How rats became an inescapable part of city living | Hacker News Reader

How rats became an inescapable part of city living

nationalgeographic.com

87 pointsorcul51 comments

    > From Seattle to Buenos Aires, urban rat populations are rising—as much as 15
    > to 20 percent in the past decade, according to one expert. Charismatic
    > animals like elephants, polar bears, and lions are all in decline, yet
    > inside our cities, we find it hard even with extraordinary efforts to keep
    > rat populations in check.

One big reason for that is the removal of free-roaming cats and dogs from human habitats.

Free roaming cats and dogs have been a part of our society for as long as we've been forming cities, we only recently decided to remove them. Of course it's going to have the knock on effects we're now starting to see,

* vermin

* food waste

* wild animals venturing into cities

* etc.

They went into trash nowadays. Also cats preying on birds and decimating them. There's no ideal solution.

Because human cities didnt have gigantic midden piles before? There's no change there.

Can we bring back free-roaming cats and dogs then?

Cats & dogs can be fatal disease vectors (rabies).

And cats destroy local bird and wildlife populations. They don’t discriminate on what they hunt.

I grew up in Istanbul -- the cat city -- where free roaming cats are everywhere and have never seen a mouse in my life. I thought "mice in city" was a Medieval thing. Until I moved to Bay Area... And then I moved to Boston... Turns out there are mice all over the cities in US.

EDIT: Also recently I learned I'm allergic to mice. This went undiagnosed for 22 years until I moved into Boston.

Turkish here, can confirm.

34 years old, never once seen a rat in a city setting, living in the capital, Ankara.

Seriously, when I first moved into my new house in Boston, two months in, I saw a little mouse in my kitchen and I literally lost my shit. I've never even imagined seeing a freaking mouse in my living space. My roomies were like "ooh don't worry, that's normal. We can just call the exterminator tomorrow and it'll be all good." Apparently this is a totally normal thing in large cities in the East Coast like New York or Boston. Back in Bay Area it was normal to see mice or racoons in the streets, but I never even considered the possibility of seeing one inside my house.

It's interesting how tiny cultural differences (having cats in the city) can cause you to make such assumptions about human living conditions. Before moving to US, I would consider seeing mice an alarming and totally abnormal situation. It's like seeing a snake, or scorpion, or bat in your house.

I live in the country. I get mice in the house every winter. They can get in through the smallest crevice and they are attracted to the warmth.

Traps baited with peanut butter are effective. Mice are quite dumb.

When I lived in Texas, my co-workers who lived in the countryside would complain about scorpions. Scorpions liked one co-worker's closets especially, so she always had to shake out her clothes before getting dressed.

Scorpions are really scary looking, but they aren't as aggressive as you would assume based on the general fear of them.

When I find them in the house (Las Vegas), I just pick them up by the tail with chop sticks and put them outside.

That's interesting, I've heard similar things about Rome (where I've never been either).

My big worry about maintaining a large population of roaming cats is the impact on the bird population. I'm interested in hearing directly from someone who grew up in Istanbul - do you recall hearing or seeing birds often growing up?

Didn’t grow up there but visited. Istanbul is on the sea, so there are plenty of seagulls - aka “sea rats”, since they feast on trash. The few open / green spaces I’ve seen had plenty of birds, mostly pigeon-like if i remember correctly.

Been to Rome a few times too and that’s also pretty full of pigeons, afaik. The feline colonies in Rome are the stuff of legend, several Italian writers used them in stories. I bet they’ve been around since Roman times...

That makes a certain amount of sense. I'm not too surprised seagulls would be ok in the presence of cats. They're large, fairly powerful birds. Crows also seem more common in SF than they were in previous decades, and again, I'd expect crows to be more resilient facing a predator like cats. They're large, highly intelligent, pretty tough, and fight in groups.

Here's the thing - to a large extent, the birds you mentioned are urban birds, by and large. Seagulls are very coastal, but as you said, they eat trash, so the population will be very large in coastal urban areas. Crows also tend to flourish in urban areas. Pidgeons are notoriously urban creature, and while I've seen cats prey on them, they don't seem as vulnerable as smaller song bird species.

I'm interested in whether these smaller songbird species are present in Rome or Istanbul or other places that are cat-heavy, though there are of course factors other than cats (some regions wouldn't have these species regardless of the presence of cats).

