Contrary to current thinking, it is the increase in number and complexity of synapse proteins–with the evolution of invertebrates and vertebrates–that accounts for more sophisticated thought in larger animals, not size alone, say scientists in the Genes to Cognition Program at the Wellcome Trust Sanger Institute.

Simple invertebrate species have a set of simple forms of learning powered by molecularly simple synapses, while complex mammalian species show a wider range of types of learning powered by molecularly very complex synapses.

The new findings will be important in understanding normal functioning of the human brain and will be directly relevant to disease studies.