I twittered a bit about this article a bit earlier. It's about one of the oddest diseases in the world, the infectious mouth cancer that is currently decimating the population of Tasmanian Devils.
Not only is the article squicky, but exceedingly thought-proving to me about stuff that I have no practical need to ever know.

Cancer considered as an evolutionary process of cells:

By this means, the genetic character of the cell population gradually changes, and with such change comes adaptation, a better fit to environmental circumstances. What constitutes "the fittest" among clonal lineages within a pre-cancerous growth? Those that can reproduce fastest. Those that can resist chemotherapy. Those that can metastasize and therefore escape the surgeon’s knife.

By becoming infectious, the cancer has effectively made the Cronenbergian leap to being a new, parasitic organism with Tasmanian devils as hosts. The cancer's cells lineage is not the current host's body cells, but the cancer in the previous animal that transmitted the infection.

And how will this disease evolve next?