We often hear that dogs help lower our blood pressure, decrease our allergy risk, and even alert us to disease. But is there science behind those claims? In this episode of Tiny Matters, Sam and Deboki unpack some dog domestication history and fascinating research with Jen Golbeck and Stacey Colino, authors of the new book, The Purest Bond: Understanding the Human-Canine Connection.
Transcript of this Episode
Sam Jones: [whining audio from Yuca] That is my dog Yuca, staring at me as I eat dinner, begging for food scraps.
It’s kind of funny to think that this is reminiscent of how the human-canine relationship began. Granted, it was not at a kitchen table and definitely not with an animal that looked anything like Yuca who is a Boston terrier-Frenchie mix. It all got started with wolves.
Deboki Chakravarti: Although it’s still debated, the most popular theory behind the domestication of wolves is referred to as the commensal scavenger hypothesis, which is that wolves more-or-less domesticated themselves by wandering around ancient hunter-gatherer settlements in search of food scraps. And over thousands of years, increasingly docile, friendly behaviors were selected for, giving rise to a genetically and physically distinct canine: the dog.
A genetic study a couple of years back proposed that dogs were already living among humans over 23,000 years ago, but the earliest remains of people and dogs together date back to the Paleolithic era, just over 14,000 years ago.
In 1914, workers uncovered a grave in what’s now a suburb of Bonn, Germany. In it they found the remains of a dog, a man, and woman, along with several objects made from antler, bone, and teeth.
Sam: And when the findings were reevaluated over a century later, researchers not only discovered the remains of an additional dog — they were able to determine that one of the dogs was still a puppy, and lesions in its mouth and changes in tooth enamel suggested that it died of distemper, a highly contagious virus, and suffered through two or three periods of serious illness before dying. And to survive it almost certainly needed help from humans.
So we have been taking care of dogs for a while. But today’s episode is about how they also take care of us.
Welcome to Tiny Matters. I’m Sam Jones and I’m joined by my co-host Deboki Chakravarti. I have two dogs — Yuca, who you heard earlier, and Ziki …
Deboki: … And although right now I have a cute cat named Bastian who might disown me if I got a dog, I’d love for there to be a dog in my future because I just really like them! They seem like a lot of work but also a lot of fun.
You’ve probably heard somewhere that dogs are good for us, not just because they get us to go outdoors and have more fun, but because they reduce our stress, lower our blood pressure, alert us to danger and disease, and make us less likely to develop allergies… but is there really science backing up those statements? That is where our guests come in.
Sam: In today’s episode, Deboki and I spoke with Jen Goldbeck and Stacey Colino, the authors of the new book The Purest Bond: Understanding the Human–Canine Connection, a feel-good exploration of the profound bond between humans and dogs.
Deboki: Jen Golbeck is a professor at the University of Maryland and a computer scientist by training. She’s also the creator of TheGoldenRatio4 which is a very popular social media account featuring Jen’s rescue golden retrievers. Stacey Colino is an award winning health and science writer and lifelong dog lover. Right now she and her family have a rescue named Sadie.
In The Purest Bond they cover a huge range of topics including understanding your dog’s behaviors and the ins and outs of dog ownership — from getting a puppy to the later years caring for an aging dog. Today we're going to dig into some of the fascinating science research in the book so that if someone says, “But do dogs actually reduce our stress?” you can say “Yes! And here’s how we know.” But first, we wanted to know what prompted Jen and Stacey to take on such a big project.
Sam with Jen and Stacey: What about dogs draws you to them so much that you would write a whole book? There's probably a massive list, but what would you say some of your main motivations were for writing The Purest Bond?
Jen Golbeck: I started talking to my book agent about this really early in COVID lockdown when a lot of people were adopting dogs and bringing them home. And we were talking about how dogs have all these great effects. And that's something I've always been interested in, even though it isn't my area of study. When these studies would come out that were like, “oh, if you have a dog, if you have a heart attack, you actually live much longer than people who don't have dogs, even if you control for walking,” I was always totally fascinated by those studies. And so the timing seemed like this might be a good time to write a joyful book because there are not that many of those these days.
I wrote a couple sample chapters and gave them to my agent, and they were like, “Hey, this is great. Have you thought about working with a professional writer to help you?”
And I was like, oh, my feelings are a little bit hurt, but also that's a great idea and will probably make things much better. That's how I met Stacy who came on and we ended up being 50-50 partners writing the book.
