Early life thrived despite earthly travails
Kerr, R.A.
Science 284(5423): 2111-2113
1999
ISSN/ISBN: 0036-8075 PMID: 10409069 Document Number: 508986
Part of a special section on evolution. The geological record reveals that early life experienced a series of narrow escapes in the first 2 billion years of the planet's history. Earth faced a harsh rain of meteorite impacts for its first half-billion years, was then continually on the verge of a worldwide ice age because the young Sun was faint and relatively cold, and then the planet's atmosphere was suddenly flooded with oxygen, threatening the anoxic life of the time and also perhaps sending Earth into the threatened deep chill. Life survived all these trials and emerged with resilience as its main trait, says J. William Schopf of the University of California, Los Angeles. The geologic approach to understanding early life unites ingenious methods to get more direct information about life from long-dead rocks and laboratory effects to explore the likely chemistry of early life or infer its genetic nature from the genes of living creatures.