CARCINOGENESIS FROM INDEPENDENT EVENTS 169 



data of incidence for different countries, you will find that they are extroardinarily 



parallel. The fascinating thing which I don't understand, is that if you take the curves 



for the different countries, Japan, Israel, Wales, Scotland, etc., and simply displace them 



along the time axis, then they all fit together. In other words, the Japanese seem to be 



behaving exactly as if they were about 70 years older than the Israelis. Is this a latent 



period? 



UPTON: That's not a latent period, that's original sin! 



MOLE: WeU, I think if you assume that there is some exogenous factor, which you 



experience over a space of time, then differing amounts of this factor can explain the 



differences between different countries. 



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