Stacey Colino: Well, it was funny, I don't even know if Jen knows this story, but my agent came to me and said, well, this colleague here has a project that we both think you would be great for, but you're busy writing this other book, so your plate is probably full. And I've been on the fence about whether to even tell you about it. And I said, well, tell me what is it. And she mentioned it and I was like, are you kidding me? This is totally in my wheelhouse and this is right up my alley. I am a total dog lover… And it was really great timing for me because a month earlier, my beloved dog had Inky had died. It was very, very sudden and he was 13 and a half.. And I was just so devastated by this, the whole family was. We made it one month without a dog. We really don't know how to live without a dog. And then we discovered Sadie. She had been put up for adoption. She was one of those dogs who was a little bit older.
Everybody wanted a puppy at this point in the pandemic, and she was five at the time. And we went to this horse farm in Virginia and met her and a whole bunch of other rescue dogs, and she jumped in my car and didn't want to get out. She chose us. And so it seemed like this was a great opportunity to celebrate this bond that's so magical and so deep and that people were experiencing on a deeper level during the pandemic because they were spending more time with their dogs, but also new people were discovering for the first time as they adopted dogs or bought them for the first time.
Deboki: The first thing Sam and I chatted with Jen and Stacey about was the microbiome. If you’re a long time listener, you may remember we covered the microbiome a while back, in episode 23.
Stacey Colino: We all carry microbes on us and inside us. Dogs have microbiomes too, and anybody you share a home with has microbes in common with you because you share some of the same stuff. You touch each other, you hug each other and so on. And with dogs, they have bacteria and other microbes on their fur and in their saliva. That enters our bodies and vice versa, microbes from our skin go onto them. And so these studies have found that when humans live with dogs and they have a close relationship, they have a lot of microbes in common. And so it changes the composition and the diversity of the bacteria and other microbes inside our gut microbiome, but also our skin microbiome. People don’t realize we have multiple microbiomes.
Deboki: Your microbiome is made up of a huge number of species of microbes, both ones that are good and bad. A study in December of last year done with 54 dog owners over the age of 65 showed that dog ownership doesn’t necessarily increase the diversity of microbes in a person’s gut but it does seem to increase the number of those beneficial microorganisms and suppress the number of harmful bacteria.
Growing up with a dog has also been implicated in allergies.
Stacey Colino: Some studies have found that when kids are exposed to dogs from a young age, it actually decreases their risk of developing allergies not only to dogs, but to other things as they grow up, which is pretty amazing.
Sam: In March of this year, in an analysis of over 65,000 infants in Japan, researchers found that children exposed to pet cats or indoor dogs while still in the womb or during early infancy tended to have fewer food allergies compared to other children. Specifically, kids exposed to indoor dogs were significantly less likely to experience egg, milk, and nut allergies and kids exposed to cats were significantly less likely to have egg, wheat, and soybean allergies. I also want to add that they found children exposed to hamsters, which to be fair was less than 1% of the total group but still thousands of kids, had significantly greater incidence of nut allergies.
Deboki: That’s so weird.
Sam: I know, I just had to mention it. OK, so the next thing we wanted to talk with Jen and Stacey about was stress. How do we know that dogs can reduce our stress and blood pressure?
Jen Golbeck: The research on the impact of dogs on blood pressure, especially in stressful situations, is so interesting. There's a ton of different studies on this where sometimes they'll have a group just sitting in a room by themselves. Sometimes we're looking at groups who are going into therapy for PTSD or even electroshock therapy for major depression that's resistant to treatment. They will have people do math tests or little math problems in their head, which is actually a really good way to get people to feel stress or put them in a physically stressful situation. So your blood pressure might go up, your heart rate, your breathing. All these studies then introduce things to try to modulate that.
Deboki: So maybe it’s your partner being present, or a stranger, or … a dog.
Jen Golbeck: And consistently what these results show in all these studies is that if you pet a dog, your levels of stress are going to go down. And often that your performance, if you're looking at something like a math test, will go up. But you just feel better. And we can describe that as a sense of well-being that we feel better, but also you'll see your blood pressure come down, your heart rate comes down. If we get to measuring hormones that reveal stress, those levels also go down and it's remarkably fast. So it can be less than 10 minutes of petting a dog — not even your own dog, just any dog — and you're likely to feel better. And it has really profound implications. I mean, obviously, it's great if you can just come home and lay down with your dog and pet them and feel better. But if you're looking at situations where you really need people to relax, if they're testifying in court about something traumatic, if they're trying to perform on a test, if they're in therapy and you need them to kind of relax so they can connect with what they're doing, the presence of a dog there actually can be really helpful.
