Is there any evidence of stable isotope patterns unique to biology?
Living systems tend to show a preference for one isotope over another (e.g. Carbon 12 Vs Carbon 13) whereas non-living systems either show no preference or show preferences different to those of life. The stable isotope patterns within ALH84001 have shown the presence of indigenous carbon components that have isotopic signatures in the direction of known biogenic carbon signatures. Overall, the carbon isotopic signatures of the non-terrestrial, possibly organic carbonates within ALH84001 are similar to the way in which life tends to prefer molecules containing one isotope of Carbon over molecules containing another. However, despite this similarity, this does not prove that living system are responsible for this carbon signature. (7) Are there any organic biomarkers present? Are there compounds present either alone or in mixtures that do not easily form under non-living conditions? Possible organic biomarkers are present within ALH84001 in the form of PAHs (Polycyclic Aromatic Hydrocar
