2005 Annual Science Report
University of Colorado, Boulder Reporting | JUL 2004 – JUN 2005
Philosophical Issues in Astrobiology
My work continues to focus upon laying the logical and philosophical foundations for searching for extraterrestrial life in the absence of a definition of 'life’. Because we lack a general theory of living systems it is unlikely that scientists will recognize genuinely strange life for what it is if they come across it. Recognizing strange life presupposes an adequately general theory of life, and formulating the latter requires systematically searching for what Thomas Kuhn called “anomalies.” Anomalies are physical systems that resemble terrestrial life in provocative ways and yet are neither clearly living nor clearly non-living. The recognition of strange life thus begins with the verification and exploration of anomalies. In this context, biochemist Shelley Copley and I explored the possibility of anomalous (in essence, alien) forms of microbial life on Earth today. We successfully tackled the standard arguments (alternative molecular and biochemical possibilities for the origin of life, Darwinian competition with familiar Earth life, failure to detect them, etc.) against the existence of such organisms. Showing how preconceptions based on familiar Earth life can blind us to the possibilities for life in general underscores the importance and difficulties involved in searching for genuinely alien extraterrestrial life.
My work also focused on the search for a universal biology—a theory of biology that encompasses all life, wherever it is found and whatever it is made of. Drawing upon the history of chemistry, which achieved a universal theory of chemical substance based upon our experiences with chemical substances on Earth, I explored a number of parallels with our current understanding of biology. Of particular importance is the question of whether neo-Darwinian evolution, which is frequently touted as providing the foundation for such a theory, can do the job. My tentative conclusion is “no”. Among other things, the detailed molecular architecture of familiar terrestrial life (with proteins providing the foundation for morphology and nucleic acids for heredity) seems ideally suited for achieving biological change through natural selection. As software simulations of Lamarckian evolution suggest, it is possible that organisms with a different molecular architecture could utilize different physical mechanisms for achieving biological change.