A Thousand Brains: A New Theory of Intelligence

by Jeff Hawkins

There can be little doubt of the dominating influence of the Darwinian revolution of the mid-nineteenth century upon concepts of the structure and function of the nervous system. The ideas of Spencer and Jackson and Sherrington and the many who followed them were rooted in the evolutionary theory that the brain develops in phylogeny by the successive addition of more cephalad parts. On this theory each new addition or enlargement was accompanied by the elaboration of more complex behavior, and at the same time, imposed a regulation upon more caudal and more primitive parts and the presumably more primitive behavior they control. What Mountcastle says in these first three sentences is that the brain grew large over evolutionary time by adding new brain parts on top of old brain parts. The older parts control more primitive behaviors while the newer parts create more sophisticated ones. Hopefully this sounds familiar, as I discussed this idea in the previous chapter. However, Mountcastle goes on to say that while much of the brain got bigger by adding new parts on top of old parts, that is not how the neocortex grew to occupy 70 percent of our brain. The neocortex got big by making many copies of the same thing: a basic circuit. Imagine watching a video of our brain evolving. The brain starts small. A new piece appears at one end, then another piece appears on top of that, and then another piece is appended on top of the previous pieces. At some point, millions of years ago,...