Meinschein et al. : Evidence in Meteorites of Former Life 577 



minor constituent of fish oils. To avoid the problems of total synthesis, Dean 

 and Whitehead-^^ used phytol, a biological product, and exchanged a single 

 hydroxyl group for a hydrogen atom to make phytane. Thermodynamically, 

 it is, also, difficult to deiine feasible conditions under which hydrocarbons in 

 terrestrial sediments may have formed abiotically. Amossow and Wasso- 

 jewitsch-"'' have observed that the ecjuilibrium temperatures calculated from 

 the abundances of various hydrocarbons in crude oils range between 0° and 

 225° C. for a Nebit-Dagh oil, 90° and 1075° C. for a Kara-Tschuchura oil, and 

 — 70° and 225° C. for a Kostschage oil. These temperature ranges are in 

 great disagreement with the temperatures that are believed to have existed in 

 sedimentary basins during petroleum formation. 



Research efforts carried out over a 100-year period have failed to provide 

 any evidence that abiotic, radiological, or chemical reactions were a significant 

 source of hydrocarbons in terrestrial sediments. A summary of the API 

 research on the origin of hydrocarbons notes the inability of radioactive 

 induced reactions to make products similar to those found in nature.^* 



C()iicl!isio)is 



Aromatic hydrocarbons have been identified as common constituents of 

 meteoritic and terrestrial sedimental extracts. Saturated hydrocarbons 

 isolated from the Murray and Orgueil carbonaceous chondrites have infrared 

 spectra, molecular weight ranges, and cracking patterns in the mass spec- 

 trometer that resemble those of sedimental saturated hydrocarbons. The 

 relative amounts of hydrocarbons and nonhydrocarbons, the infrared spectra 

 of the nonhydrocarbons, and the free sulfur contents of the benzene extracts 

 of the Orgueil and terrestrial marine sediments are similar. Except for the 

 relative simplicity of the aromatic fraction from the Orgueil fragment, analyses 

 of both the Orgueil and Murray extracts fall within the range of compositional 

 variations observed in terrestrial sediment extracts of plant and animal 

 hydrocarbons. 



Although further research may provide an alternative explanation for the 

 amounts and overall compositions of the benzene extracts of the Murray and 

 Orgueil carbonaceous chondrites, many similarities of these extracts to the 

 extracts of terrestrial marine sediments have been demonstrated. Lacking 

 another experimentally established explanation, we propose that the amounts 

 and compositions of the benzene extracts of the Murray and Orgueil are evi- 

 dence for biological activity in the parent body of these meteorites. Because 

 of the apparent stabilities of certain hydrocarbons in natural environments, 

 these compounds may provide a means of tracing the evolution of life in 

 primordial times. 



Acknowledgments 



The authors thank Brian Mason, R. F. Folinsbee, Lincoln LaPlaz, and E. P. 

 Henderson for providing the meteorite samples. T. C. Menzel, G. G. Wanless, 

 and J. J. Waters of Esso Research and Engineering Company ably assisted in 

 the analyses of some meteorite extracts. The authors thank the various 

 individuals who critically read the manuscript. 



