The gastrointestinal tract is normally investigated using reductionism methods in human studies, where the focus is on each segment of the gastrointestinal system and the specific links between various parts of it. This helps researchers and clinicians to produce a simple relationship between the elements of the gastrointestinal tract based on clinical diagnosis and treatment. However, there is evidence indicating that the gastrointestinal tract has properties that are beyond function of the simple systems, such as, multiplicity of elements, network communication, (...) emergence, self-organization, sudden transition, nonlinearity, and adaptation, all of which are attributes of complex systems. It seems that the gastrointestinal tract is an appropriate candidate for complexity research. If the gastrointestinal tract is assumed as a complex system, then it would be more fitting to study the tract using holistic methods through interdisciplinary perspective. In the present paper, the features of the gastrointestinal that correlate to complex systems have been explained using physiological examples from studies done on human subjects. (shrink)