- This is me running for my life in a forest as I'm being hunted by an animal specifically trained to find humans. Because today, not only are we gonna discover how tracking dogs do what they do, but we're gonna test and debunk the five most common bloodhound myths. And for this final showdown in the woods, she has one hour to find me, but what she doesn't know is I've done my research and engineered up every contraption in the book to give me some glimmer of hope against her unfair, superhuman advantages.
But as preparation for that big forest finale, in order to understand the limit of the dog's capabilities, I first extended an invite to CrunchLabs to run through some basic tests starting off with a simple challenge involving just my hat. This, by the way, is Shay, and this is Zinka. Now what makes Shay so cool is she's been working as a volunteer, expert, search-and-rescue handler for over 30 years, which means with all that experience, she and her dogs have pretty much seen everything.
But have they ever seen this? I mean, could you find me amongst all these tastefully distributed human mannequins? Because all I see is a guy with incredible-flowing Jimmy Knorp hair.
Now, as for Zinka, after checking out all her options, she made pretty quick work with the exercise. (Zinka barking) (Mark laughing) Do I smell that bad? It was me all along Shay.
(Shay laughing) So outta the gate, I'd learned two things. First was that even an expertly-trained human hunter- Go get it. Still enjoys the game of fetch like any good girl.
And the second was Zinka's not actually a bloodhound. - This is a German shepherd. - That's what I thought.
For our first of five myths we're debunking regarding scent-trailing dogs, these days, bloodhounds are almost never used. The most common dog breed for search dogs are German Shepherds like Zinka, because research shows they're just as good at discerning smells as a bloodhound, but they're also extremely intelligent. Shay explained that picking up on the scent is like Zinka finding the puzzle pieces, but it takes her intelligence to put the pieces of the puzzle together.
And now that we've cleared that up, it was time to run some real tests. All right, Shay, the hiding test. Can she find me hiding in the lab?
Everyone's dispersed out there. I got a good hiding place too. - [Shay] But I need a scent article.
- What works is a scent article? - Your wallet. - (laughing) My wallet.
How about my watch? - Your watch would work. - Okay.
There you go. - Sure. - So I was off to my killer hiding spot, and after a quick pizza distraction, I threw my first curve ball by using the fireman's piston instead of the stairs to get to the lower level.
Then it was up the other stairs to bury myself under a blanket of cubes in the foam pit. Yeah, bury me. See if she can find me in here.
Then it was Zinka's turn. And you can see here just how briefly she needs to sniff my watch to lock in on her target. Outta the gate, you could see she also falls for the pizza distraction.
- [Shay] Don't eat the pizza. - [Mark] And then walk straight to the spot, where at least to her nose, I had somehow just teleported away. (Zinka barking) (Shay utters command) And while this might have tripped up Zinka, Shay was onto my antics and helped reconnect her to my trail below, which meant from that point, as you might have guessed, my fate was sealed.
Oh no. (Zinka barking) (Shay and Mark laughing) How you. .
. (light music) Well, I'm gonna get you on the next one. Okay, Ryan, are you good at hide and seek?
How good? - This good. - Whoa!
For this next round, I wanted to test something Shay mentioned to me that I found really hard to believe. - If multiple people touch an article, they can scent discriminate and find one person out of all of them. - I need some volunteers.
I just rub this on their arms, right? Basically six of us combined all our scents onto a single paper towel with a brief arm rub. Then only Ryan jumped in with 15 other decoys and went to hide throughout the lab.
And as long as the other five of us started off next to Zinka, apparently she could do the math, isolate just Ryan's scent as the missing one, then identify it among 16 decoy-scent trails that led down the stairs, which is just certifiably bonkers. That's it? - Yep.
Let's go search. - That's this, by the way, is where that puzzle-solving intelligence, I mentioned earlier. .
. I know where he's sitting. She's going right there.
Comes into play. (Zinka barks) Ah! It's borderline witchcraft.
That was nothing short of magic. What the heck is going on? - She's gonna tell you.
(Zinka barking) - Which honestly I took as a challenge. So we doubled the number of arms to rub on that single paper towel to 12, which meant she would now have to isolate the single missing person from the 11 others, then track only that scent amongst all the remaining decoys. That's crazy.
