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May 28, 2014

On Peto's Paradox



"Peto's Paradox is the observation ... that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism."



Do blue whales seldom get cancer?

Being a cautious fellow I don’t know whether or not it is true that blue whales get less cancer than (say) mice but I do accept that fewer cases of cancer have been reported in blue whales than in smaller vertebrates. But caution also tells me that neither I (nor anyone else) has, at present, access to technology that enables one to observe an animal’s somatic cells as they are transformed to the cancerous state. Nor can we observe whether such cells are promptly extinguished by agents of an adaptive immune system (which all vertebrates possess) before producing cancerous daughter cells in sufficient numbers. Sufficient, that is, to cause death from cancer or to produce detectable symptoms. 
  
So, my starting point is different from others who have written extensively on this subject. My view is that—most probably—blue whales, because they consist of greater numbers of somatic cells, produce a greater number of cells transformed to the cancerous state than do mice but, as I will explain below, their greater size enables them to minimize production of detectable cancer.