Just one year after the Apollo 11 moon landing, Robert Hazen, then a student at MIT, had the good fortune to work with a team of geologists studying the moon rocks that the astronauts had brought back to earth.
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In The Story of Earth, Hazen describes how this early experience led to his deepening understanding of the co-evolution of the earth and the moon, and led him and his colleagues at the Carnegie Institution for Science’s Geophysical Laboratory to study how life may have originated on earth as early as 4 billion years ago. In a starred review, we called it "a report of a fascinating new theory on the Earth's origins written in a sparkling style with many personal touches."
Is this a revolutionary advance over Darwin's The Origin of Species?
Not really. The earth's history is one of continuous dramatic change. The idea of evolution, which Darwin expounded so beautifully in the case of biology, is a universal characteristic. Evolution by selection is characteristic of the universe as a whole.
Evolution occurs whenever there is the possibility for sufficient variation in a system so that selection can occur over successive generations. This is true for the universe as a whole, for the earth and its minerals, for life and for information technology. All that is needed for a system to evolve is lots of different possible configurations, sufficient variation and a selection mechanism from one generation to the next.
Did Darwin have such a broad view?
Yes, he looked at vast expanses of time, and he followed the work of geologists such as James Hutton, who were studying how the earth evolved. In the early 19th century, scientists didn't see geology, biology and physics as separate sciences. The term science was only coined in his lifetime. Before that scientists were known as natural philosophers. That's how Darwin saw himself.
In Darwin's day, scientists didn't pigeonhole themselves. That kind of broad overview is what's needed today. In an important sense our work is not revolutionary. My colleagues and I are reconnecting to the tradition of natural science by connecting geological and biological evolution. For the first two decades of my career I worked as a geologist.
In Darwin's day, scientists puzzled over the distinction between vegetable and animal life. In the 1950s, Harold Urey, a Nobel Prize winner, and his student Stanley Miller used electric sparks and organic chemicals to simulate the effect of lightening on a “primordial soup.” In your book, you wrote that he produced “a suite of biomolecules stunningly similar to what life actually uses.” This appeared to support the view that life originated near the surface of an oceanic environment. Can you explain what led you to a different hypothesis?
As an outgrowth on the work with rock samples taken from the moon and asteroids, life was discovered to exist in extreme environments—superheated volcanic vents in the ocean, Arctic ice, acidic pools and stratospheric dust. Not only does it exist there, but it abounds in these environments.
In 1996, we began to consider how life might have emerged from chemical reactions in the deep, dark ocean, far from lightning or the sun's radiation. These studies led to our ideas about "mineral evolution.” We find that earth has changed dramatically over and over in its history.
With the new technologies that have been developed in the last 50 years, we are able to probe below the surface of earth and deep into its past
and have traced the evolution of minerals. Many teams of scientists have devoted their time and energy to exploring different aspects of this frontier.
The rate of continuous change in the history of the earth is dramatic. Only 8 percent of its history occurred in the last 500 million years. With the new technologies that have been developed in the last 50 years we are able to probe below the surface of the earth. We have found vast deposits of water and traced the evolution of minerals.
So this led you to wonder if it might also have originated there?
You and your colleagues at Carnegie produced a laboratory apparatus that demonstrated how life might have evolved under conditions that existed 4 billion years ago?
Yes, we employ high-temperature and high-pressure reactors that simulate earth's deep volcanic zones to study life's origins. Of course, it's very difficult when you think about the origin of life. It's difficult to put your finger on the exact moment when nonlife became life. We can trace steps of increasing complexity in the evolution of biomolecules, but where do you draw the line? So we have performed thousands of experiments to understand the transition from geology to biology.
And this involved the co-evolution of earth's minerals?
That's right. You cannot isolate the beginnings of life from the transformation of the minerals that support life. Their development is intertwined. That's why you can't isolate the study of geology from biology. The earth and life co-evolved.
You write that natural selection is a much more efficient driver of transformation than creative design. Can you explain why?
Selection is an incredibly powerful driver of innovation. Darwin's opponents accuse him of believing in randomness as the engine of change, but this is not so. Natural selection depends upon random variation, but the selection process is not random. Selection always favors solutions that work.
So-called "intelligent design" is much less efficient because everything must be preplanned. Natural selection is much more effective. It is a universal mandate.