We have known since the 19th century that abnormal “diversity” of cells makes cancerous transformation more likely. This is the traditional basis for the microscopic classification of tumors as benign or malignant. Maley, et al have applied Shannon’s diversity index to counting genetic clones of cells in pre-cancerous lesions. The more genetic diversity, the more likely the lesion is to become cancerous. Their statistical method may provide more reliable predictions than the traditional less-quantitative methods, but the basic concepts are very old, and they gain little from Darwin’s theory.
Yet Darwin’s theory is related to cancer, in a very important way. Darwin asserted that all natural integrated biological complexity arose by random variation and natural selection. Cancer does seem to grow in accordance with Darwin’s mechanism. The “variation” of cancer cells seems random, and cancer cells are certainly “naturally selected,” in the tautological sense that replicating cells eventually outnumber non-replicating cells. Darwin’s theory can be applied to cancer, trivially.
He gets it all quite correct in those two paragraphs, except for the bit on tautology and the last word, “Trivially.” Like a fool, Egnor appears to be stuttering “but… but… that doesn’t matter…” Sorry, but this observation that Darwin’s theory is related to cancer, which Egnor concedes, is THE point, not a trivial or irrelevant point.
Incidentally, a few weeks ago, he was saying that natural selection was irrelevant to medicine. Now he’s saying that it’s “trivially” relevant. Take note – the backpedaling has commenced!
But his confusion of the topic has not ceased, in any event – Egnor concludes with:
Cancer is the clearest empirical test of Darwin’s theory. Tumors, without exception, degrade biological function and integration. Darwin’s mechanism of “random mutation and natural selection” never gives rise to life. It destroys it.
Cancer is a phenomenon of cellular selection, trait acquisition in individual cells, etc.; cancer is not a phenomenon of an organism as a whole acquiring new traits, such as the formation of sickle-shaped red blood cells (i.e. sickle-cell anemia). It is a disease founded in the imperfection of organisms, maintained only by the fact that, mostly, the incidence of cancer is only in the older, non-reproductive populations; in young organisms, still at or before reproductive age, it does still happen, and is selected against. And as a cellular disease, Egnor has already agreed the obvious – that cancer cells which grow rapidly, avoid programmed cell death, avoid the immune response, escape the constrictions of surrounding tissues, etc., are SELECTED for (in the short term, at least), in the intravital environment.
So cancer IS a clear empirical test of natural selection – and one that resoundingly confirms that natural selection applies to all proliferating entities of biology.