The Science Pawdcast

Episode 35 Season 7: Coffee, Cats, And The Science Between

• Jason and Kris Zackowski • Season 7 • Episode 35

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Coffee may nudge biology, but only within limits. We dig into new research suggesting that three to four cups a day align with longer telomeres for people with severe mental illness, then challenge the hype with the caveats that matter: observational design, smoking as a confounder, wildly different cup sizes and brew methods, and the reality that more caffeine can erase potential benefits. We translate the science into practical guidance—why moderation beats megadoses, how 400 mg per day became a sensible upper bound, and where sleep and stress fit into the bigger picture of healthy aging.

Then we pivot to a feline mystery that spans millennia. Long before house cats padded through Chinese homes, leopard cats were the stealthy mousers around early settlements, drawn by grain and the rodents it attracts. Using mitochondrial DNA from ancient remains—paired with clues from art—we trace the species shift around the eighth century as domestic cats, descended from the African wildcat, traveled the Silk Road and found their place beside people. Tameness, tolerance, and a knack for living close to humans helped them outcompete their wild cousins in a world reshaped by trade and urban life.

Across both stories runs one thread: human routines create niches that biology rushes to fill. Our cups change our days at a cellular level, and our granaries and roads alter which animals share our spaces. If you love clear science, a bit of myth-busting, and the unexpected link between breakfast and ancient history, you’ll feel right at home here. If this resonated, follow the show, share it with a friend who loves coffee or cats, and leave a quick review—what surprised you most?


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SPEAKER_01:

Hello, science enthusiasts. I'm Jason Zakowski.

SPEAKER_00:

And I'm Chris Zikoski.

SPEAKER_01:

We're the pet parents of Bunsen, Beaker, Bernoulli, and Ginger.

SPEAKER_00:

The science animals on social media. If you love science and you love pets, you've come to the right spot. So put on your safety glasses and hold on to your tail.

SPEAKER_01:

This is the Science Podcast. Hello and welcome back to the Science Podcast. It's episode 35 of season seven. We hope you're happy and healthy out there. Chris, how are you doing?

SPEAKER_00:

I'm fantastic. How are you?

SPEAKER_01:

Are you enjoying this frosty weather we've had the last day or two?

SPEAKER_00:

Absolutely not. I went for school yesterday and it was nice out. And then I came home from school and I was drive I was I was walking to my vehicle and I thought, what happened to the nice weather? Warm weather. And when I say warm, I don't mean warm. It was probably minus five. And by the time I got to my vehicle at the end of the day, it was likely minus 20 degrees Celsius. And I was very sad. I wanted to have a nice weekend with warm. Again, the operative word is warm, but it's not warm. It's cold, but warmer than minus 20. And I think my wish was not meant to be.

SPEAKER_01:

No. No, it's not a bunch and it is very cold. We have a parade today that we're in. I don't know how well that's gonna go, but we're gonna try our best. Maybe we should put Beaker snow pants on. I don't know.

SPEAKER_00:

That's what I suggested earlier is for Beaker to wear her snow pants.

SPEAKER_01:

Anyways, what's happening on the Science podcast this week? We have two science articles. The first one is about how coffee intake may help with biological aging. It's interesting. And you and I both love coffee, so of course I want to be team coffee, so I did a little deep dive into this article. And the pet science one is about ancient cats in China. Were they the cats like we have here, or were they a different species? All right, let's get on with the show. There's no time like Science Time. This week in Science News, it's all about how coffee intake may help your biological aging.

SPEAKER_00:

But don't get too excited if you're a coffee drinker. There are some limitations to this study where it was an observational design and it which cannot prove cause and effect. But we're gonna get into that later. But that's just a little bit of a disclaimer. If you're like, whoa, I'm gonna go to my Starbucks or my Tim Hortons or my second cup and load up on the coffee.

SPEAKER_01:

Or circle K, or maybe just make it at home for pennies on the dollar.

SPEAKER_00:

Oh, I guess so.

SPEAKER_01:

Okay. The study comes from BMJ Mental Health, and the findings were published there. The long and short of it is that drinking three to four cups of coffee per day may help slow biological aging in people with severe mental illness. So I did leave the severe mental illness out. That's what they were looking at. There were no benefits when coffee intake exceeded four cups per day. I probably have on the average day three to four cups. Easy. And you do too, because you have a massive mug of coffee every morning. That's seven cups of coffee.

