Origins of Life (CANTO)
How did life on Earth originate? Did replication or metabolism come first in the history of life? In the second edition of the acclaimed Origins of Life, distinguished scientist and science writer Freeman Dyson examines these questions and discusses the two main theories that try to explain how naturally occurring chemicals could organize themselves into living creatures. The majority view is that life began with replicating molecules, the precursors of modern genes. The minority belief is that random populations of molecules evolved metabolic activities before exact replication existed and that natural selection drove the evolution of cells toward greater complexity for a long time without the benefit of genes. Dyson analyzes both of these theories with reference to recent important discoveries by geologists and chemists, aiming to stimulate new experiments that could help decide which theory is correct. This second edition covers the impact revolutionary discoveries such as the existence of ribozymes, enzymes made of RNA; the likelihood that many of the most ancient creatures are thermophilic, living in hot environments; and evidence of life in the most ancient of all terrestrial rocks in Greenland have had on our ideas about how life began. It is a clearly written, fascinating book that will appeal to anyone interested in the origins of life.
A Short Book That Says a Lot, February 28, 2001
In 91 pages of text Freeman Dyson says some surprising and wonderful things, and turns around some conventional notions about the place of replicating molecules such as DNA and RNA in early life. His view is that they came later – perhaps much later – after metabolism was established in cells that reproduced sloppily and approximately, but had robust-enough homeostatic mixes that a split was usually successful. This view was approximately that of a Russian named Oparin 75 years ago, but the dazzle of the genome has turned almost everyone to thinking that precise replicators had priority in the development of life over haphazard metabolizers.
Dyson does not depend on hand-waving and vague argument to draw these conclusions. He reviews what is known and the main extant theories of life’s origin, then introduces his own, using a "toy model" that abstracts the chemistry and draws conclusions about steady-state solutions that might work. As befits a great theoretician, it is an elegant and powerful bit of theorizing, but does not wander from the constraints of the chemistry — as far as he knows. But Dyson is clear that the point of his model is to stimulate experiment, and that organic chemists will be the ones to judge the usefulness and viability of his assumptions.
Unless you are a physicist, you won’t follow some of his work in solving for the model, but you can trust the math and the physics when it comes from Freeman Dyson. Just glance at the equations and graphs, but follow the words in his model chapter and get a real feel for the kind of system that proto-life might have been.
He makes a good case for the essence of life being complexity, and that the conceptual purity and rigor of the gene has distracted us from the "tangled bank" that life at all levels, from bacterial cell to ecosystem to economy, seems to exemplify. Error tolerance — being able to carry on in the midst of junk and in spite of "mistakes" — seems to be more characteristic of life than exactness. That’s a pleasing notion in an uptight age.