Contagious cancer in Harper's magazine

Harper's magazine has a (too) long article on contagious cancer. Although the article focuses on Devil Facial Tumor Disease its main selling point is talking about cancer (any kind of cancer, not just freak contagious ones) in evolutionary terms. Cancer cells are another example that self replication is a driving force in nature. Once an object (in this case insubordinate cell) is able to self replicate, natural selection takes hold, and it's hard to look back.

Maley and Reid have more recently taken such thinking one step beyond evolution—into ecology. Along with Lauren M. F. Merlo (as first author) and John W. Pepper, they published a provocative paper titled “Cancer as an Evolutionary and Ecological Process,” in which they discussed not just tumor evolution but also the ecological factors that form evolution’s context, such as predation, parasitism, competition, dispersal, and colonization. Dispersal is travel by venturesome individuals, which in some cases allows species to colonize new habitats. Merlo, Maley, and their colleagues noted three ways in which the concept of dispersal is applicable to cancer: small-scale cell movement within a tumor (not very important), invasion of neighboring tissues (important), and metastasis (fateful).

Reading that, I remembered Devil Facial Tumor Disease and wondered whether there might not be a fourth way: transmissibility. An infectious cancer is a successful disperser. It colonizes new habitat. DFTD seems to be dispersing and colonizing, much as pigeons disperse across oceans, colonizing new islands. This wasn’t just evolution; it was evolutionary ecology.

I called one of the paper’s coauthors, John W. Pepper, an evolutionary biologist at the University of Arizona, and asked whether I was stretching the notion too far. No, he said, you’re not. If he could revise that paper again, Pepper told me, he would insert the idea that tumors evolve toward transmissibility.

Short update - another (short) article on looking at cancer as an evolutionary process can be found at "Survival Of The Fittest: Even Cancer Cells Follow The Laws Of Evolution", a summary of a recent article by Yeang et al.