SPEAKER_00:

I don't think so, but I think it is equivalent to three to four cups. But I need a big cup of coffee in the morning and I drink it all day, and it's cold by the end of the day. I know you do, but I drink it all day.

SPEAKER_01:

I put mine in a Stanley thermos. Like we make a pot of coffee. I have a very small cup of coffee in the morning, and then you have your giant cup of coffee, and then I take the extra in my thermos, and that's what I drink. I have two or three more cups of coffee in the morning when I'm teaching. Oh, I look forward to those cups of coffee while I'm teaching so much, and the kids think it's so weird, but I don't care. Anyways, we should probably get back to the study. What this study found was that the level of intake is associated with longer telomeres, which is a marker of cellular aging. Chris, why do telomeres matter?

SPEAKER_00:

Telomeres matter because they are like protective caps at the end of chromosomes, similar to plastic tips on shoelaces. And I when I read this study, I thought about that. And I thought about little bricks playing with my shoelace or playing with my hoodie string. And I'm like, please don't eat off my plastic protector because those are, you know, worth their weight in gold. Telomeres naturally shorten with age, which contributes to cellular aging. And telomere shortening actually occurs faster in people with major psychiatric disorders like schizophrenia or bipolar disorder. Also, a little bit more about telomeres, they're highly sensitive to environmental influences, diet, and stress and inflammation.

SPEAKER_01:

So the idea that aging occurs more rapidly in those with mental disorders is very well understood. But also the hypothesis was that moderate coffee intake could slow those telomere shortenings because coffee has some good health effects as well. So the data came from the Norwegian top thematically organized psychosis study from 2007 to 2018. There was 436 adults, and 259 had schizophrenia, 177 had affective disorder. That's like what you mentioned, like bipolar disorder, major depressive disorder, and psychosis. The participants self-reported their coffee consumption and were grouped into zero a day, one to two, three to four, and five or more. And then additional information collected were things like smoking habits and years smoked. The participants drinking five cups per day were generally older. And individuals with schizophrenia tended to drink more coffee with those than those with affective disorders. If you're interested about smoking, 77% of them were smokers, and their average smoking history was nine years. And heavy coffee drinkers smoked significantly longer. Smoking influences caffeine metabolism, which can affect results. So they wanted to include that in previous studies. There's a lot of correlation between if you smoke, you have way more coffee in your day.

SPEAKER_00:

They looked at the telomere measures and how they measured telomere length was using white blood cells from blood samples. And the results across the coffee group actually formed a J-shaped curve. So the people who drank three to four cups per day had the longest telomeres, zero cups per day had the shorter telomeres, and more than five cups a day, bye-bye benefit. The benefit disappeared. Interestingly, participants that drank four cups per day showed telomere lengths equivalent to being five years biologically younger. And the associations actually remained after adjustments for age, sex, ethnicity, whether you were a smoker or not, the type of mental disorder, and also the current medications or treatments that you were taking or that the person was taking.

SPEAKER_01:

Some of the reasons coffee might have had this protective effect was it contains antioxidants and anti-inflammatory phytochemicals. These phytochemicals may reduce oxidative stress. Oxidation, of course, leads to damage and leads to the telomere shortening. Telomeres are highly vulnerable to both oxidative stress and the inflammatory process. So any way you can lessen those, your telomeres are not as damaged. So the authors of the study proposed that moderate coffee intake may help counteract factors that accelerate aging in psychiatric conditions. And as you mentioned, Chris, there were some limitations to the study. So don't go out and start quaffing a bunch of coffee and thinking you'll live forever.

SPEAKER_00:

Absolutely. So the observational design, again, cannot prove cause and effect, but they were missing pretty detailed information. What type of coffee was being used or drunk? Was it filtered, espresso? Was it instant coffee? Did the time of day of the consumption make a difference? You know what? All coffee isn't necessarily created equal. What was the exact caffeine levels per cup? But also you could be drinking other caffeinated beverages. There are some pretty highly caffeinated beverages out there on the market that may have had effect as well. Results also could be influenced by lifestyle factors, medication effects, and the interaction with smoking.

