Health and Disease 
principle on which it stores and retrieves information. One 
might, for example, get away with an analogue storage prin- 
ciple using traces which decayed slowly enough to match the 
average life-span. 
We can see that with any such mechanism there would be a 
problem of senility quite apart from the problem of replacing 
its parts. I wonder whether—through the selective process, or 
whatever it is, by which our brains became the machines they 
are—the nervous system may not have committed itself to 
principles optimally matched to the life-span of the whole body. 
Ifso, then to multiply our life-span might land us with a different 
kind of problem. 
Haldane: ‘These last three papers have largely been a 
complaint against the fact that we are prisoners under sentence 
of death. I think that is slightly unreasonable, because although 
man is only able to move for very short distances, all the people 
in the world between them have lived for considerably longer 
than is commonly thought to be the age of the universe. Yet 
if they had all been to the Antipodes and all those journeys 
were put together, they would just about have got to Alpha 
Centauri, the nearest fixed star. 
I am more worried by the prison than the sentence. Dr. 
Koprowski should come to India where we have any number 
of minor infections to deal with. Sulphaguanidine and emetine 
keep us on our feet if we survive the major diseases, which one 
can generally do now. Everybody here should read Act III, 
Scene 1 of Measure for Measure, in which the Duke of Vienna 
describes the molecular biology of his day: 
... Lhou art not thyself; 
For thou exists on many a thousand grains 
That issue out of dust. 
The speech is an admirable summary of what people thought 
was wrong with the human frame in Shakespeare’s time. 
Koprowski was perhaps, as he will probably be the first to 
admit, exaggerating a little. We have a new set of dangers in 
every generation, but seeing how well we have met many of 
233 
