrt(km) in a damped oscillator?

Posted: 30 Sep 2019 09:40 PM PDT

Specifically, for the equation mx'' +bx' +kx = 0. I get that b=2sqrt(km) makes the solution of the repeated root form and that it "feels" right, but I haven't been able to prove that this value of b minimizes x(t) (makes it decay fastest) or find a proof anywhere else.

submitted by /u/Platyturtle
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Do hurricanes affect aquatic life?

Posted: 30 Sep 2019 10:29 AM PDT

Their damage to land and its lifeforms is uh.... well very obvious to say the least. But does a category 5 hurricane have dramatic effects on the aquatic life underneath it? In regards to shallow coast lines as well as while it is out in the open ocean?

Thanks!

submitted by /u/azndude07
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How is it possible to isolate a single atom of an element and hold it stationary? How is it done?

Posted: 30 Sep 2019 12:40 PM PDT

I recently came across this photo of a single strontium atom, not a real atom but as they put it,

The atom is being illuminated by a blue-violet laser. The energy from the laser causes the atom to emit photons which Nadlinger could capture on camera using a long exposure

https://www.sciencealert.com/this-mind-blowing-photo-of-a-single-trapped-atom-won-a-prize-this-year

So, I was wondering how were they able to separate one atom from, let's say block of solid strontium? And then slow it down so that it can be easily observed?

submitted by /u/SS2602
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What is happening in the brain when we try and 'think hard'?

Posted: 30 Sep 2019 01:30 AM PDT

When did the Deinonychus, and other theropods, really live?

Posted: 30 Sep 2019 09:45 AM PDT

I'm doing an infographic project for my design class where I compare some notable theropods to their pop culture counterpart; the velociraptors from Jurassic Park.

When trying to find fact about these animals, I get conflicting information. Specifically with the time period in which the Deinonychus lived, the Natural History Museum says 120-110 million years ago, Encyclopedia Britannica says 145-99 mya, and Wikipedia (yes I know) says 115-108 mya. There are also conflicting sources on it's adult size being 11.4 feet, or 8 feet.

I've encountered this issue with the Utahraptor and Dakotaraptor as well, but not so much with the Velociraptor. I want to be as accurate as possible, but I don't know where to look, or what sources are credible.

I'd really appreciate the help, thanks.

submitted by /u/Raptorhythm
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How do they hold together skeletons of large animals at museums?

Posted: 30 Sep 2019 02:54 AM PDT

So my school just finished preserving this massive whale skeleton (see post history) and I'm sitting here studying and start to wonder how it's all held together. Obviously there is significant weight to the vertebrae and head. I know there are a few attachment points when they're hung up but it doesn't seem like enough. I'm just wondering how it's all held together but Google is coming up dry!

submitted by /u/mr627990
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Since 1986, what new techniques have we adapted to cope up with a nuclear disaster like Chernobyl?

Posted: 30 Sep 2019 12:33 AM PDT

What is the scientific name for tendons?

Posted: 30 Sep 2019 11:23 AM PDT