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Posts Tagged ‘opossum intelligence’

I hate biology by Facebook meme. We’re living in a time of great natural history illiteracy, but we’re also living at a time in which people want to respect and learn about nature.

Virginia opossums are one of the most common species in the United States. They fit nicely in suburbia, and they are quite often encountered.

They are not cute, at least by conventional standards of cuteness, and when you encounter them, they stand with their mouths open in a gape threat display. They usually drool and generally look nasty.

So well-meaning people have tried to make the opossum look good, and in doing so, they have decided to bullshit people.

Bullshitting about any animal is a bad conservation strategy.

One common statement is that “many studies” or “a study” have shown that opossums are smarter than dogs and cats.

I had to hunt to find that citation! You’d think that such a groundbreaking discovery would be all over the clickbait science press, but no, it’s actually rather obscure study.

It was a study that was performed in the 1950s using the Fink arrow maze. It is really just a test to see if an animal can remember where it was fed before.  The researcher who did the research was a W.T. James, and he performed some other studies on the species, which did not show such a marked ability among the opossums. They are capable of learning.

Other researchers looked into the opossum’s intelligence and have generally found it lacking. Indeed, a 1965 study revealed that opossums were much worse than rats at learning how to follow a maze.

The 1950s study is the only one that compared dogs and opossums, and we live in a time in which a new cognitive study on dogs is released every month or so. Dogs are pretty intelligent animals. They have evolved some cognitive shortcuts that have allowed them to live in close concert with humans and to learn from humans.

So you have one study that shows opossums are more intelligent than dogs and you think that is worth posting on a Facebook meme?

It’s bullshitting people.

The truth is opossums don’t have to be smart to be successful. What makes them successful are two simple things: they reproduce rapidly and they will eat virtually anything.

They also can live their whole lives next to people and never really bother anything. Opossums are far less obnoxious to have around than raccoons are.  Raccoons tear things up. They open up garbage bins. They den in chimneys. They kill cats and eat their food.

A raccoon is an intelligent animal. They know how to open up chicken coops and eat all the chickens. They know how to open up gates and get into cornfields.

An opossum will just trundle around and not cause too much trouble.

It works for them.

And yes, they eat ticks and can prevent the spread of Lyme disease.

But they aren’t smarter than super social carnivorans.

So when you see these memes posted on Facebook about how wonderful opossums are, keep in mind that the claim about opossum intelligence being greater than dogs comes from a single study.

It’s bullshitting people. This study is useful, but it’s 60 years old. And no one has attempted to replicate it or tried to draw deeper meaning in the general comparison of cognitive abilities between dogs and opossums.

So yeah, one study. Interesting discovery, but it hasn’t been replicated. Also it doesn’t match what else we know about the two species.

It’s just one of those things you run across in a literature review and wonder about.

A much better understanding of opossums is they are primitive mammals. I don’t mean that they are inferior in this sense. I mean that they very similar to the first mammals that ever existed, and they have retained these primitive, generalized traits for tens of millions years.

That’s pretty amazing.

And it’s not bullshitting people.

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There’s a common statement on various websites related to opossums. It goes something like this:

“Opossums are not as stupid as people think. A study (or studies or tests) show that opossums are better at learning and discrimination showed them to be higher ranked than dogs.”

Okay. I’m going to call bullshit on this one.

Wanna know why?

I can’t find the study or test or any kind of peer-reviewed paper that says this.

And if I were a researcher making comparisons between the cognitive abilities of certain animals and the opossum wound up besting the dog, then I’d have very real questions about my methodology.

Here are the reason for my skepticism:

First of all, opossums have very small, very primitive brains. They are primitive mammals that retain much of the basal mammalian body type. They look very similar to basal placental mammals like the Cuban solenodon. Primitive mammals are unlikely to have many of the sophisticated cognitive abilities of more derived species, especially those that evolved to hunt cooperatively, like wolves and domestic dogs.

Secondly, no ethologist has recognized any sophisticated behavior in opossums. Opossums have been commonly kept as pets and as research animals for a very long time. They have been studied very closely, but no one is writing any great pieces of research on how opossums are able to reach such cognitive heights with such primitive little brains.

Now, there are many, many researchers looking into the cognitive abilities of dogs.  Studies have shown that dogs have very sophisticated social cognition, which they may have evolved through domestication. Dogs recognize the importance of human gestures, and they also know that when a person closes his or her eyes, the person cannot sense what the dog is doing.  There are dogs that respond to hundreds of words, and dogs can think abstractly.

If it were suddenly discovered that opossums could best dogs at these skills, it would be shatter almost everything we know about cognition in vertebrates. It would also fundamentally shift how we understand brain physiology, for an opossum’s brain is far more primitive and less complex than that of a dog.

So here’s my question to every site and book I’ve seen that makes this claim:

Where is the study that shows the impressive learning and discrimination abilities of opossums?

What’s its citation?

My guess is this study either doesn’t exist, or it is a simple methodology error in a multi-species comparative cognition study that the authors attempt to account for in the work.

And one study does not change the entire body of knowledge about a subject. It’s only when a particular study has a superior methodology that one can say it is paradigm shifting.

If this study does exist, it didn’t change the scientific community’s understanding of opossum versus dog intelligence.

If it did, you’d be seeing researchers working with large numbers of opossums to see how their cognitive abilities work.

And that’s simply not the case.

The old saw that states that extraordinary claims require extraordinary evidence certainly applies here.

And as far as I can tell, this is nothing more than an internet rumor that somehow grew legs.

 

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