sentences:  Another theory suggests that post-canine megadontia resulted from the spatial reassignment by homeobox genes that increased post-canine tooth size while simultaneously decreasing the size of the canines.For the transition from megadontia to normal-sized post canine teeth and its inverse relationship to brain size, one hypothesis proposes that an inactivation of the MYH16 gene, which resulted in an increase in brain size, decreased temporal muscle mass.The decrease in muscle allowed for the brain to grow, which might have allowed early hominids to develop tools.