[Intro] Michael: Ladies and gentlemen, boys and girls, welcome to SciShow Quiz Show, the only quiz show where at six feet tall, I'm the shortest one on stage. I'm your host, Michael Aranda, and today we have a tiebreaker, because in 2014, you two faced off and Reid won.

Hank: Wow.

Reid: Really? I don't remember that.

Michael: And then in 2015, you guys faced off and Hank won.

Hank: I don't remember anything. [Reid laughing]
Michael: And today--

Hank: We're gonna-- And then, we'll never do it again. Best two out of three.

Michael: Today, we are going to break the tie. As a special thank you to our supporters on Patreon, we selected two of you at random to win the prizes that Hank and Reid will earn for you today. Hank, you are competing on behalf of Lucia Yates.

Hank: Hello, Lucia. Michael: Reid, you're playing for Bella Nash.

Reid: Bella Nash! Hi, Bella.

Hank: Or, possibly "Lu-chi-a"

Michael: Well--

Caitlin: [Talking off camera] It's listed as Lucia.

Reid: We checked, we checked.

Stefan: Today, regardless of how Hank and Reid do, both Lucia and Bella will be taking home the signed cards from the final round with our contestants final guesses and wagers on them. The winner will receive the "I Won SciShow Quiz Show" pin, but the loser will get the ultra rare "I Lost SciShow Quiz Show" pin. And, the winner will also take home some secret SciShow swag from dftba.com. Back to you.

Michael: So, both of you start off with 1,000 SciShow Bucks.

Hank: Then, I'm just going to leave right now.

Reid: Yeah, no kidding actually.

Hank: Probably the best, best thing to do.

Reid: I bet one dollar.

Michael: Each time, each time you answer a question correctly, you'll get a hundred points. If you answer incorrectly, you lose a hundred points.

Reid: OK.

Michael: You guys ready for round one?

Hank: Yes, sir. Michael: Round One is about forensics.

Reid: [Quietly] You have to keep hands back.

Hank: OK. Michael: There are lot of ways to identify people besides looking at their DNA, and for a long time forensic scientists have used unique patterns in human bodies as conclusive evidence to identify and convict criminals. 

Hank: Mhmm.

Michael: But over the years, scientists have realized that some of these patterns aren't quite as unique as we thought they were. So, which of these techniques is no longer considered a reliable way to identify someone?

Michael: Is it vein analysis, retina scans, tooth print analysis, or fingerprint analysis? [Chime]

Hank: I'm gonna go with tooth print analysis, Michael. Cause that seems pretty arbitrary to me.

Michael: Well, the table turned green, so you are correct.

Reid: Aw.

Hank: I mean, sometimes your teeth change, too.

Reid: Yeah, plus it's like--

Hank: Mine have been floating around.

Reid: It's very subtle.

Hank: Yeah, right.

Reid: Like, a subtle thing, whereas, like veins, you could get like down to the little, the wiggly ones.

Hank: Right, right, right. If, like, I, if I bite you, like, what if I, what if I have like have, like, just, like, am sort of twisting around or doing it a bunch or like?

Reid: Or have like a, you know, corn husk stuck in there.

Hank: Yeah! A corn husk.

Reid: You never know. Corn husk killer!

Michael: For decades, bite mark comparisons have been used to both identify and convict people. It was famously used to convict serial killer Ted Bundy in 1979. But, in recent years, investigators have gone back over old cases, often using new technology to analyze DNA evidence, and they're finding that bite mark analysis isn't as reliable as they once thought. Dozens of people who were convicted based on their teeth have now been exonerated. It turns out that it's pretty common for people's teeth to be arranged in similar ways, and it seems like human skin isn't as good as we thought at preserving the shape of bite marks. Vein analysis and retina scans, meanwhile, are still considered reliable ways to identify someone, though, they're generally used in security and biometrics, rather than in forensic investigation. These techniques involve looking at the unique tangle of blood vessels in a person's forearms and retinas, respectively. Fingerprints are still considered unique, too. Comparisons can be wrong in very rare cases, but that's generally because of the computer or person doing the analysis made a mistake. Speaking of fingerprinting--

Hank: All right.

Michael: Even though fingerprints are one of the most useful ways to analyze a crime scene, it's not always easy to see them. So, forensic scientists have special techniques to help them develop these so-called latent fingerprints. One method involves a common household item that bonds to the molecules left behind in the fingerprints. Which household item is used to do this? Is it cooking spray, super glue, ammonia, or witch hazel?

[Chime] Reid: I'm gonna go for super glue.

Hank: I was going to go for super glue, too. Dang it! Dang it!

Michael: You are correct, sir.

Hank: Should have hit harder-- faster.

Reid: Yeah, that was in, uh, Beverly Hills Cop 2, I believe. They used those special skills.

