Summary arid General Discussion 359 



the system (the facial muscles), but this does not alter the principle. 

 The ontogenesis of an ecological community, i.e., the evolution 

 of the group roles and structures that form during community, 

 is similar. Such roles and structures can form only in certain 

 sequences and at certain stages in the interactions of the indi- 

 viduals that constitute the "cells" of society, and in time can 

 become irreversible. These include customs and rules, libraries, 

 and all sorts of appurtenances that form a morphological substrate 

 and channel social behavior. And, of course, the engram in the 

 brain is entirely comparable to horny skin or to bowed legs or 

 to wrinkles. It is interesting that a time-gated period of specifica- 

 tion has more recently been found not only in differentiation of 

 cells but in "imprinting" the nervous system and in fixation of 

 experience in still other areas. One is inclined to raise the question 

 of whether the units involved are in a sort of soft-shelled state, 

 like a molting crab, all at the same time, or whether different 

 units, particular neuron groups, become impressionable in separate, 

 temporally ordered periods. This also relates to the earlier argu- 

 ment on memory, and I shall come back to it. 



Now a word about malleability. This, you will remember, refers 

 to the sensitivity and the specificity of an organism relative to its 

 environment, particularly to the rain of information from the 

 environment. Over evolutionary sequences there develops greater 

 ability to respond, with greater chscrimination, to more kinds and 

 lesser amounts of such information. In fact, I would urge that 

 the major theme of organic evolution is what I have called the 

 epigenetic inode and is not just the ability to respond to the 

 environment, to learn, or to be molded by it; beyond that, it is 

 also the ability to be molded more and more easily — to learn to 

 learn. This learning to learn occurs, I think, at all levels and in 

 all systems in the course of "becoming," not only in evolution 

 and history but also in the individual, as psychologists well know. 



Several major inventions of life have favored this successful 

 increase in the ability to learn. Perhaps the first, certainly one of 

 the very early and important ones, was the invention of an array 

 of molecules able to replicate themselves and to produce other 

 particular molecules (in other words, the invention of an array 

 of genes with sufficient stability and sufficient mutability). This 



