Verticalization? It is the goal of the brain in an infant's 1st year of life. Get the body from the horizontal plane to the vertical plane in 1 year, through a series of developmental milestones that take the baby from non-mobile to mobile. That 1st year, that verticalization, is critical to happen in very a specific order in a very specific time sequence. The next goal of the brain after verticalization is communication (from age 1-2), and then from age 2-3 the brain's goal is socialization. You can see how a disruption in any of these 3 can create a cascade of effects to the growing child.