This article is within the scope of WikiProject Dogs, a collaborative effort to improve the coverage of articles related to Canidae and Dogs on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
For discussion of the difference between the origin of the cancer and the common ancestor of extant cancers, see Rebbeck et al (2009) Note that Murgia et al's (2006) estimate was based on divergence of tumors from each other, and so only only estimates the time of the common ancestor. Especially note that Murgia et al say:
Whether this time period represents the time the tumor first arose or whether it represents a later bottleneck in the tumor's dispersion as a parasite cannot be resolved.
"Transmissible Dog Cancer Genome Reveals the Origin and History of an Ancient Cell Lineage" by Elizabeth P. Murchison, et. al, Science 24 January 2014: Vol. 343 no. 6169 pp. 437-440. DOI: 10.1126/science.1247167 -- AnonMoos (talk) 08:40, 5 February 2014 (UTC)