I heard this too ("Adam ruins everything"). But there is a hugeg bird population in Istanbul (more than US cities I lived in). Mostly seagulls (thousands of them), pigeons, sparrow and crows which are all around the city. It's possible these are "city birds" resistant to cat attacks somehow and cats damaged other bird populations, though. I'm not educated enough to give a better answer.

https://outline.com/sPzj3G

“It is the tail,” says Laurinda Williams, who breeds rats on Long Island and sells them as pets. “If it weren’t for the tail, everyone would have rats.”

Definitely true.

The other thing about rat size... man IDK. I was in Panang Malaysia and saw a dead rat in a drain that blew my mind it was so large. It was no doubt in my mind over 2lbs. It was nasiating to see, and I’ve seen rats in DC, NYC, Paris. The articles claim of 1lb 13oz might be correct but it sure seems they must be extremely light for their size.

Back when I was a student I kept a couple as pets, as they were much more interesting than gerbils, mice, and hamsters. (That's about the size of pets we had space for.)

I do recall a few people were weirded out by their tails, but I never really understood it.

I'd be happy to keep rats again, they're intelligent enough to do interesting things, and learn from their environment. They can also respond to simple verbal commands - recognizing their names - and they're not at all prone to biting children, which is a good thing!

Seconded; I had a pair of rats until recently, and they made awesome pets: affectionate, smart enough to play with, and with distinct personalities while being pretty low maintenance (and willing to eat most of our food scraps). If my partner hadn't developed a skin allergy to them (which made handling them suck for her) we would for sure have acquired more when ours died.

Edit: in retrospect, I'm pretty sure that quote is from the breeder we used! She's doing hamsters and rabbits now as well.

I had some for a while too. I agree that they are really nice animals and a lot of fun but I also agree that the tails are a little freaky.

I still have holes in some bed sheets they chewed in :)

> “It is the tail,” says Laurinda Williams, who breeds rats on Long Island and sells them as pets. “If it weren’t for the tail, everyone would have rats.”

> Definitely true.

Is it, though? ;) There are other rodents with much more pleasant tails, and while I myself had a polecat-ferret when I was a kid, awesome pet, it sure as hell wasn't true everyone had them.

Was it bloated? Things bloat when they die.

Sounds like you saw the Greater Bandicoot Rat in Malaysia. Scary mofos.

I think I took a photo but only to show someone, probably deleted after that because I had trouble with it.

AMAZING food on that island, but then I kept thinking about these beasts running around at night. Didn't ruin the food for me, but I was happy to not think about it.

Those are gnarly rats!

> So the extermination industry uses anticoagulants, or blood thinners, which don’t affect rats for hours and don’t kill them for several days. The rats die slowly from internal bleeding. Corrigan hates to inflict such a death, but he fears outbreaks of disease. So he continues to lend his expertise to clients.

This is incredibly short-sighted thinking: Even if we ignore the horrible death it inflicts, what happens to the anti-coagulants after the rat dies?

Here's one example at the top of the page: https://www.mountainlion.org/actionalerts/043014CAab2657/043...

It's not like these poisons hit a precise target and magically evaporate: They remain in the environment, and then what goes around comes around.

Guess we’re lucky not to have rats here in Alberta.

I had no idea! Fascinating.

https://nationalpost.com/news/canada/the-stirring-story-of-h...

It's a little odd that the second paragraph of the article cites how rats "may have transmitted plague" and then links to an article titled "Maybe Rats Aren't to Blame for the Black Death".

Why?

The "common knowledge" is that rats (or their fleas) transmitted the plague. New research suggests this might not be the case.

Here is a link to that research: http://sci-hub.tw/https://doi.org/10.1073/pnas.1715640115

I think both phrases do a good enough job expressing the uncertainty of the rat's culpability in the black death: "X may have Y" and "maybe X didn't Y" are two sides of the same coin.

well, _something_ has to be there, right?

there's a lot of energy floating down there in the urban substrata, from sewage and trash going upward, so a food chain naturally emerges as opportunistic omnivores break the ground with predators following suite.

I don't agree with the idea that rats size is exaggerated in NYC. I have seen some at a building under construction at night that left me perplexed. A rat on steroids I'd say, walking like a pitbull..