Deboki with Jen and Stacey: Is it specifically the action of petting a dog? Is it enough for the dog to be in the room with you, or is it also something about the petting motion and the interaction with the dog that's soothing for people?
Jen Golbeck: That's a great question. Literally just having a dog in the room can help. You don't even need to interact with them.
Stacey Colino: I just wanted to add on to what you're both getting at here, which is that there are studies, most of which came from Japan, that have looked at the effects of looking into your dog's eyes for a certain amount of time and how that affects your hormones. And they found that when people looked into their dog's eyes for five to 10 minutes, both creatures experienced a surge of oxytocin, which is a feel-good hormone. It's often called the bonding hormone, the love hormone, the cuddle hormone, and they're not touching, they're just looking into each other's eyes. That's how profound this connection is.
Deboki with Jen and Stacey: That's super interesting because that was the other thing I was wondering about, Jen, while you were explaining the research, is, how much of it is mutual? I would love the idea that when I'm with the dog, I'm getting all of these benefits. Is the dog getting any benefit from me? Am I doing something for the dog?
Jen Golbeck: This is one of my favorite kind of meta results I think that came out of doing this book. We know we can talk about how we feel when we interact with the dog, but I think a question that comes up, especially when you're a dog person talking to non-dog people is like, does your dog actually love you back? And I'm going to say of course my dog loves me back, but do they really, or are we just making that up? And I think the science is quite clear that they do. But my favorite result from the book is based in fMRIs.
Sam: Functional magnetic resonance imaging or fMRI is a non-invasive imaging technology that measures brain activity by detecting changes in blood flow to different regions throughout the brain.
Jen Golbeck: In psychology, there's this concept called attachment bonds, which is the bonds often form between mothers and infants. They're really important. They affect all of our relationships for our whole life. And we know that you can put babies in an fMRI, so you can see the parts of the brain that are lighting up, and they can hear their mother's voice or see a picture of their mom in certain parts of their brain light up. And those are the parts that are connected to attachment bonds. So these are the closest, most loving relationships that you have. They're places that you go to feel safe to kind of come home to. And so we know the part of the brain that's connected to attachment bonds, and they've done similar studies in dogs where they have trained these dogs to lay perfectly still in an fMRI, and then they will let them hear the voice of their owner or smell their owner.
And the same part of the dog's brain lights up in a baby when they see their mom. And so what that says is that our dogs on a biological level seem to be showing evidence that they also form those bonds back with us. Which of course, like anybody who has a dog knows that that's true, but it's good to do the science for it. And I think these all kind of come together to be like, yeah, the dog is getting something out of this relationship. And it's not just that we take care of them and we feed them, but they're emotionally connected to us in these really profound deep ways like we see between the closest human relationships.
Sam: We also really wanted to ask Jen and Stacey about medical alert dogs. You might remember that in episode 28 we did a deep dive on detection dogs and how the dog olfactory system — their smell center — works. But we mainly focused on dogs who alert us to the presence of explosives.
Medical alert dogs are focused on alerting their owner to whatever it is their owner needs to know about. Maybe the owner has a severe airborne allergy to nuts. Their medical alert dog would be trained to detect trace levels of odor from, say, peanuts. Or if a person is diabetic they might have an alert dog trained to pick up on odor molecules specific to low levels of blood sugar.
These dogs are so keenly aware of what we smell like that they can pick up on chemical changes in our sweat or breath or even urine.
Jen Golbeck: An interesting study that was done in Milan at a research center there, they actually took bomb detection german shepherds and trained them to try to recognize prostate cancer in urine samples. And so they had all these jars and some were cancerous and some weren't. There were two of these German shepherds. One of them was right a hundred percent of the time, and the other was right 98.6% of the time, out of 362 samples. So it's not like, oh, there were 10 samples and they kind of got lucky, right? There were hundreds and hundreds of samples and these dogs were basically perfect at detecting cancer.
Sam: And even without extensive training, many dogs will still alert to a problem with their owner. I loved a story that Jen told about a dog named Chomp, who was so tuned in to changes in his owner’s breathing that it saved the owner’s life.
