A very good book, even though you should not take it literally, quote from the preface:
Eventually the cerebral cortex appeared as an expanding new highlevel computer controlling the structurally lower levels of the nervous system, the lower builtin programs. For the first time learning and its faster adaptation to a rapidly changing environment began to appear. Further, as this new cortex expanded over several millions of years, a critical size cortex was reached. At this level of structure, a new capability emerged: learning to learn.
[0]: http://nekhbet.leary.csoft.net/biocomputer.pdf
Edit (further context):
To avoid the necessity of repeating learning to learn, symbols, metaphors, models each time, I symbolize the under- lying idea in these operations as metaprogramming. Metaprogramming appears at a critical cortical size-the cerebral computer must have a large enough number of interconnected circuits of sufficient quality for the operations of meta- programming to exist in that biocomputer. Essentially, metaprogramming is an operation in which a central control system controls hundreds of thousands of programs operating in parallel simultaneously.