364 



Injormatwn Storage and Neural Control. 



DNA 



Darwinian selection by Environment 



DNA — ^^ Messenger RNA — ^- RNA — ^- protein 



y 



Lamarckian modification by environnnent 



DNA 



Ontogeny 



Figure 1 



environment (Fig. 1). Just where in the sequence it acts, we do not 

 know; but a reasonable guess would be that it operates on the 

 messenger RNA, which is small in amount and relatively unstable, 

 to modify it in kind or amount or distribution. 



This, I think, reveals the nub of the earlier discussion between 

 Dr. John and Dr. Morrell. The extremely basic question arises: 

 Must we assume, or is it better to assume, that the environment 

 operates here by modifying the RNA (or other) molecules, which 

 is Lamarckianism; or is it possible that, as in genetic selection, 

 there is a large array of molecules, say a gene-like array of RNA's, 

 on which environment operates by some kind of selection? I am 

 sure nobody knows the answer at the moment; the situation does 

 not have quite the feel of selection to a biologist, but feelings can 

 be very wrong. Moreover, I would point out that, if molecular 

 modification is involved, we have not solved the critical problems 

 when we recognize that this occurs. It is important to get this 

 far; but some workers have talked as if identifying a memory 

 trace with a change in RNA is essentially the solution of the 

 engram. Rather, we are then at the very beginning of our troubles. 

 Exactly the same problems face us here that faced Lamarck in 

 getting the giraffe's neck longer. Let mc point out what these 

 problems are. The environment leads the giraffe to stretch his 

 neck; somehow stretching the neck generates a substance, or 

 influence, which goes from the neck to the gonads and produces 



