In existographies, Gerald Joyce (1956-) (CR:4) is an American RNA-world origin of life theorist noted, in chnopsology, for his 1991 high-cited so-called working-definition of life, which reads as follows: [1]

“Life is a self-sustained chemical system capable of undergoing Darwinian evolution.”

This definition is positioned, according to Robert Hazen, as being one of the better ones as found amid a recent origin-of-life text featuring an appendix of 48 different authorities, including: John Maynard Smith (any population of entities which has the property of multiplication, heredity, and variation), Stuart Kauffman (an expected collectively self-organized property of catalytic polymers), among other definitions, such as: “the ability to communicate”, “a flow of matter, energy, and information”, etc. [1]

Joyce’s definition, interestingly, has retained a certain amount of chain-like recitation popularity; having come to be known, as of 2007, supposedly, as NASA’s working definition of life, particularly in regards to their so-called exobiology program or search for extraterrestrial life. [3]

Difficulties
One of the unique aspects of Joyce's popular definition, is that it, in a way, attempts to intertwine, mold, or mend the disjunct between the Darwin view of natural selection and the chemical view of natural selection, in a seemingly innocuous manner—although not so innocuous to the more discerning eye. The gist of Joyce's definition is as follows:

Chemical Transformation (model)	\|	goes into →	\|	Darwinian Transformation (model)
"chemical thermodynamics" first law + second law		(4 BYA) (gap)		"survival of the fittest" DNA random mutation + natural selection

Joyce, in short, attempts to surmount the unbridgeable gap, with the use of the term "self-sustained chemical system" which is code, for those who don't know, for perpetual motion or rather perpetual motion of the living kind, i.e. a self-sustaining thing, reaction, or process, is a violation of the principle of inertia and the first law of motion (see: self terminology reform). The issue is summarized well by Roger Caillois’ famous 1973 quote: [4]

“Clausius and Darwin cannot both be right.”

In matters of dispute, of such universal importance, one always is advised to side with the "supreme law" of the universe, above that of all else, in the famous words of Arthur Eddington. In this case, nature "selects" and distinguishes between what is both "natural" and what is "unnatural" and chooses, in the end, those system transformation processes that result in free energy decrease differentials, system overall, over time. Hence, we side with Clausius and not with Joyce and his perpetual motion model of life.

Education
Joyce completed his BA in the biological sciences in 1978 at the University of Chicago and his MD-PhD in 1984 in neurosciences and chemistry at the University of California, San Diego.

Quotes
The following are related quotes:

“You have to build a straw man upon straw man to get to the point where RNA is a viable first biomolecule.”
— Gerald Joyce (1989), “RNA Evolution and the Origins of Life” [5]

References
1. (a) Joyce, Gerald F. (1995). “The RNA World: Life before DNA and Protein”, in: Extraterrestrials: Where Are They? (ch. 15, pgs. 139-151). (editors: Ben Zuckerman and Michael H. Hart). Cambridge University Press.
(b) Edited transcript of a public lecture entitled “The Dawn of Biology Current Views Concerning the Origins of Life”, presented at the Scripps Institution of Oceanography, La Jolla, California, 16 May 1991.
2. Hazen, Robert M. (2005). Genesis: the Scientific Quest for Life’s Origin (pg. 27). Joseph Henry Press.
3. Alkek, David S. (2007). The Self-Creating Universe: A Synthesis of Science, Philosophy, and Religion Creating a Theory of Universal Existence ("animate organism", chemistry, pg. 34). iUniverse. (ebook). LuLu.
4. (a) Caillois, Roger. (1976). Coherences Aventureuses. Paris: Gallimard.
(b) Thaxton, Charles B., Bradley, Walter L., Olsen, Roger L. (1992). The Mystery of Life’s Origin: Reassessing Current Theories, (ch. 7: “Thermodynamics of Living Systems”, ch. 8: “Thermodynamics and the Origin of Life”). Lewis and Stanley.
(c) Bushev, Michael. (1994). Synergetics: Chaos, Order, Self-organization (pg. 130). World Scientific.
(d) Prigogine Ilya, (1981). From Being to Becoming: Time and Complexity in the Physical Sciences. San Francisco: W.H. Freeman and Co.
5. (a) Joyce, Gerald F. (1989). “RNA Evolution and the Origins of Life”, Nature 338, 217-24.
(b) Irion, Robert. (1998). “RNA Cant’ Take the Heat”, Science, 279: 1303.
(c) Strobel, Lee. (2004). The Case for a Creator: a Journalist Investigates Scientific Evidence that Points Toward God (pg. 46). Zondervan, 2009.

External links
● Gerald Joyce – Wikipedia.
● Gerald Joyce (faculty) – Scripps.edu.