Tasmanian Devils Catch Cancer

Photo Credit: PanBK/Creative Commons

The Tasmanian devil is a marsupial carnivore, best known to most Westerners through the Warner Brothers cartoons. It has acquired a vicious reputation because of its array of screams and shouts, its voracity (it is capable of gulping down 40% of its own weight in half an hour, and often does so as part of a group activity, in a sort of miniature shark feeding frenzy), its indiscriminate diet (small mammals, perhaps including animals as large as sheep; birds, reptiles, insects; carrion; other Tasmanian devils), and its powerful bite (nine times as powerful as a dog's, and capable of shearing through the bones of cattle; it routinely eats every scrap of an animal, not just the meaty part favored by bipedal predators). Until recently, however, the most compelling reason to fear the devil was its odor, said by some to be the most offensive smell produced by any animal. Supposedly it’s more nauseous than the scent of the skunk, and a powerful deterrent.

What’s happened recently: A contagious cancer has devastated devil populations. The cancer causes tumors on the face and in the mouth. The species, already in trouble, is now on the brink of extinction. More from Scientific American:

Unlike human and most other known mammalian cancers, Devil Facial Tumor Disease (DFTD) spreads from one individual to another individual through physical contact—from a bite or even a casual touch. 'Just imagine a human cancer that spread through a handshake,' said study co-author Stephan Schuster.

The particular habits of devils—like biting each other during sexual intercourse—helps spread the disease.

This cancer is unlikely to ever affect humans. On the other hand—and this is the scary part—there’s nothing to keep us from evolving our own contagious cancers.

And the flames of the tripods expired. And Darkness and Decay and the Red Death held illimitable dominion over all.
--“The Mask of the Red Death”
   Edgar Allan Poe

5 comments:

  1. So much to be learned about cancer. I read recently that a certain kind of prostate cancer can actually change its environment to make it more "cancer-friendly". I think it went something like this; doctors supress the production of a hormone/enzyme the cancer needs to develop, then cancer starts creating that substance itself.
    Also, a scientist recently described cancer as worthy of the title of "parasite". Granted, it kills its host and thus itself after a while, but, perhaps one day it will "leap" to another host when the old one is no longer useful?

    I lost someone to cancer, tho, so I don´t think I'll be reading much more on the subject...

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  2. That's fascinating stuff. I don't know much about cancer except what I learn from my friend Chris Battle, easily the most entertaining writer I've encountered on the subject.

    My doctor once remarked that, if we lived long enough, pretty much all men would get prostate cancer. It's simply what happens to prostate tissue eventually. Given that, it may be that the cancer isn't a parasite so much as the natural consequence of human existence. We're the caterpillar, it's the butterfly. Or I could be spouting nonsense again.

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  3. We're the caterpillar, it's the butterfly... now that's a whole new concept I had never considered!

    Not that it makes it any less frightening...

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  4. On the other hand—and this is the scary part—there’s nothing to keep us from evolving our own contagious cancers.

    It's improbable though, and this is actually one of the things that's depressing about the Tasmanian Devil story. Part of what keeps cancers from spreading between individuals in most species is that cells from another individual are generally regarded as intruders and the body's defense systems go to war and annihilate the foreign cells (this is a problem, of course, when we want the foreign cells to be accepted by the new host--e.g. when we're transplanting a kidney).

    Unfortunately and sadly, the Tasmanian Devil population has been in decline for millennia and the small remaining populations are approaching a monoculture with relatively little genetic diversity. And one consequence of this is that when one Devil exposes another to cells from its tumor (e.g. during a biting ritual), the cancerous cells aren't always foreign enough for the recipient Devil's immune system to treat them as invaders--it's almost as if cancerous cells in an existing tumor in the recipient Devil had merely metastasized.

    Humans, happily, have an enormous amount of genetic diversity. Less-happily, we've sometimes deliberately and frequently by accident reduced genetic diversity in quite a lot of species (in many cases, by causing breeding populations to shrink, yes; but we've also deliberately reduced biodiversity in agriculture, e.g. creating monoculture varieties of grain in which all plants are very nearly genetically identical, which is a good thing maybe 90% of the time if you want to feed people and a catastrophe the other 10% if the crop is threatened).

    Anyway, I think that's the real cautionary takeaway, in my humble opinion.

    And since this is my first comment here, let me just take a moment to say: I thoroughly enjoyed Deadly Kingdom, Mr. Grice, and thank you for writing it!

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  5. Thanks for the great comment, Eric. You taught me something. And thanks too for the nice words about Deadly Kingdom.

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