Towards a common principle of biological control — How control weaves the string of life

This paper reviews the interplay between biology and control theory as a typical example of transdisciplinary knowledge integration. Control is a fundamental function of the living organism that works in all aspects of the life. Various control mechanisms are ubiquitously built-in at all levels of body structures of living organisms and work all the time to support the life. They are diversely different from one to another with different material bases and structures, but there are many reasons to think that have some common ground and design principles. It is argued that a unified approach is exploited by focusing on a biological way of dealing with environmental changes to investigate various control mechanisms of living organisms.The notion of compound control is proposed as a common principle of biological control based on the transdisciplinary nature of control theory.