Symmetry, Steering and the Brain
Animals have one of two kinds of symmetry – radial or bilateral, points out Max Bennett in A Brief History of Intelligence . Animals started by having radial symmetry. Why then did so many diverge into bilateral symmetry? Simple answer: Radial symmetry works fine if the approach is to wait for food. But it is a terrible setup if you want to navigate towards food. He expands on that. A creature with radial symmetry would detect signals from and move in all directions. Bilateral symmetry, on the other hand, is designed for movement in two directions – ahead and left/right. The former is very complicated; the latter is so much simpler. (Which is why human engineers have designed everything that moves with bilateral symmetry – cars, planes, submarines). While simpler on one front, bilateralism creates a new need – a decision-making capability . Which direction should one move in? Thus, all bilaterals, even the tiniest ones, have brains. Two rules are the min...