Michael: There are lots of different components to a fingerprint. There's sweat plus all the stuff in the oils left behind by your fingers. Those oils contain amino acids, and that's where the super glue method comes in handy. Super glue is made of cyanoacrylate, which, as you'd probably guess, is very good at bonding to things, including the amino acids in fingerprints. But, you can't just smear it onto surfaces and expect fingerprints to show up. To develop fingerprints, investigators set up a little chamber where they boil cyanoacrylate and let the gas surround the object they're trying to get prints from. When the molecules in the gas bond with amino acids, they form a white coating on the fingerprint's ridges. Then, all investigators have to do is take a picture of the developed print.

We're moving on to Round Two, which is about the human body, and the point values have gone from 100 to 200.

Hank: All right.

Reid: Deal. I have one of those.

Hank: I do, too. I know, I like have my whole life with a human body.

Michael: Inside a human body.

Reid: Right here.

Hank: Yeah. Michael: Some of the simplest things to study in genetics are Mendelain traits, or characteristics that are controlled by just one gene. A classic example would be eye colors in fruit flies. A fruit fly's eyes will be either black or red depending on which version of a single gene they have. You'll often hear people talk about examples of Mendelian traits in humans, but a lot of those examples are actually just myths.

Hank: We're pretty complicated.

Michael: Which of the following characteristics in humans is actually controlled by one single gene.

Hank: OK. [Tapping on table] Michael: Is it whether you're lactose-intolerant, whether you can roll your tongue, whether your earlobes are attached, or whether you can bend your thumb backwards? [Chime]

Hank: I'm gonna go with earlobes, Michael.

Michael: Incorrect!

Hank: Ah!

Reid: Oh, man. Um, what was the first one again?

Michael: Lactose-intolerant, roll your tongue, thumb backwards.

Reid: I kind of like lactose-intolerant. I would go for lactose-intolerant.

Michael: OK, you are correct!

Hank: Gah!

Reid: Ha! Look at that green, Hank Green.

Hank: Oh, god. I'm so far behind now. I'm 400 behind.

Michael: I haven't--- what's the score?

Caitlin: [Off camera] 1300 to 900.

Michael: Oh. You were doing math this whole time, too?

Hank: Well...

Michael: How can you pay attention to the question if you're doing math at the same time?

Reid: This is science.

Michael: Biologist use to that attached earlobes, the ability to roll your tongue, and the ability to bend your thumb backwards were all Mendelian traits. But, studies have shown that the truth is more complicated than that and there are more genes involve, no matter what you might have been taught in your introductory biology class. On the other hand, the ability to drink milk as an adult is the result of a single mutation that started around 8,000 years ago in the area we now call Turkey. That mutation was useful, because it gave people a new food source and it spread through the population so now 35 percent of humans can drink milk.

OK, our next question. People faint when the blood pressure in their brain gets too low, and all kinds of conditions can cause this sort of low blood pressure, including things that affect the autonomic nervous system, which helps controls things like your heart rate and breathing.

Reid: Mmhm.

Michael: With that in mind, which of these is not a cause of fainting? Looking at art, peeing, taking a cold shower, or brushing your hair?

Hank: I'm gonna let Reid go first, cause I really, there's no other way for me to catch up. [Laughing]

Reid: Um-- [Chime]

Reid: --I'm gonna go for looking at art. That seems silly to me.

Hank: Yeah.

Michael: That is incorrect.

Reid: Oh. Michael: That's minus 200 points for Reid.

Hank: All right, well I wasn't paying attention at all. [Reid laughs]

Hank: Uh, I bet it's-- [Chime]

Hank: --brushing your hair. Gah!

Michael: Incorrect!

Reid: Ah! [Whistles] So I know that peeing would be one.

Hank: Yeah. I gave--

Michael: So, the answer was taking a cold shower.

Reid: Taking a cold shower, OK.

Hank: Taking a hot shower, I bet, will make you faint some times.

Reid: It could.

Hank: Cause I paint while feeing all the time.

Michael: [snickers] You paint while feeing?

Hank: Yeah. I get paid to paint.

Michael: Yup. Fainting from viewing art is a real thing. It's known as Stendhal Syndrome, and it's psychosomatic, meaning that the symptoms are influenced by the person's thoughts. When people with Stendhal Syndrome see collections of art that they think is beautiful, they experience symptoms like dizziness, and disorientation, and they sometimes faint. Fainting during or after urination is know as micturition syncope.

Michael: It's not totally understood, but it's thought to be caused by a sudden drop in blood pressure, either from standing up to pee from lying down or from emptying an especially full bladder. Hair-grooming syncope is rare and usually affects children. It's thought to happen because the brush or comb is stimulating nerves on the child's head, or because they're positioning their neck in a way that affects their blood vessels and therefore blood flow to the brain. People do sometimes faint from hot showers, which can lower blood pressure, but cold showers don't do that.

So, last question in this section.

Reid: OK.

Michael: Scientists used to think that humans could only see visible light. That's obviously why they call it visible light. But, they recently learned that under certain conditions, infrared light can actually trigger the light detecting cells in the human eye. What are these conditions? When the light beam is very wide, when the light beam is very narrow, when the light includes both infrared and ultraviolet, or when the light comes in short bursts? [Chime]

Reid: I'm gonna go for short bursts.

