World Population 
MacKay: Any attempt to predict public preferences in 
these matters will have to reckon with the effect which publica- 
tion of the prediction, or action based on it, can have on its 
validity. 
Crick: I doubt if the publication would have as much 
influence as that due to the actual changing sex-ratio of the 
population, though I wouldn’t like to say whether it would be a 
stabilizing influence or not. Moreover, surely this is partly a 
cultural phenomenon. There are countries in the world where 
at the moment sons are very desirable and daughters are not 
valued so highly. 
Brain: ‘The one thing we seem to agree about is that we 
males are highly selected survivors. 
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