In evolution thermodynamics, human being is a commonly used, but ill-defined, term or expression for a type of molecular structure called "human" that is argued to posses the properties of a “being” and to take part in the evolutionary process. The difficulty in using this term is that the idea of life or a “human being”, when viewed from the molecular evolution table perspective, is a fictional construct that falls apart in definition as one descends down the evolutionary tree to the roots, which are comprised of hydrogen atom precursors. [1] In this sense, the conception of a person as a “human molecule” becomes a more logical and correct perspective. [2]

References
1. (a) Thims, Libb. (2007). Human Chemistry (Volume One), (preview), (Google books). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two), (preview), (Google books). Morrisville, NC: LuLu.
2. Thims, Libb. (2008). The Human Molecule, (preview). Morrisville, NC: LuLu.