Hydrothermal ecosystemswater-containing terrestrial, subterranean and submarine high temperature environments -are the site of investigation for many biologists looking for primitive forms of life. This Ciba Foundation Symposium considered the evolution of hydrothermal ecosystems, which may have hosted the roots of life on Earth, and also serve as an analogue for the possible origin of life on Mars, where similar environments could also have existed, or exist.
The symposium brought together 27 participants from a mixture of disciplines. Biologists, geologists, palaeontologists and physicists gathered to pool their findingsthe first time that representatives from such diverse fields have met to discuss this issue.
Consequently, when Malcolm Walter (Macquarie University, Australia), Chairman, opened the meeting it was with a call for 'jargon-free' language and an emphasis on communication across disciplines. Aims of the meeting were not only to share information, but to use it constructively towards the planning of the next NASA missions to Mars, in which Jack Farmer (NASA Ames Research Centre, California) is directly involved. Mineral exploration geologists from the commercial field, scientists from NASA and research scientists from universities were able to share their expertise and understanding.
Hydrothermal ecosystems have become the most favoured sites in the search for the origins of life. Conditions there mimic, to some extent, the conditions on early Earth. There is both heat and water, and these conditions were abundant at around 3.5 Ga, when there was much greater vulcanism and a higher ambient temperature on Earth.
Dick Henley (Etheridge Henley Williams exploration, Canberra, Australia) described the geochemical activity of hydrothermal ecosystems, likening them to a biotic factory. The chemical profiles of hydrothermal vents are very diverse, but most maximise opportunities for evolving