The major means of propulsion through the alimentary canal is peristalsis.

Peristalsis

Explanation:

Peristalsis is simply a series of muscle contractions, these contractions occur in the digestive tractPeristalsis is also observed in the tubes that connect the kidneys to the bladderPeristalsis is an automatic and important process which moves: food through the digestive system, urine from the kidneys into the bladder  and bile from the gallbladder into the duodenum Peristalsis is a normal function of the body and can sometimes be felt in the belly (abdomen) as gas moves along

It is evolution, because we all have some of the same traits like eye color or shape or ears.