You might have to make up your mind to suspend judgment before trying to wrap your head around this one. All vertebrates use their bones and muscles to get about and obviously, the head is not the propelling mechanism, however – when the head is the first to be propelled, the body is compelled to follow. This is a very nice way to get about as it requires less effort and prevents potential mishaps caused by pushing or pulling, thrusting or busting forward with any other body part. No matter how complex a vertebrate, all varieties evolved from the same primitive blueprint; a simple spine which flexed from side-to-side in order to propel a mouth towards food. A body that got ahead of the head would either telescope upon itself (spineless creep!), or inadvertently bat the food away from the mouth (dummkopf!). Over time, developing muscles, fins, limbs or wings for evermore complex modes of movement over sea, land, or air – evolved vertebrates still retained this central role of the head in movement. Working in service of the head, a literal head-start ensures mind-blowing advantages!