"Comparing the molecular fingerprints of the developing ragworms' mushroom-bodies to existing information on the vertebrate pallium," Arendt says, " it became clear that they are too similar to be of independent origin and must share a common evolutionary precursor."
This ancestral structure was likely a group of densely packed cells, which received and processed information about smell and directly controlled locomotion. It may have enabled our ancestors crawling over the sea floor to identify food sources, move towards them, and integrate previous experiences into some sort of learning.
"Most people thought that invertebrate mushroom-bodies and vertebrate pallium had arisen independently during the course of evolution, but we have proven this was most probably not the case," says Tomer. Arendt concludes: "The evolutionary history of our cerebral cortex has to be rewritten."