I guess we’re lucky in Alberta to not have rats

Little known fact: rats, mice and pigs are our closest relatives, beyond primates. Which is why we test stuff on mice. And use pigs in developing medical devices.

This can't actually be true, because rats and pigs are not closely related to each other. Pigs are more closely related to whales than they are to rats, which means that if (say) we were more closely related to pigs than to rats, we would also be more closely related to whales than to rats.

In terms of taxonomy, primates are an order of mammals. It follows immediately that humans are equally closely related to all non-primate mammals. (That's not true either, as you can see by e.g. the designation of marsupials as an "infraclass", a level between class and order, but it's the first approximation to reality.)

I'm sure of it for rodents. Primates and rodents are "supraprimates".[0] Maybe I'm wrong about pigs, though.

0) http://www.els.net/WileyCDA/ElsArticle/refId-a0005306.html [see Images tab]

You say "that's not true either", but really, it was never true in the first place. Traditional taxonomy is bad at determining how related species are. If you want that, you look for evidences of common ancestors, or do DNA analysis.

I tried digging through Wikipedia articles on taxonomy, but it seems to be a bit of a mess, with different articles in the hierarchy using different, incompatible sources. It looks like rodents and primates are both members of clade Euarchontoglires, with common ancestors 85-95 mya.

https://en.wikipedia.org/wiki/Euarchontoglires

Clade Laurasiatheria is a sibling containing pigs, cats, whales, bats, and many others. Common ancestor with primates is listed as ~80-100 mya (yes, this number doesn't match the other one).

> Traditional taxonomy is bad at determining how related species are. If you want that, you look for evidences of common ancestors, or do DNA analysis.

"Evidence of common ancestors" is precisely what traditional taxonomy looks for. Clades at levels between the traditional taxa were developed by exactly that method. DNA analysis is the same strategy with new technology.

> It looks like rodents and primates are both members of clade Euarchontoglires, with common ancestors 85-95 mya.

> Clade Laurasiatheria is a sibling containing pigs, cats, whales, bats, and many others. Common ancestor with primates is listed as ~80-100 mya (yes, this number doesn't match the other one).

This sure looks like the approximation "primates are equally related to all non-primate mammals" isn't bad...

I clearly recall reading that DNA-based phylogenetic analysis indicated that primates and rodents have common ancestors that are more recent than common ancestors with other mammals. So in that sense, rodents are more closely related than, for example, dogs, cats, cattle, etc.

Pigs I may be wrong about. They're clearly more similar than dogs, cats and cattle. In embryonic development, for sure, and I remember that from dissecting a fetal pig. And there is the saying that embryology recapitulates phylogeny. But a quick search didn't come up with any DNA-based phylogenetics.

As you say, "traditional taxonomy is bad at determining how related species are". It's largely based on morphology, embryology and fossil evidence. But that can be irffy, given the thin fossil record, and the common occurrence of independent selection.

DNA-based classification is really the only way to get objective phylogenetic trees. And as we get them, we learn that lots of classical taxonomy is just wrong. And that's why reading about taxonomy online is so confusing. It's a mix of old and new, with lots of more-or-less uninformed speculation.

> Pigs I may be wrong about. They're clearly more similar than dogs, cats and cattle. In embryonic development, for sure, and I remember that from dissecting a fetal pig. And there is the saying that embryology recapitulates phylogeny. But a quick search didn't come up with any DNA-based phylogenetics.

The saying exists, but it is not based in anything other than wishful thinking. Ontogeny does not recapitulate phylogeny; that saying is the tongue map of evolutionary analysis.

https://en.wikipedia.org/wiki/Recapitulation_theory

> the shortcomings of the theory had been recognized by the early 20th century, and it had been relegated to "biological mythology" by the mid-20th century. This did not prevent its propagation into the 21st century in a variety of biology textbooks.

If you believe the page on euarchontoglires, you can see that pigs cannot be more closely related to humans than dogs, cats, and cattle, because all four of those human-other pairings have exactly the same common ancestor, the common ancestor of the euarchontoglires (the tree branch containing humans) and the laurasiatheria (the branch containing pigs, cattle, cats, and dogs). Any closer "similarity" between pigs and humans in specific is not driven by their evolutionary relationship.

