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No. 80: Mar-Apr 1992

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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 Origin and Early Evolution of Life at Submarine Hydrothermal Vents," Eos, 72:59, 1991.)

From Science Frontiers #80, MAR-APR 1992. � 1992-2000 William R. Corliss