The brains that exist today are the result of 0.6 to 1.2 billion years of metazoan evolution, and this vast span of time has allowed for a very large number of adaptive steps between our stem ancestors and today's animal cohort. Brain complexity is reflected in the complexity of its structural makeup. The combinatorial possibilities are staggering for a nervous system with only 302 neurons. The authors suggest that it is important to recognize the differences between brains and computers.
Individual transistors are homogeneous and nonadaptive.
Alternatively, it is at this time equally plausible that consciousness arises out of a novel feature of certain types of brains, some cellular or circuit property with a unique molecular, anatomical, or physiological signature. Only time will tell if and how the mind arises out of 'complex' brains.