... Science Frontiers ONLINE No. 80: Mar-Apr 1992 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Archaea: the living ancestors of all life forms Life's place of origin may soon shift from that long-favored "warm little pond" to undersea hydrothermal vents. "Important new discoveries on the properties of the early earth and atmosphere, including the frequency and size of bolide impacts, have strongly implicated submarine hydrothermal vent systems as the likely habitat for the earliest organisms and ecosystems, while stimulating considerable discussion, hypotheses and experiments related to chemical and biochemical evolution. Some of the key questions regarding the origins of life at submarine hydrothermal vent environments are focussed on the effects of temperature on synthesis and stability of organic compounds and the characteristics of the earliest organisms on earth. There is strong molecular and physiological evidence from present-day mircoorganisms that the earliest organisms on earth were capable of growing at high temperatures (about 90 C) and under conditions found in volcanic environments. These 'Archaea', the living ancestors of all life forms, display a variety of strategies for growth and survival at high temperatures, including thermostable enzymes active at temperatures about 140 C. Further molecular and biochemical characterization of the presently cultured thermophiles, as well as future work with the many species, particularly from subsurface crustal environments, not yet isolated in culture, may help resolve some of the important questions regarding the nature of the first organisms that evolved on earth." (Baross, J.A .; "Hyperthermophilic Archaea: Implications for the ...

... Scientific American. In the Table of Contents, we see words concerning this article that we never thought would be permitted in a mainstream science magazine. After first noting that 10 years ago it was generally agreed that all organisms evolved from a single ancestral cell that existed about 3.5 billion years ago, there comes the assertion that the Tree of Life: "is far more complicated than was believed and may not have had a single root at all." The article proper relates how the Tree of Life has its own evolutionary history. Twenty years ago, scientists had that single ancestral cell splitting into two main trunks: the prokaryotes (bacteria) and the eukaryotes (every-thing else). More recently, a third trunk has been grafted onto the Tree; namely, the archaea (microorganisms that look like bacteria but possess markedly different genes). The archaea favor extreme environments and, curiously, are more closely related to you and me than are the bacteria. But according to this article (by W.F . Doolittle), the triple-trunked Tree of Life is simplistic. One reason for this is that genes, once thought to flow only from parent to progeny, are now known to travel laterally. Species barriers are broken. Genes jump from trunk to trunk, from branch to branch, twig to twig. Of course, these jumps are seen primarily among the microorganisms. The real Tree of Life, then, is more like a snarl of vines--a Jungle of Life, a genetic Tower of Babel! Furthermore, no longer ...

... .. .report the discovery of high concentrations of hyperthermophiles [viz., bacteria] in the production fluids from four oil reservoirs about 3,000 metres below the bed of the North Sea and below the permafrost surface of the North Slope of Alaska. Enrichment cultures of sulphidogens grew at 85 C and 102 C, which are similar to in reservoir temperatures." Stetter et al favor the theory that these hyperthermophiles were injected into the reservoirs through: (1 ) drilling and secondary-recovery operations; and/ or (2 ) natural penetration via faults and seeps. They pointedly distance themselves from the idea, championed by T. Gold, that subterranean bacteria are actually permanent ancient residents of a deep subterranean biosphere. (Stetter, K.O ., et al; "Hyperthermophilic Archaea Are Thriving in Deep North Sea and Alaskan Oil Reservoirs," Nature, 365:743, 1993.) On the other hand, in their comments on the above paper, J. Parkes and J. Maxwell do not shy away from the theory that these denizens of hot, deep oil reservoirs are really indigenous life forms deposited with sediments in distant geological ages, surviving still and even evolving and conquering the infernal regions. They say: "The results presented do, however, provide firm evidence for the presence of a subterranean biosphere in oil reservoirs; moreover they are consistent with demonstrations of the existence of other deep biospheres in aquifers and marine sediments, which together indicate that the biosphere is not just a thin veneer on the geosphere." (Parkes, John, and Maxwell ...