Jen Golbeck: When we were writing the book, I was having a dock put in at my house. We live down near Key West, and the guy who's putting the dock in was a big dog lover, and I'd always bring my dogs out to say hi to him when he'd check in on it. And I told him that we were writing this chapter and he told me this story about Chomp, that's now in the book, where he was basically just about to have a heart attack and woke up to his dog doing what he called doggy CPR, bouncing on his chest, waking him up in the middle of the night.
The dog would not leave him alone, and he took himself to the doctor in the morning and they actually airlifted him out of Key West up to Miami to have surgery to fix this blockage in a major artery that would've killed him if they hadn't fixed it. And he's like, “the only reason I did that was because Chomp knew that something was wrong.” And it's this beautiful story. He's here a decade later, Chomp is no longer with us, but John, the guy in the book is. And it shows that dogs really know intimately what's going on with us.
Deboki with Jen and Stacey: So I guess as the resident non dog owner, if I was to get a dog or anyone else, if they were about to get a dog for the first time, is there a piece of advice you would give about the experience?
Jen Golbeck: I mean, it's great, but it can be chaotic. And one thing that we open up the book with is talking about when you get a new dog, whether it's a puppy or a rescue dog, you really want to set the conditions for you to form this bond effectively. You want them to feel like you are a person who is safe, who's trustworthy, that they don't have to worry about. And that means paying really close attention to what they need and what they don't want. Do they want hugs? Do they want you to kiss them on the face? I mean, my dog Guacamole, if I try to kiss him on the face, he turns his head away from me very dramatically. He just doesn't like face kisses, whereas my other dogs want me all up in there and that's great. Do they want to play? Do they want to kind of hide and just settle back in?
Those first couple weeks they will be a different kind of dog than they potentially will turn out to be because it's such a big adjustment. And I think that's a point where if you can show that you're going to respect what they need, give them the space or the attention, it forms the foundation for that really trusting bond in your relationship going forward.
Stacey Colino: I would echo everything that Jen said there. I think time and space are absolutely key. When we got Sadie, our previous dog was a real cuddler, and I told my kids, don't hug the new dog. Don't hug the new dog — blanket rule. Got to give her space, let her warm up to us. She is the cuddliest dog I've ever seen. So they laugh about that now because now she initiates the hugs. In addition, I think it's super important, and this is just kind of a learning process as you go to learn to read your dog's body language because dogs signal what they need and what they want in different ways. Sometimes they're quirky about it. And so you really have to just stay highly attuned to those messages and learn to read your dog's body language.
Sam with Jen and Stacey: These are great bits of advice. I definitely wish I had read this book before getting my first dog four years ago. The first dog we got, Yuca, she is a challenge. She is very stubborn, very intense. And there were certain behaviors that I was like, whoa, I was not ready for this. But I adore her and she's actually one of the most sensitive sweet dogs and so perceptive. If I am unhappy or something's going on, she'll hop into my lap and face me and put her paw on me and just try to maintain eye contact. It's really …
Stacey Colino: That's darling.
Sam with Jen and Stacey: So I've developed an appreciation, but man, the first few months with her were rough. I'm sure any of our listeners who pick up your book and are going to be new dog owners will be very appreciative of your advice.
Sam: Tiny show and tell time. Deboki, if I'm not wrong, you have something that is dog themed. So I feel like you should go first.
Deboki: I do have something that's dog themed and it's very related to this episode overall. It just so happened this week that I was working on something for a different project, and I had read this article and then when I realized we were recording this, I was like, this is perfect. This all ties together. And so basically this is for anyone who wants to take all of this conversation about our relationships with dogs and then take it in the bleakest direction possible. Well, not the bleakest. The bleakest is a world without dogs. So maybe the second bleakest, which is a world without humans, where we then wonder what would happen to the dogs. So this is an article that was published actually a few years ago on Aeon called “The Post-Human Dog,” and it's written by Jessica Pierce. And so basically what Pierce is working through in this article is that question of what would happen to the dogs if we just all suddenly vanished from the Earth?
And I think we might jump to this idea that somehow dogs are just going to devolve back into wolves, but that's not really how evolution works. It's not evolution's going to look back and be like, hey, what did you used to be before humans? It's really more like how are the conditions around dogs going to change and how is that going to impact who they are now and how they're going to respond to that change going forward. And so what this article is really more about is thinking about how the dogs are going to be affected by our absence, given the way that our presence is such a factor in their survival. Even dogs that aren't pets still rely on us. They use our food waste for survival, and there's just a lot of ways in which their lives are intertwined with ours. So this is a longer article and so I don't want to give away all of its arguments or anything, but I do think it's a super interesting read for anyone who likes thinking through these ideas and kind of just wants to see where that thought experiment goes.
