Tasmanian devils have given rise to a weird new quasi-form of life: a cancer that spreads from animal to animal like a parasite. In tomorrow’s New York Times, I report on the latest analysis of devil’s facial tumour disease, published in this week’s Science. Scientists have now tracked down the cancer to its progenitor: nerve cells known as Schwann cells.
Now scientists can use this evolutionary history to design diagnostic tests for the cancer and perhaps even vaccines. Let’s hope they succeed–the cancer has wiped out 60 percent of all Tasmanian devils since 1996 and has the potential to drive the whole species extinct in a matter of decades.
For more on cancer as a new form of life, check out my earlier blog post on the only other documented case in the wild: a tumor that jumps from dog to dog. (The one major update to that post is that it now looks as if the tumor escaped its original dog host thousands of years ago, instead of hundreds as previously thought.) While dogs and Tasmanian devils are so far the only known hosts to these sorts of cancer, free-ranging tumors may actually be more common than we know right now. They may be particularly likely to arise in small, inbred populations. The similar immune systems of these animals may be easy for the cancer to evade, allowing it to spread quickly. Another hint that infectious cancer isn’t all that rare is the violence with which we reject transplanted organs. Why should our bodies be so well-primed to attack the cells of other humans? One possibility is that invasive cancers have been a long-term threat to the health of our ancestors.
(And for more on cancer as an evolutionary disease, see my article in Scientific American, reprinted in The Best American Science Writing 2008 )
Reference: EP Murchinson et al, “The Tasmanian Devil Transcriptome Reveals Schwann Cell Origins of a Clonally Transmissible Cancer.” Science http://dx.doi.org/10.1126/science.1180616
[Update 12/31 3 pm: Headline de-apostrophed.]
December 31st, 2009 at 2:38 pm
The malignant dog article also spawned an interesting letter in Evolution & Development:
http://www3.interscience.wiley.com/journal/118546199/abstract
My vet students read and discuss it; thoroughly enjoyable –and bizarre stuff to ponder!
December 31st, 2009 at 8:35 pm
All I know is that his (or her) front feet make me feel like I need to get my vision checked.
December 31st, 2009 at 10:30 pm
Wouldn’t cervical cancer and HPV also qualify as another example of this?
December 31st, 2009 at 11:41 pm
Book recommendation time:
http://www.amazon.com/Tasmanian-Devil-Unique-Threatened-Animal/dp/1741143683/
Read it just a few weeks ago.
January 1st, 2010 at 12:17 am
Mark, HPV is a virus and not a cell.
January 1st, 2010 at 2:01 am
Mark: Don’t think so. HPV is just a virus that has an unpleasant side-effect of making pre-cancerous changes to DNA sequences. The cancer is not infectious by itself, the virus is (I’ll do a post about HPV in a sec I think, it’s a fascinating virus actually).
In the Tassie Devil case the cancer itself is the infectious agent, it’s very unusual! As Carl said, it’s probably because the Devils are so inbred. Having a similar genome between individuals (as well as a similar immune system) makes the cancer feel at home no matter who it’s infecting.
January 4th, 2010 at 12:22 pm
[...] their immune systems don’t recognize infectious cancer cells from another individual as foreign [Science News]. The same kind of phenomenon showed up in 2006 in [...]
January 5th, 2010 at 4:49 am
To Mark, I wondered the same thing about the facial cancer. This article explains that the cancer is not transmitted by a virus.
This discovery is very exciting!
http://sciencenow.sciencemag.org/cgi/content/full/2010/104/2
January 7th, 2010 at 6:40 am
[...] have been bubbling in the pipeline for some months now, and were finally prodded to the open by this post by Carl Zimmer about the facial tumour disease wiping out Tasmanian [...]