Could diamonds reveal evidence for life… four billion years ago?
Studying anything about the ancient earth is extremely difficult. Rocks that formed four billion years ago will long since have been beat up, metamorphosed, or melted. Thus, to study the possibility of life four billion years ago, the authors of a paper in today’s issue of Nature turned to minute fractions of carbon included in zircon grains that were in turn included in a rock in Australia a mere three billion years ago. First, let us look at the age of this material. The included carbon is in the form of diamond and graphite, and may be even older than the zircon grains, but we can be confident that it is at least as old as the zircon. The zircons themselves can be dated using lead isotopes, and they ranged from 3.06Ga to 4.25Ga with a typical error range of 0.014 billion years. So we know we have some old rocks. Second, what can we learn from these ancient “girl’s best friends?” When one looks at the 13C isotope levels in the diamonds, they are substantially lighter than expected, w
