From the Beginning

There's a tremendous amount of evidence for evolution, but biologists are always looking for more. As with any delving into the past, this isn't easy to do. Time erases evidence. A number of wonderful sites of prehistoric cave art have been found over the years, from Altamira in the 19th century to Chauvet in the 1990s. But the experts still haven't come up with a plausible explanation for why this art was created (Curtis, 2006). Questions still remain: were these images meant to celebrate the diversity of life or to bring blessing upon a future hunt? Such questions are what make history both a frustrating and a fascinating endeavor, and no part of history is more frustrating or fascinating than investigating early life on earth. If it's hard to piece together what was going on in caves 20 or 30 thousand years ago, it's not surprising that figuring out what occurred 3 or 4 billion years ago would be much more difficult. The amazing thing is that it isn't totally impossible. Biologists, chemists, physicists, and geologists have worked together to come up with some plausible scenarios for the early years of life on earth. Sure, there's still much controversy about some of their explanations, but there has also been a lot of progress since the experiments by Stanley Miller and Harold Urey in the 1950s in which they attempted to recreate the chemical environment of the early earth. In this column, I want to explore several lines of evidence that together give us at least a sketchy view of what early life was like. That's not bad, considering that many of us can't trace our ancestors back more than two or three generations. Physicists and geologists agree that the earth is about 4.5——4.6 billion years old. There is also …