> DNA-based classification is really the only way to get objective phylogenetic trees. And as we get them, we learn that lots of classical taxonomy is just wrong.

DNA-based classification is not conceptually different from morphology-based classification. They are both directly premised on the model of "descent with modification". DNA-based classification is generally superior because there is more information in the DNA than in the morphology. (Or at least, we recognize more information in the DNA than we do in the morphology.) But morphology-based classification did nearly 100% of the work of establishing modern taxonomy, and overwhelmingly DNA-based analyses confirm the existing morphology-based conclusions.

> traditional taxonomy is bad at determining how related species are

This is true in the sense of assigning a cardinal number to the relationship. ("Diverged 80mya.") It is false if your goal is only to assign an ordinal number. ("Humans are closely related to baboons, distantly related to rabbits, and remotely related to elephants.") The same objection applies to DNA-based taxonomy; we get cardinal numbers by assuming a particular constant-rate molecular clock, but the raw conclusions of DNA analysis are entirely ordinal.

> as we get them, we learn that lots of classical taxonomy is just wrong.

(quoting again to respond along another topic)

Notwithstanding the overall massive success of traditional taxonomy, there are some obvious weak points. They tend to derive from philosophical beliefs of the biologists rather than from failures of the morphology-comparing model. Two major biases that I'm aware of are the historical belief that taxa at the same level should include roughly the same number of extant species -- this was featured in a "teach the controversy" sidebar in a college biology textbook of my mother's -- and the stronger view that genera should contain more than a single species. Since the groupings prompted by these beliefs were not even intended to "cleave reality at the joints", it's not so surprising that they suffered under more objective analysis.

OK, I've largely conceded re pigs.

But do you agree that there's a good case that rodents are more closely related to primates than most other mammals are? Or do you believe that the evidence is too weak?

I could do some serious literature research, I suppose. But I didn't really set out to write a review.

I have nothing against the claim that rodents are closer to primates than other mammals are. I don't think that goes a long way toward explaining the use of mice in labs; it would be an equally strong argument for using gerbils, rabbits, capybaras...

I think mice are used because they're small and easy to keep, and because by now there's a lot of lab-mouse-specific infrastructure -- existing literature about them, special strains of mice bred for use in the lab, and so on. https://en.wikipedia.org/wiki/Laboratory_mouse#History_as_a_... suggests (in my eyes) that the use of mice is basically a coincidence.

The fact that they're at least as closely related to humans as other similarly cheap, non-dangerous animals is a plus, but I don't think it was the reason mice were used historically and I think it's only a minor contributor to the continuing use of mice today.

When you're really hoping to transfer a finding over to humans, you use monkey models, though I understand those are getting rarer under a combination of cost and animal-rights-activism issues.

From an historical perspective, I totally agree. Decades ago, when scientists settled on the mouse model, I don't believe that there was much (if any) solid evidence about evolutionary relatedness. As you say, mice were used because they were the least-expensive mammalian option.

Even so, it's arguable that predictive success for the mouse model helped drive its widespread adoption. Even so, just about all small mammals (e.g., rodents, shrews and moles) are more closely related to primates than large mammals. So maybe it was inevitable.

> ... getting rarer ...

Funny story. I was a grad student in the late 70s. And there was an animal-rights riot on campus. The primate lab was besieged. And some of us, whose thesis research depended on our building's mouse colony, were totally freaked.

That is not why mice, rats and pigs are used for scientific study, although mice do share about 80% of their dna with humans:

https://www.google.com/amp/s/amp.livescience.com/32860-why-d...

Your citation supports my argument:

> Another reason rodents are used as models in medical testing is that their genetic, biological and behavior characteristics closely resemble those of humans, and many symptoms of human conditions can be replicated in mice and rats. "Rats and mice are mammals that share many processes with humans and are appropriate for use to answer many research questions," said Jenny Haliski, a representative for the National Institutes of Health (NIH) Office of Laboratory Animal Welfare.

That's what you'd expect for for species that share a relatively recent common ancestor. Primates are even closer, of course, but they're much more expensive and problematic to manage.

> Your citation supports my argument

Part of, but part of it is refuted. Cats and other animals are genetically closer. Rats are preferred not for their genetic similarity, but for similar physiological responses and generic homogeneity.

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