Sam: Yeah. I'm so curious. Is there one example that you can tease for us?
Deboki: So this isn't necessarily a specific example of what the dogs will become, but it was just something I didn't think about, but it's sort of related to that idea of becoming a wolf again. Basically what Pierce is saying is that at an individual level, they're going to first go through sterilization where because we're not here, a lot of the dogs that are not feral are going to become feral at some point. And so what's really interesting to think about then is how are they going to fit in ecologically and also how is this going to affect their reproduction and all of those strategies Again, even though we don't know exactly where they're going to end up, there's all of these small little details that we have such a hand in their lives. They're not going to be bred anymore. What does that look like for dogs?
Sam: That is such an interesting thought experiment. If I didn't exist, I don't think my dogs would last three days. They would just be like, this stinks. We don't know how to do anything.
Deboki: Yeah, I always wonder what my cat would do without me. And I'm not sure. I always think he's just terrified of everything, but I also feel like I think he's scrappy. I think he's got a little bit of survivor in him, so you never know. Your dogs could surprise you.
Sam: Yeah, I don't know. I think my dog, Ziki, is much scrappier. Even though she's the most lovey thing. She is my protector. She's so small, but she's so intense when she thinks there's any sort of danger. And so I feel like she'd be far more aware of the surroundings and Yuca is very happy go lucky and never concerned really about anything. And so I think that would actually work against her. I dunno.
Deboki: I'm just imagining them trolling the post human apocalypse, they're partnered up and it's just Ziki be like, you can stop. You got to come back over here.
Sam: Totally. In an apocalyptic situation, she would absolutely be in charge.
Alright, so I'm coming to you today with a story about Caecilians, which are not people from Sicily. It's very confusing and I believe this is the correct pronunciation. It's spelled C-A-E-C-I-L-I-A-N-S. So these are legless, worm snake looking amphibians. So when they're born, the babies, they'll actually use their hook shaped teeth to scrape off their mom's skin and eat it. So these flakes are apparently very fatty and nutrient rich. Why am I telling you this? Because we briefly talked about the microbiome in this episode and there was a study that was published a few months back that showed that this skin feeding actually allows the mother caecilians to pass on their microbiomes to their offspring, possibly really helping with the development of their offspring's immune systems. So the way that these scientists actually came to this conclusion, you're like, wait, I'm sorry, a legless worm, snake, amphibians, microbiome, even.
What is that about? They actually analyzed 1.5 million sequences of microbial DNA from the skin and guts of six male adult caecilians, nine female adult caecilians and 14 young that actually came from three of the females as well as microbial DNA from the environment, right? Because that's really important. Are you just picking up stuff that's around them or is this actually something that's specific to their bodies? And so what they found interestingly was that not much of that bacteria that was actually found in the offspring match what was recovered from leaves, water, soil that were in the environment, but in a bunch of the offspring as much as 20% of their microbiome matched the mom's skin or gut microbiome. That doesn't sound like a ton, but it's actually a pretty significant overlap and it's kind of wild to think that it probably is there from just them using their hook shaped teeth to scrape their mom's skin off and eat it. I'm so glad humans don't do that. That sounds traumatic.
Deboki: This is such a terrifying creature. We're recording this before Halloween and it feels very appropriate. If you want to look up something terrifying, I feel like it’s one of those creatures that is very nightmare inducing, but this is also fascinating and weirdly heartwarming. I know it's the weirdest combination of maternal love and hook shaped teeth.
Sam: It's the perfect combination.
Deboki: Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Society. This week’s script was written by Sam, who is also our executive producer, and was edited by me and by Michael David. It was fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design are by Michael Simonelli and the Charts & Leisure team.
Sam: Thanks so much to Stacey Colino and Jen Golbeck. If you have not rated and reviewed Tiny Matters, please do! We’re trying to grow and that really, really helps us. If you want another way to support the show and look really cool drinking your morning cup of coffee, tea, juice, whatever, we have left a link to our Tiny Matters coffee mug. You can find me on social at samjscience.
Deboki: And you can find me at okidokiboki. See you next time.