rats – Rising Ape Collective

An excerpt from my favourite scene in the 1987 film, the Princess Bride:

Westley: Rodents of Unusual Size? I don’t think they exist. [R.O.U.S. attacks Westley] Westley: Ahhhh!!!

Why is that my favourite scene? Because I laugh every time I watch it. The R.O.U.S. is just so ridiculous-looking and shows up right after Westley disbelieves its existence.

For the devoted readers out there, you’re maybe wondering what my obsession with R.O.U.S.es is, because I’ve written about them before, but somehow they capture my imagination unlike any other strangely-proportioned creature. I think it has something to do with the comedic effect of reversing the expectation of something cute.

Rodents of Unusual Size: They do exist. Image from the Princess Bride — Rodents of Unusual Size: They do exist. They are definitely not cute. Image from the Princess Bride

The R.O.U.Ses from the Princess Bride have come to set the standard for overgrown rodents, but sometimes reality is stranger than fiction.

The largest discovered member of the rodent family (membership to which depends on having a pair of razor-sharp, ever-growing incisors), Josephoartigasia monesi is estimated to have been the size of a bull.

Reconstruction of head — A reconstruction of *J. monesi’*s skull based on the bones that were recovered. Image by Andres Rinderknecht & Ernesto Blanco

Since only its skull was discovered, the weight of this creature has been debated. The original discovery paper pegged the mass of the monstrous mulch muncher at 1211kg on average with a maximum of 2584kg. To put that into perspective, that’s anywhere from 1 to 4 dairy cows. A more recent study, however, showed that depending on the part of the skull you use to predict the mass of the full creature, J. monesi could have weighed from as low as 356kg (half a cow) to 1534kg (back up to the 2-cow range). Even if the creature was as small as 356kg, that still makes it nearly 6 times heavier than the current rodent heavyweight champion of the world, ~~Floyd Mayweather~~ the capybara.

In any case, it’s definitely big enough for a recent Science Magazine article to correctly use the term “Ratzilla”.

Ratzilla’s bite force was recently estimated up to 4000N, enough to outperform modern crocodiles and tigers. It was definitely a herbivore though, and is thought to have used its teeth as elephants use their tusks: to dig around for tasty treats.

Luckily for us, Ratzillas (Ratzillae?) no longer roam the plains of South America. They went extinct about 2 million years ago, after 2 million years of rodent dominance. Interestingly, that makes them the contemporaries of terror birds, sabre-toothed cats, and giant ground sloths. Their size and sharp teeth probably made them tough prey items.

Just like the R.O.U.Ses in the Princess Bride though, they were probably susceptible to fire jets and swords.

And with this rodent rant written, I promise to not write about any more Rodents of Unusual Size for the remainder of this ABCs series.

By Jonathan Farrow from The Thoughtful Pharaoh

I’ve never been a cat person, myself. They just seem a bit too contemptuous as a species.

Cats, aside from being aloof, clawed, and kind of mean, also form a necessary part in the life cycle of a single-celled protozoan called Toxoplasma gondii. This sneaky parasite can only reproduce in feline intestines but also finds its way into the tissues of pretty much all warm-blooded mammals. Its reach seems almost limitless and extends to more than half of the world’s bears, birds, cattle, cats, domestic chickens, deer, dogs, domestic geese, goats, mice, pigs, rabbits, rats, sea otters, sheep, and humans. And those are only the populations that were studied. Ever heard the expression that glitter is the herpes of the craft world because it gets everywhere? More accurately, glitter is the T. gondii of the craft world.

The life cycle of Toxoplasma gondii. Humans are on the left side of this diagram along with the rodents and small birds. Image from — The life cycle of *Toxoplasma gondii*. Humans, along with the rest of Noah’s menagerie, would be on the left side of this diagram. Felines, aka devilspawn, are on the right. Image from Wikipedia

I call it sneaky because T. gondii has been shown to alter the behaviour of its rodent hosts in order to make it more likely to be ingested. The physical mechanism for this is still under investigation and largely unknown but there are two interesting experiments worth noting. The first found that rodents infected with T. gondii are more active and more excited about new places, making them more likely to be noticed (and eaten) by cats. The second purports that rodent brain chemistry is altered so that the unfortunate rats finds the scent of cat pee sexually attractive. The scientific paper which explains this second theory is even titled “Fatal attraction in rats infected with Toxoplasma gondii”.

A lesson for rodents: don't listen to the parasite in your brain. Cat pee IS NOT ATTRACTIVE! Image from Wikimedia — A lesson for rodents: don’t listen to the parasite in your brain. Cat pee IS NOT ATTRACTIVE!
Image from Wikimedia user Lxowle

So we’re pretty confident that T. gondii can alter the behaviour of rodents, but what does it do to humans?

We’re not sure…

For those with weak immune systems or for the pregnant, a T. gondii infection can cause acute toxoplasmosis, a potentially fatal disease characterised by swelling lymph nodes, sore muscles, and flu-like symptoms. I wouldn’t worry about that too much because it’s about as lethal as the flu for those with regular immune systems.

For the rest of us, infection with this parasite is largely asymptomatic. There’s no way to tell whether you’re infected or not without a blood test. Unless you ask Czech researcher Jaroslav Flegr. He, along with a growing number of scientists, believes there is enough evidence to show that latent toxoplasmosis makes humans more thrill-seeking. According to a 2012 paper in the Journal of Experimental Biology, infected individuals are more likely to get into traffic accidents, score differently on personality tests than un-infected individuals, and infected men are taller on average with more masculine facial features.

Rodent and human brains are not so different, it turns out.

Japanese_litter_box_in_use — Patient Zero. From Wikimedia user Ocdp

If your cat got infected and you happened to get exposed while cleaning out its litter box, chances are that you are infected. Your cat’s poo is likely changing your personality. If, like me, you don’t and have never owned a cat, that doesn’t mean you’re safe from infection. T. gondii is really good at getting into your body and making its way to the central nervous system, where it acts the puppetmaster and, expecting you to be a rodent, makes you excited about new environments. All this so that you can be eaten and it can reproduce.

Pretty interesting, eh?

Tag: rats

R is for Ratzilla

C is for Cat Feces