Back to Volume
Paper: A Short, Critical Evaluation of Proposed Signs of Ancient Martian
Volume: 213, Bioastronomy '99: A New Era in Bioastronomy
Page: 303
Authors: Treiman, Allan
Abstract: Unambiguous identification of fossil traces of life (terrestrial or extraterrestrial) can be difficult or impossible. For instance, many shapes in the 0.1 - 10 micron size range can form biologically or abiotically. Published images of such shapes in ALH84001 have been Rorschach tests of our preconceptions: biologists tend to see biological influences; inorganic chemists or petrolgists see abiotic processes. Similarly, many complex carbon compounds can also form from biologic or abiotic precursors; some see degraded biological matter, other see organic syntheses. In this light, W. Schopf's checklist of characteristics for microfossils has not provided an answer to whether there are traces of ancient martian life in ALH84001; members of D. McKay's research group claim to have satisfied all these criteria, yet few biologists or meteoriticists have been convinced. The job of the exobiologist has been complicated greatly by recent recognition of life in nearly all low-T environments on Earth. If all our terrestrial systems are influenced by biology, how can we recognize a sterile system?
Back to Volume