Lecture Series
A Lecture Series Presented at the

The Dole Institute for Politics

Map to the Dole Institute
May 3rd, 7:30 PM
William Schopf
Professor of Paleobiology
Director of IGPP CSEOL
Department of Earth and Space Sciences
University of California, Los Angeles

The Earliest History of Life:
Solution to Darwin's Dilemma


In 1859, in his great work On the Origin of Species, Darwin stated the problem:

"If the theory [of evolution] be true, it is indisputable that before the lowest Cambrian stratum was deposited, long periods elapsed ... and the world swarmed with living creatures. [However] to the question why we do not find rich fossiliferous deposits belonging to these earliest periods ... I can give no satisfactory answer. The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained."

For more than 100 years, this missing record of the earliest chapters in life's long history stood out as among the greatest unsolved questions in all of natural science.

In Darwin's day, the oldest fossils were trilobites, lobster-like animals entombed in Cambrian-age rocks (known now to date from about 550 million years ago). But in the mid-1960s, understanding of the early history of life began to change as new finds - not of animals, but of tiny microscopic microbes - extended the fossil record into the remote reaches of geological time. Today, life on Earth is known to have emerged at least as early as 3,500 million years ago, some seven times earlier than was known to Darwin or to scientists even a few decades ago. Indeed, space-age technology now provides means to image such ancient fossils in cell-by-cell detail - fully, in three dimensions, even though they are completely embedded inside rocks - and to analyze both their cellular form and their organic, coaly, composition.

Given that our planet dates from about 4,500 million years ago, life here emerged quite early. No one knows whether such a speedy origin of living systems is typical of other planets, whether in our own Solar System or beyond. And no one knows whether the Cosmos is teeming with life yet to be discovered - there simply is no firm evidence to answer the question. But here at home, where there are hard facts to back such claims, we now know that that Darwin was right - the Precambrian world did, indeed, "swarm with living creatures." The dilemma posed by the "missing" early record of life has been resolved, the once unknown, and thought unknowable, has been discovered. That is the way of science.