So she's eliminating all of them right now. - Lets go search. - Dude.
No way. And honestly, this one somehow seemed even easier for her. (Mark laughing) No way!
- [Shay] Good girl! - Bonkers! Good work.
Actually bad work. You got found. I lost another bet.
For the final test, I wanted to investigate the potential myth that the reason Zinka can uniquely tell us apart is because she's actually detecting trace amounts of everyone's unique DNA left behind in their skin cells. That hypothesis would also explain why even though my hat, watch and arm all smell totally different, even to my untrained nose, she still knows they all belong to me. The problem was that to test the myth, I need to somehow find two people with exactly identical DNA, but as chance would have it.
. . Welcome to CrunchLabs.
So the plan was to get a scent article from one identical twin but not the other and then see which one Zinka would go for. Go hide! To remove any doubt, we have the wrong twin hide in plain sight exactly along the path to the right twin.
Wow. And there was no question Zinka skipped the twin to secure the win. (Shay laughing) Which meant the DNA-sniffing myth was busted and Zinka is in fact just picking up on complex scent molecules that contain unique chemical compounds for every single person.
And at this point, while I was clearly outmatched, I'd already identified a few potential chinks in Zinka's armor that I could exploit for our final showdown in the forest. But I can only learn so much inside CrunchLabs with only 25 volunteers. So what if I could find several thousand volunteers on a much, much larger playing field?
And this beautiful college campus in Berkeley, California provided me the perfect opportunity. My thought was that having now moved outdoors, the plethora of interesting aromas in every direction might obscure my own scent trail. On top of that, having arrived a little early, I had some opportunities to covertly pass around some of my scent molecules before finally receiving the word it was go time.
There's no possible way you're gonna find me, girl. What do you need from me? - A scent article.
- Like a sock? - A sock would be great. - Sorry, girl.
- Me or her? (Mark laughing) - Both of you. And with that, I made my grand escape with a generous 45-minute head start.
Okay, there are people everywhere. It's like really windy today. The wind's going this way so I kind of wanna go this way.
Keep my scent down wind. There was no time to waste. (camera shutter clicks) There was barely any time to waste.
And so I did what I could to leave my personal molecules behind all around campus. I wasn't exactly sure what it would take to ward off Zinka and Shay, but whatever it was. .
. Parkour! I just knew it had to look cool.
She'll never figure this out. This is terrifying. I feel like I'm being hunted.
I guess because that's exactly what's happening. There's a bunch of people over here. I was going for a big loop once I saw the number of people gathered in the quad when an opportunity presented itself for me just to express some heartfelt appreciation.
- Bro! - To some good folks who subscribe to my channel. There you go.
Hug it out, you know! - Thank you. - And to be clear, this was kind of my checkmate move.
A dog might be chasing you in a second. Be cool. Hey, give me five, I'm being chased by a bloodhound.
Can I give you five? I'm being hunted by a bloodhound. - Really?
- Go that way. There is no possible way this dog is gonna find me. The worst part about all this is I have no sock on my right shoe.
I'm actually parked up here in a garage. If this dog finds me, welcome our canine overlords. I'd made it to my final hiding spot with a few minutes to spare.
That's my car. This is basically a massive Ziploc bag. All right, I'm laying low here in my car.
I feel the need to whisper, even though there'd be no way she could hear me. But not long after, the timer was up. - [Shay] Let's go search.
- And Zinka quickly got to work. And right outta the gate, I tripped her up as she stopped at my bench for a good long while. But eventually she realized I was more than just a bench and she carried on her search.
I don't really have any inclination as to whether or not she's found my scent or not. And while she wasn't that interested in my selfie friends, the same can't be said for the campus squirrel population. (bell dings) - Squirrel!
Nope. Leave it. - I'm gonna pull a dirty trick.
I'm moving spots. Is this cheating? Absolutely.
And unfortunately for me, she just totally short circuited my clever loop maneuver. But then she seemed to get caught up with all the scents in the trees and bushes near the parking garage. And while stopping to smell the plants didn't save me.
. . This is terrifying.
When she bee-lined for my original parking spot, I thought I might actually be in the clear after all, but not even my dirty tricks could overcome her lock on my dirty socks. No. .