Hank: Get it wrong.

Michael: You're correct, sir!

Hank: Dang it!

Reid: Yeah!

Hank: Oh my god! I'm not gonna- I'm never gonna catch up.

Reid: You can some day, honey. It's OK. I mean this is just our tiebreaker, and, um, somebody's getting broke, I'm just saying.

Hank: OK, uh, don't wanna, oh. I'll see ya in 2018.

[Reid laughing]

Michael: This phenomenon was actually discovered by accident in 2014. Researchers were working with an infrared laser, and they knew they weren't supposed to be able to see its light but they sometimes saw flashes of green. So, they did what scientists do when they don't understand something, they decided to study it. When they experimented with the laser, they found out that when it sent out pulses of infrared light really close together, it triggered both mouse and human retina cells. Normally photons of infrared light wouldn't have enough energy to trigger these cells, but the researchers realized that when the pulses were very short, the cells would absorb two photons at once, which activated them and sent a signal to the brain. So, that's why they were able to see the infrared light.

Hank: Oh. I can barely, I can--

Reid: I'm sorry, wait, is that almost twice as much? I'm just checking, almost twice as much? OK, good.

Hank: I can barely catch you.

Reid: hehehe, you might be able to. I might get it wrong.

Hank: I can catch you.

Michael: So at this point, Hank you have 700 points, Reid you have 1300 points.

Reid: YES!

Michael: We've reached the point where you guys are gonna bet on your answer to the next question. I can tell you that the next question is about materials science.

Hank: I didn't wait, (whispers) just bet.

Reid: What is materials science? Wait, what, are we supposed to show what we are betting now?

Hank: No, you're not.

Reid: Ok.

Hank: And I did.

Michael: While you figure out how much you're gonna bet.

Hank: I'm psyching you out.

Reid: Materials science?!

Michael: We're gonna go to commercial break. Welcome back! Are you guys ready to hear the question?

Reid: (laughing) Yes.

Michael: Ok, pykrete is a material made out of 14% sawdust and 86% ice. It's useful because it melts really slowly and it's super strong, but pykrete was originally invented for a very specific purpose, what was it?

Hank and Reid: Ooh...

Michael: Preserve food, provide housing during expeditions in Antarctica, build a bridge, or build a boat?

Reid: Do we just write it down? Or just say it?

Michael: You just write it down.

Reid: (singing) Ok cause I actually know this one hahaha! Cause I am awesome hahaha! Oh, are you not done yet Hank? Cause I am, cause I knew this one.

Hank: I just, I changed my answer cause I think I know what Reid wrote, and if he gets it right it doesn't matter so I'm guessing that he's wrong about thinking that he's right.

Reid: Fool!

Hank: And going with another answer.

Reid: Well I know it was used for this at some point, I don't know if it was the original purpose.

Michael: He seems pretty confident.

Reid: I always seem confident, it's called fake it till you make it.

Hank: But now I am making him.. yes yes.

Michael: Ok, reveal your answers.

Hank: Build a houses!

Reid: Build a boats! It's on a boat! Tell me I'm right.

Michael: Reid is correct.

Reid: YES!! Aw yes! Can we get green really quick? Yeah, you see how green that is? Who's the green brother now huh?

Michael: oooo hahha

Michael: Back in World War 2, the British navy wanted to build an unsinkable aircraft carrier, and a man named Geoffrey Pyke was looking for innovative ways to do it. A one thousand ton ship made of ice was built in Canada based on his ideas, and it worked pretty well but it wasn't quite strong enough. Then Pyke came across a report that said ice was stronger when it was mixed with little bits of wood. He started experimenting with combining different proportions of ice and wood.

And that's how pykrete was born. The material wasn't too expensive, it was stronger than concrete, it was basically bulletproof and with a little built-in refrigeration, it wouldn't melt in the ocean. As promising as the project seemed, the navy never ended up building a pykrete aircraft carrier, there was still some kinks to work out with the design and the project wasn't a priority.

But for a while there, the world almost had a giant ice boat.

Hank: Well, you beat my zero points!

Reid: (laughing) I really did! By how many exactly though? Can we just rub it in really quick? 1401 points!

Hank: to zero.

Reid: to zero.

Hank: aw, I can't believe Reid beat me.

Reid: Ah I believe its twice now? Is that twice? Can we just?

Hank: Yes! It's best two out of three, you are now the best. We can all agree.

Reid: For now!

Hank: I'll get you a shirt that says 'the best'!

Reid: Can you really actually? I'd like that.

Hank: I'm sure you already have one.

Reid: I don't, no, I just write it on everything I wear, I helps to keep me from being sad.

Michael: Well! And with that, thank you for joining us for this Scishow Quiz Show, and thank you Lucia Yeats and Bella Nash for your support on Patreon and thanks to all of our patrons on Patreon who make this show possible. If you'd like to help us make episodes like this, you can go to patreon.com/scishow and forget to go to youtube.com/scishow and subscribe!