Immunity, Life and Dancing Starlings: A Physician's Perspective.

BACKGROUND: Immune function is the most basic physiological process in humans and indeed throughout the animal kingdom. Interestingly, the vast majority of textbooks of physiology do not include a chapter on immunity. Our species survival is dependent on the diversity of the immune response and the ability for antigen presentation and effector mechanisms to be enormously promiscuous. As physicians, we are likely all too aware of how brief our life span is and the myriad of diseases and events that shorten it. It is not surprising that we question where our life comes from and our relationship within the universe. Many hypotheses have been offered regarding the likelihood that intelligent life exists elsewhere. We propose that such issues be discussed in the context of basic biologic observations on earth, such as the sight of a dense flock of tens of thousands of starlings maneuvering in rapid twists and turns at dusk before settling in trees for the night. The mathematical likelihood for life elsewhere was proposed by Frank Drake in a classic equation whose 'thesis' has stimulated the search for alien civilizations and the nature of life. A fundamental gap in this equation is the presence of a diverse immune response, a feature essential for survival of Life, presumably also extra-terrestrially.