. . .
. way. What the crap?
(Mark laughing) No way! How is that even remotely possible? Does it smell that bad?
So while I did have some very minor victories amongst all our testing, I knew I needed to consult someone who had been here before. Someone who was a personal hero of mine, and the true OG when it comes to busting myths. Mr Adam Savage.
The cave! - You have been here, but it's been a few years. - I've been here, but there's nothing like actually being here.
The organized chaos of it all. And so after briefly soaking in his incredible Cave of Wonders, we got right down to business. I'm here, Adam, because I need help.
Bloodhounds, am I right? - That was one of my favorite sets of episodes we ever did was the bloodhound. - In addition to talking about everything he's learned about scent-trailing dogs over the years, we talked about the best mental model for even understanding how Zinka's brain works.
Because one way to think about it, is everywhere you go, you leave behind a trail of scent molecules. In fact, it doesn't matter if you're walking or even standing still, you shed 40,000 dead skin cells into the air every minute. So to a dog's nose, the trail of all those skin-cell scent molecules might look like this with a unique color for every person.
But instead of six unique colors like you see here, she would need to have at least 8 billion unique colors since she can ostensibly tell everyone on the planet apart, down to identical twins. Additionally, if she knew your scent and then you used a different soap for that day and tried out a new cologne, she would still know you as your exact same color. And that might seem like crazy magic and it sort of is, but to give you some sense of how a brain might work that out, let me ask you a question.
Do you recognize this person? How about this person or this one? We kind of think of it as no big deal, but your brain also just identified Steph Curry out of 8 billion people on this planet, which is pretty cool because our brains don't have that same unique identifying capability for, like say, every tree or rock you meet.
And furthermore, just how Zinka's nose can pinpoint me if I'm wearing a different cologne, you can still tell us Steph Curry, even if he's wearing a hat or sunglasses or heck, even both. To continue the analogy further, the way her brain catalogs my unique scent from a sock is the equivalent of the way our brain catalogs a unique face from a missing person flyer. And to further defend the capabilities of our own species, for myth number three, it's actually not true that across the board we're 1,000 times worse than a dog at identifying smells, cuz in a few areas, we're actually better.
For example, you can practically smell this footage here, right? That's because we can identify the chemicals that enter the air after freshly fallen rain at one part per 10 billion. That's 100 times more sensitive than a shark's nose when identifying blood.
We know in the desert, camels rely on its scent to locate sources of oasis water. And so it stands to reason, it provided an evolutionary advantage to our ancient ancestors as well. Now, as for Adam, I'll return to some additional advice he gave me in just a minute, but for now, after of course having him sign my original MythBusters blueprint, I showed myself out the door.
I might take a few things on my way out. - No worries, man. Whenever you want.
- You heard him. (laughing) Here we go. Ah!
So after my discussion with Adam and poring over all the footage from all our tests from every angle, I was feeling a renewed confidence. I'd pinpointed a few of Zinka's weaknesses, and if you were paying attention, you might have picked up on a few of them as well, which meant all I had to do now was exploit those weaknesses with a 12-second build montage. (intriguing music) And so after jamming all my tricks into a single backpack, it was time to head out to meet up with Shay and Zinka for the final showdown.
(door slams) But before we get to that, I just wanna know, are you already bored this summer? (explosion blasts) (dramatic music) 'Cause if so, oh boy, have I got the answer for you? And it's called Camp CrunchLabs.
It's kind of a 12-week virtual summer camp featuring weekly videos with mega experiments that I do, and then weekly challenges that you do. And the best weekly challenge submission of the whole summer gets a platinum ticket to come out right here to be in the 12th and final summer camp video with me. (air blasts) (Mark laughs) On top of that, usually the CrunchLabs build boxes where we build a really fun toy together where I teach you all the juicy physics of how they work comes every month.
But to coincide with the Camp CrunchLabs' weekly videos and challenges, you have the option to get them every week. - Yes! Look!
- So if you want a 12-week summer camp where you can learn to think like an engineer with 0% chance of sunburn or mystery-meat casserole, head to campcrunchlabs. com where you can reserve one of the limited spots and I'll see you at summer camp. Shoo.
