There is a very interesting article suggesting that cancers may actually be new species. In this study, chromosomal probes specific for each chromosome in a human cell are matched against chromosomes found in human cancers. In Figure 8 of this article, it is apparent that much of the DNA has been rearranged within the cancer cells in the form of translocations, i.e., massive amounts of DNA have been shuttled around the genome and reinserted into areas of other chromosomes where they do not belong. Furthermore, these rearrangements are significantly stabilized to the point that the cancer cell replicates them autonomously over countless generations, in effect, behaving like a newly formed species. This phenomenon can be readily explained by the compartmental models described elsewhere in this blog. Chromosomal DNA is maintained in discrete packages or cassettes which are capable of breaking apart from one another and reinserting elsewhere in the genome.
In the case of cancer, these cassettes could have originated from the fusion of a normal cell with apoptotic bodies (loose cassettes) from an adjacent dying cell. If this were to happen in vivo, the results could be disastrous, setting the stage for translocations and subsequent cancer formation as described in the article. Perhaps carcinogenic agents are involved in this fusion and reinsertion process by interrupting the normal apoptotic cascade, allowing for survival of individual cassettes which can then fuse with neighboring cells.
The implications for suggesting that cancers may be new species are profound because these kinds of mutations involve massive amounts of genetic material being shuttled around the genome. This parallels what may have occurred during the rapid radiation of species during the Cambrian explosion, the only difference being they are still occurring in complex multicellular organisms, generating “monster” species that cannot survive outside of the host and will die along with it unless transmitted to another host. However, what if one of these “monsters” was somehow able to generate a functioning organism? Think of the karyotypes of apes and humans. They are virtually identical except for several chromosomal rearrangements.
How could an ape or any other complex creature give birth to a newly formed species? In the case of an ape, the most likely explanation would involve translocations within the sex cells, i.e., fusing of chromosomes to reduce their number from 24 pairs down to 23. Such a translocation event would involve a “hot spot” or weak point within the chromosome that is easily disrupted. Next, exposure of a community of apes to some kind of mutagenic event would need to occur to vastly increase the rate of this translocation event. This community would need to give birth to at least one “mutated” male and female to perpetuate the new species. These “mutants” would be attracted to one another based upon their mutual similarities, giving rise to offspring.