Peto's paradox

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Peto's Paradox is the observation, due to Richard Peto, that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. For example the incidence of cancer in humans is much higher than the incidence of cancer in whales. This is despite the fact that a whale has many more cells than a human. If the probability of carcinogenesis were constant across cells one would expect whales to have a higher incidence of cancer than humans.

Evolutionary considerations[edit]

The evolution of multicellularity has required the suppression of cancer. In order to build larger and longer lived bodies, organisms required greater cancer suppression. Evidence suggests that large organisms such as elephants have more cancer suppressor genes. The reason that intermediate-sized organisms have relatively few of these genes may be because the advantage of preventing cancer these genes conferred was, for moderately-sized organisms, outweighed by their disadvantages--particularly reduced fertility.[1]


  1. ^ Gewin, Virginia (21 January 2013). "Massive animals may hold secrets of cancer suppression". Nature News. Retrieved 12 March 2014.