All right, Shay, I got my bag of tricks. May the best human or canine win. Here we go.
It's game on. And thus began the final showdown. My plan was to lay seven traps for Zinka and Shay along the route that I had secretly predetermined.
And the rules were, once I'd set all my traps and arrived at my final position, Zinka would begin. And if she couldn't track me down in less than an hour, I'd be declared the winner. And shortly after regretting not having checked the weather forecast.
. . Picked a bad day to wear a down jacket.
I was ready to set my first of seven traps. From Berkeley, I knew my socks really stink, so I would tie one of my extra smelly soccer socks to a drone and set it on a timer delay and then I would sneak off down a side path. And of course, I knew my body would leave behind way more scent molecules than my sock, but the time delay would mean that when the drone flew the pre-programmed flight path, eventually veering off the road and releasing the sock from the server motor in the bushes, that scent would be much more recent and fresh for Zinka to hopefully follow.
All right, this one might be my personal favorite. And now that I was off the main road and into the woods, I found the perfect spot for my second trap. Smells gross.
I knew for reviewing the Berkeley footage that Zinka was extremely interested in squirrels. Taxidermied squirrel. Not fat, guys, for the record.
Shay later confirmed this and let it slip it was a combination of their quick movement and their smell that she just found irresistible. So between train-track squirrel and taxidermy squirrel, our bases were covered. Now obviously, this trap wasn't going to trick Shay.
The idea here, was given Zinka's weakness for squirrels and their one-hour time limit, every precious minute I got them to waste would increase my chances. After that, I continued up the trail for a few hundred yards until I came to another convenient fork in the path, perfect for my third of seven traps. I wanted to lay another deceptive trail of my scent molecules going the wrong way in case the drone sock didn't work out.
Only this time, to really cover my bases, I was going for a three-pronged approach. This land-based vehicle, also known as the Mark Rover would've one of my sock in a compartment with a fan that would blow out my scent and then another sock in a liquid container. .
. Make some nice sock soup. That would spray out my scent in case the scent molecules would bond well with the water.
And then for the third, since I was outta socks. . .
(sighs) The part I'm not looking forward to. I'd have to go straight to the source. Using a cheese grater, I harvested some actual pieces of meat combined with some sawdust, so when the time came, it would slowly leave behind and overwhelming trail of me along with the other two methods as the rover misleadingly roved along.
And by the way, these weren't just Hail-Mary ideas cuz we ran some tests on Zinka showing she could easily isolate my scent using all three of these approaches. You got earth, wind, and water. The trifecta.
What I don't have is a change of socks. Dang it. So with everything set and the rover timer counting down, I socklessly set out to set up trap number four.
And this next one is a doozy. This is basically a massive plane and propeller just without the plane. (engine turns over) The thinking here was I really confused Zinka when I used the fireman's piston cuz my scent trail just seemed to stop.
Additionally, after reviewing the Berkeley footage, I noticed the reason she got caught up on the bushes outside the parking garage was thanks to the strong crosswind blowing my scent off the sidewalk. So what if I took that to 11 with some 95-mile-an-hour, hurricane-force winds? Ah!
(hard rock music) Yeah! Yes! I lost all my clothes, but I also lost a lot of skin cells hopefully.
Good luck with that, Shay. And since Zinka would definitely be wanting to follow my scent off the road in the direction of the wind, I picked a random spot to sneak off in the other direction on a trail leading straight to the heart of the redwood forest. And there was a stream running alongside the trail, so I took the opportunity to test the idea that dogs can't track you if you're stepping in water that's sweeping the scent away.
Oh. Which was super awesome when you're already hiking without socks. From there it was all about agility and stamina to cover a lot of ground through the redwood forest.
With five of my traps set and only two to go, I was feeling confident nothing was gonna break my focus on the task at ha- Ooh. Oh, wow! (laughing) Yeah!
All right. Back to the hunt. (gentle music) I can't pretend I'm in shape anymore.
Which was good timing because having exited the forest, it was time for my sixth and possibly strongest trap of the all. I've got some big plans for this meadow right here. I'm gonna put a bunch of my scent in this clearing.
The idea is to overwhelm this area with my smell. And believe me when I say, at this point, I don't smell that great. The genesis for this idea came from seeing how Zinka got tripped up at the bench where I spent a long time waiting.