SPEAKER_01:

So coffee consumption worldwide is pretty common, and studies seem to show it is beneficial in moderation. So go coffee, but excess intake may increase oxidative stress and start to damage your telomeres. So generally, the advice is to stay at four cups of coffee or less.

SPEAKER_00:

But really, the measurement is 400 milligrams of caffeine per day, which you can get from other caffeinated source sources.

SPEAKER_01:

Now, they also didn't account for how much creamer you put in your coffee.

SPEAKER_00:

No, they didn't.

SPEAKER_01:

I know somebody who doesn't drink black coffee.

SPEAKER_00:

Interesting. And the other thing I was thinking about was diet, high in processed foods. That could be something that is harmful to the body, but that isn't part of this study. But it makes me think about who you are, what you eat, and drink from your head to your feet.

SPEAKER_01:

Coffee keeps me on my feet. I'll tell you that. I don't know where it's I don't know where I'd be without coffee. All right, that's science news for this week. This week in Pat Science, we are gonna look at the house cats of ancient China, because a new study came out that was really interesting in cell genomics. Early, early cats in China. And we are going through early life cycle cat in our house. That's Bricks.

SPEAKER_00:

He's a kitten. I've never had a kitten before, I don't think. Like that I've been taken care of all by myself. With you, of course, absolutely with you. But raising a kitten from a kitten, it's been a lot and quite a steep learning curve, that's for sure.

SPEAKER_01:

Yeah, but it's got a steep learning learning curve, and then it plateaus because like Bricks uses his litter box. Like that is a huge deal compared to a puppy. And Bricks is like pretty independent now. Like, honestly, he can probably survive all around our house where you would never leave a puppy that long young, unsupervised randomly in your house. We still watch Bricks everybody, but like he can jump around and he can get places and he can sleep places. I don't think he's destructive. Maybe some cats are, but not the same way a puppy might eat something and cause a problem.

SPEAKER_00:

Like Bernoulli.

SPEAKER_01:

Yeah, like Bernoulli. We had to watch that guy like a hawk. He ate everything. He still does.

SPEAKER_00:

And we still do. He still does. It's not I don't know. Maybe by the time he's two, maybe that'll be the golden age.

SPEAKER_01:

All right. So in this study, house cats apparently arrived in China around the 8th century AD. But China was not cat-free before then. There was a different species filling the ecological niche. New genetic evidence from the study reveals that leopard cats lived alongside humans in China 5,400 to 2,000 years ago, likely helping with rodent control. So that's the cool part. It was not the domesticated house cat. What the heck are leopard cats?

SPEAKER_00:

They're super cute. They're small, and they're spotted wild cats that are native to Asia. And they likely began frequently ancient human settlements to hunt the rodents attracted to the stored grain. And so this relationship can resemble commensalism, where animal where the animals where the cats benefited from humans without being fully domesticated. Now, before you think that they were cuddly, these early feline visitors were probably not cuddly or tame like modern house cats, but they exploited the situation by living near humans when it was advantageous to them, but not seeking human affection or to become domesticated. So where there's humans, there's waste or food and the rodents like that as a food source.

SPEAKER_01:

So these leopard cats just slunk about and ate the mice that were around the human settlements?

SPEAKER_00:

I'm not sure. I wasn't living 5,400 years ago, but the study seems to link human activity like that to the leopard cats hanging about.

SPEAKER_01:

They'd be nice to look at. How big are leopard cats? Do you know?

SPEAKER_00:

No.

SPEAKER_01:

I just Googled that. Are small, yeah, they are small. They're like four to fifteen pounds. So they're not any big yeah, they're small smaller than some cats. House cats. That's crazy. Okay. Yeah, they're yeah, they got long legs. They're roughly the size of a cat, like a house cat. Interesting. Anyways, the house cats we know of descended from the African wildcat, not the leopard cat. And that cat stuck around Africa and then went north to the fertile crescent. That's where it did really well in the deserty areas there. And there's been a long debate over when domestic cats got to China. In this study, they identified that some remains in China dated back to 730 AD, the Tang Dynasty. Now, these cats probably were brought by way of the Silk Road along the trade routes. The Chinese traders went west and saw some cute little kitties and brought them back. The genetic markers in all domestic cat remains point to Middle Eastern origins, consistent with those of the spread of this domesticated cat of that area.

