From David Baxter, Greenhithe, Kent, UK
When considering the origin of life on Earth, note that it all runs on the same power system of ion gradients across a membrane. As this is universal, it must date back to a universal common ancestor (4 November, p 36).
How could such a system have developed on early Earth with only water, rocks, hydrogen and carbon dioxide to work with? The logical answer is that life arose where there was a natural ion gradient that could be exploited and alkaline hydrothermal vents, which you briefly touch on, are that place. Exploration of this idea has led to a lot of work, particularly by groups in Europe, which have produced a large body of biochemically sound literature.