Because there was just a ton of my scent molecules lingering around versus the relatively small amount of scent molecules for my single exit trail. And for part two to further obscure my path, I had a special surprise. The bunny suit.
I spent about five months wearing one of these every day at NASA as I tested and integrated my hardware on the Mars rover. As you can probably guess by now, the purpose of those bunny suits is to keep in those 40,000 skin cells per minute that we shed, so we don't send the rover headed to Mars looking for life contaminating it with life of our own. And so with my bunny suit on, I would practically become invisible to Zinka's nose for my escape.
Let's go. But to further tip the scales, I held my breath as I ran away. And if by some miracle, Shay and Zinka made it this far, I had two final tricks up my sleeve.
I knew Zinka was incredibly motivated by food because she would go for any morsel that was left out. Plus that's how Shay rewarded her when she successfully found her target. In one of our conversations, Shay let it slip that her favorite foods were chicken and cheese.
And wouldn't you know it, but I just stumbled upon a bunch of chicken and cheese. That's gonna take her the wrong way down the path. Oh yeah, that's a good meal.
(laughing) And then if somehow she tracks me all the way up here, I'm walking right in front of these many fans so all my scent goes out into the valley. And this is where I will sit to monitor all the proceedings. All right, team, I am in position.
If she's ready to go, we can start the timer. - Good to go. - Okay.
Clock starts. . .
. . .
now. (clock ticking) She has an hour to get through all my traps. I just have to sit here and wait.
Not long before they started, my drone had taken off right on schedule and dropped the payload on an unsuspecting bush. And exactly as I'd hoped, Zinka got to the fork in the road and you could see her trying to work things out as she starts heading right towards the sock bush. But then you can almost see the moment when she realized that it wouldn't be a typical search.
- [Team Member] All right, mark the drone sock didn't work. She went right by. - Oh no.
(chuckles) There's no doubt at this point I was dealing with the true professional, but I was confident that with the right distraction, I could throw off her game and waste a considerable amount of their valuable time. - [Team Member] Well, she loves the squirrel. (playful music) - Of course she does.
What's not the love? (music continues) Did it throw her off? - It did.
- Stop chasing it. Let's go. - [Team Member] She's gotten back on track.
- [Mark] This actually brings us to our fourth of five myths. These dogs aren't working alone. - It's not just a thing that the bloodhound can do.
It is a partnership between the bloodhound and the handler. You don't get one doing their job at the highest level without the other. - And in hindsight, I guess this seems obvious, but it wasn't something that had occurred to me.
Shay's there to help Zinka stay focused, and if she's stumped, she can help think of different ideas to help her find the trail again. Just like when I jumped down to the first level and Zinka was sure I'd teleported until Shay Deuced what probably happened. Hopefully they lost valuable time there.
That counts for something. But Shay wouldn't be much help at the next fork in the path where I was pleased to hear the Mark Rover had initiated its time-delayed journey exactly as planned. Dutifully wafting, spraying and littering a fresh trail of me as it roved all the way down the path.
This was a massive level up from the drone sock, which meant they were going to get so tripped up, it almost felt unf- - Nope, car didn't work. - What do you mean it didn't work? Did she at least follow it a little?
- [Team Member] Just a little. But really where you were walking. She went back on track.
- Not cool, Zinka. Not cool. No way she gets my mega fan.
I'm calling that right now. I lost my jacket and one of my 37 hats to this monster so I really wanted this to work. And this time, I was not disappointed.
- [Team Member] It looks like Mega-Fan might be working. - We got a hit. - [Team Member] She is moving in the same direction as that wind.
- She really seemed to be confused about what her nose was telling her and sensing this and seeing the massive fan, Shay put two and two together and called her back up to look elsewhere. But then when Zinka hit on my actual escape route, Shay assumed it was another bad signal and called her off again. And this is where you can really see the mutual trust they have for each other.
Because eventually Zinka circled back as if to say, "Nah, I know it. This path is totally right. " At which point Shay understood and they headed down into the redwood forest.
- [Team Member] Oh, she's back on track. - What? - She didn't take the bait.
- Dang it. It sounds like a that was my closest one so far. With the ravine and the water, this could be my.
