http://www.sciencemag.org/news/2018/05/trio-genes-supercharged-human-brain-evolution > A technique for growing these brain cortical neurons in a lab dish made it possible to track down more genes involved in brain expansion. > Three nearly identical genes could help explain how 0.5 liters of gray matter in early human ancestors became the 1.4-liter organ that has made our species so successful and distinctive. The newly identified genes could also help explain how brain development sometimes goes wrong, leading to neurological disorders.