A team of Harvard researchers ran a series of experiments using a 3D printing technique that mimicked the growth and development of a human brain. The researchers believe that they have proven that the folded structure is simply a physical growth process and not a matter of biology. The team 3D printed a model of a foetal brain based on MRI data using several different layers of soft gel materials. The layers of gel were designed to swell and expand at different rates when placed in a specialized liquid solvent. The 3D printed model of the brain accurately developed folds on its surface in the same patterns as those observed in real human brain development as the outer layer compressed in on itself in response to the expansion of the inner layers of gel. You can read more about this amazing research over on 3DPrint.com: http://3dprint.com/117974/human-brain-folded-structure/