. . This could be good.
- [Team Member] She seems to really love the water. She's frolicking along. - Frolicking?
(dramatic music) - [Team Member] This seems to be the fastest. - [Mark] What do you mean the fastest? - [Team Member] She's moving along the pot the fastest.
Seems like the smell is right on the water. - Oh, good. I'm glad I have 12 blisters and like really nasty, smelly feet for nothing, then.
Shay would later confirm this as our final myth to bust, but scent molecules are actually hydrophilic, meaning they stick strongly to the water and the edges of the stream, making it in fact easier to track than just a normal path on land. And since Zinka was feeling refreshed from all that stream frolicking, she had no problem keeping up the pace for this endurance portion of the hunt, which was good cuz she was about to hit an olfactory brick wall. How close is she to the clearing?
- [Team Member] She's almost here. - Okay, I think this is where it's game over. I'd spent about 20 minutes just trudging around this clearing.
- [Shay] Now you're done. We're on a roll. - Leaving an overwhelming number of my scent molecules behind.
. . If you get too discouraged cuz she can't find me, let me know and I'll come down the hill.
Before putting on my NASA suit for my quick escape, which meant at least from the perspective of her nose radar, I had effectively disappeared. - [Team Member] Wow. No hesitation.
She went right through. (disappointing music) - What? Really?
Zinka, you're killing me! I think my minutes are numbered. Ah!
She is on her way up this hill. She's got about 15 minutes left. But if the chicken of cheese could just distract her enough, I may have a glimmer of hope here.
- Nope. Get to work. No.
Hey, get to work. - [Team Member] Oh, it totally worked. - Yes.
- Zinky. (Shay smooches) Come on, get to work. - [Team Member] At the second bowl now.
- [Shay] I know those are good. - [Team Member] Oh, she's got a whole bunch of chicken and cheese. - She's working her way up the bowls of the chicken and cheese.
- Munching away. - Come on, leave it. - Clock's ticking, Shay.
If I'd only quadrupled my chicken and cheese order, I might have stood a chance, but as it was, she immediately backtracked down the fork and headed straight for me. It's nerve-racking. But then, at what only could be described as an 11th-hour salvation, the final three fans seemed to trip her up and she second guessed herself heading back down the path.
- [Team Member] It's interesting, she came back down towards the bowls. - [Shay] Come here, Zink, come on. Oh, more.
- Okay, scratch that. Knowing there was time to spare, she apparently was just flexing on me and double checking the bowls were in fact completely empty. So with a full belly and the proud gait of a winner, she led Shay around the bushes to my final hiding spot.
No! (Shay laughing) - Good girl! - No!
Bad girl! That is like indistinguishable from magic. And as I sulked in my loss with all of us overlooking the valley, I asked Shay why she's been volunteering around 20 hours a week for over 30 years working with search-and-rescue dogs.
- Hopefully bring a good conclusion to a very stressful time for a family. - And so for the hopes of many more future families to come, I suppose my loss really seems like the best possible outcome. The best mammal won.
You were a formidable opponent. Oh. (Shay laughing) Opa!
In my ongoing quest to be the favorite uncle, I built a fire-extinguisher-powered hovercraft. (Mark screaming) And then I challenged my nephews to make it across my human-sized glue trap. (all laughing) Now these are both part of Camp CrunchLabs, which is a virtual summer camp to help you fight both boredom and summer brain drain.
(explosion blasts) (kids shouting) But it's also an example of the type of juicy content that's just automatically included when you have a CrunchLabs subscription. That means, on top of just getting the boxes delivered right through your door every month where we build a really fun toy together, as I teach you all the mind-blowing physics of how they work, you also get exclusive access to stuff like behind-the-scenes content for my main channel videos. On top of that, CrunchLabs is a real place.
So every month, we randomly select one box to slip in a platinum ticket, and if it happens to be your box. . .
- [Father] Oh my God! You won, buddy. - Oh my God!
(child cheering) - Then you're coming out right here to design with me and my team for the day. So if you want to unlock the superpower of learning how to create and build whatever you can dream up, go to CrunchLabs. com or use the link in the video description to learn more.
Thanks for watching. Yes. Nailed it.