SPEAKER_00:

So the researchers analyzed mitochondrial DNA from 22 ancient cat remains, and the samples range from 5,400 years ago, the Neolithic age, to the 20th century. And what they found is that the pre-AD 200 remains contained leopard cat MT DNA. And after 730 AD, it was house cat MT DNA. And so what that does is it supports a species shift from the leopard cat to the domestic cat over time. And I'm super excited. We've sent away Bricks' DNA to see what kind of cat he is or what region he is from.

SPEAKER_01:

Yeah, they also use beyond the DNA, which is interesting, the DNA from around the Tang dynasty shows white fur and short fur. And art from that time matches this, which is cool. So they used anthropology of artifacts to match it to the DNA. And 85% of all the cats painted during that time had some white fur. So those paintings help reconstruct what early Chinese domestic cats looked like. And any art before that time, like during the Han Dynasty, the cats definitely look more like leopard cats. They're the art depicted a spotted cat with a long striped tail and tall legs. So these are like those early village cats that weren't really pets but were hanging around. I think that's cool. They've cross-referenced the science with anthropology, which is itself a form of science.

SPEAKER_00:

Mm-hmm. That is really cool. Because it I guess it paints a broader picture of history. Leopard cats actually disappeared from human sites around the third century AD, and there was some possible reasons for that. It could have been because it was a chaotic historical period, lots of lots of welfare, an economic decline, and fluctuations in population, which could have impacted the changes in the available food for them. Stability returned, and the domestic cat had already arrived and competed more successfully because they were more tame and they were more compatible with living directly alongside humans. One thing I love about Bricks is that he comes in and he snuggles and he's he likes human affection. So yeah. And so domestic cats eventually replace the leopard cats in that ecological role.

SPEAKER_01:

So I guess as we close, interestingly, in this study, it just shows what we know. Animals will adapt to human environments when there's a benefit to them, where the benefit might outweigh some of the dangers or the costs. And you remember when we talked to the hummingbird spy scientist, there's hummingbirds that have evolved to live within our human environments. So that's cool too.

SPEAKER_00:

I know, but I really want to see uh nest with the tiny eggs. And I he stu he studies hummingbirds, he hangs out with hummingbirds all the time. And when I said to him, Hey, have you ever seen a hummingbird nest? He said no. And I thought, that's interesting.

SPEAKER_01:

Yeah, they're just so tiny.

SPEAKER_00:

They're just so tiny, you blink and you miss them.

SPEAKER_01:

Yeah. But we're talking about cats, not hummingbirds.

SPEAKER_00:

That's right. And we don't want cats to eat hummingbirds. Here's a spoiler leave your cat inside.

SPEAKER_01:

Yeah. Ginger's very cute, but she's definitely more leopard cat than a domestic cat because she's not as friendly as bricks. No, that's not true. She can be affectionate too.

SPEAKER_00:

On her own terms.

SPEAKER_01:

On her own terms. All right, that's pet science for this week. That's it for this week's show. Thanks for coming back week after week to listen to the Science Podcast. And a shout out to all the top dogs. That's the top tier of our Patreon community, The Popack. You can sign up in our show notes. All right, Chris, let's hear those names that are part of the top dogs.

SPEAKER_00:

Amelia Fete, Re Oda, Carol Hainel, Jennifer Challenge, Linnea Janet, Karen Cronister, Vicky Oteiro, Christy Walker, Sarah Bram, Wendy, Diane, Mason and Lou, Helen Chin, Elizabeth Bourgeois, Marianne McNally, Katherine Jordan, Shelly Smith, Laura Steffenson, Tracy Leinbach, Anne Uchida, Heather Burbach, Kelly, Tracy Halbert, Ben Rather, Debbie Anderson, Sandy Brimer, Mary Rader, Bianca Hyde, Andrew Lynn, Brenda Clark, Brianne Haas, Peggy McKeel, Holly Birch, Kathy Zirker, Susan Wagner, and Liz Button.

SPEAKER_01:

For science, empathy, and cuteness.

unknown:

Hopefully.