In reality there are many tensions occurring within any one person’s body at any one time. It’s like a symphony with all its various instruments. Some instruments (the base, drums, and horns) are very loud and some (the flutes, piccolos, and violins) are very quiet but they are all playing at the same time.

“The urge to simplify may have its roots in the wish to see the gut as a consequence of a single perfect design experiment whereas in reality the control mechanisms of the gut are the messy result of adaptive changes over millions of years that have created complementary and overlapping control systems. All these systems together reliably perform the task of moving and mixing gut content to provide us with essential nutrients.” 

Studying human anatomy from an evolutionary perspective, on some level, is almost a spiritual exploration because it provides us with a deeper understanding of the processes of change, which is always at work, always occurring, never ceasing.