Origin & Evolution of Life: September 2009

Humans might not be walking on Earth today if not for the ancient fusing of two microscopic, single-celled organisms called prokaryotes, NASA-funded research has found.

By comparing proteins present in more than 3000 different prokaryotes - a type of single-celled organism without a nucleus - molecular biologist James A. Lake from the University of California at Los Angeles' Center for Astrobiology showed that two major classes of relatively simple microbes fused together more than 2.5 billion years ago. Lake's research reveals a new pathway for the evolution of life on Earth. These insights are published in the Aug. 20 online edition of the journal Nature.

This endosymbiosis, or merging of two cells, enabled the evolution of a highly stable and successful organism with the capacity to use energy from sunlight via photosynthesis. Further evolution led to photosynthetic organisms producing oxygen as a byproduct. The resulting oxygenation of Earth's atmosphere profoundly affected the evolution of life, leading to more complex organisms that consumed oxygen, which were the ancestors of modern oxygen-breathing creatures including humans.

May 21 - 23, 2010 Denver, Colorado and Dinosaur Ridge, Cretaceous Dakota Sandstone, Denver

The conference presents an important and novel review on microbial mats and the sedimentary structures they form in siliciclastic settings through Earth times, from the early Archean to the present. The meeting brings together the expertise and knowledge of an international panel of leading researchers to provide a state-of-the art overview of the field. The participants give a timely review of the current and most topical areas of research, essential for all scientists interested in this rapidly growing field. For more information: http://www.sepm.org/activities/researchconferences/microbial/microbial_home.htm Source: NAI Newsletter

Session Abstract: During most of the geologic past, life and the surface environments on Earth were profoundly different than they are today. In particular, it is generally accepted that the atmosphere was devoid of O2, or nearly so, until the "Great Oxidation Event" approximately 2.4 billion years ago. However, considerable uncertainty remains about the abundances of O2 and other oxidants during the first half of Earth history, as well as processes that constrained these abundances to seemingly trace levels. Emerging data should allow tighter constraints on Archean free oxygen concentrations, the variability of redox conditions at high temporal resolution, and the evolutionary and biogeochemical consequences of oxygenation. At the same time there is a need to refine existing proxies, assess their limitations, and develop new ones. This session will explore these issues. We encourage abstracts from a variety of areas ranging from analytical and theoretical geochemistry to genomics. For more information see
http://www.agu.org/meetings/fm09/program/scientific_session_search.php?show=detail&sessid=219 Source: NAI Newsletter