What hard evidence do we have today for a theory of
the origin of life?
The first area is comparative biochemistry along
the lines we have been following. The more we learn, the more the
Oparin-Haldane ideas make sense.
In addition, we have geological evidence from the
Earth's own history, including evidence for a primitive reducing
atmosphere and fossil remains of primitive microorganisms. These
fossils allow us to assign dates to the various biochemical steps
in the origin of life.
Finally, laboratory demonstrations, point out the
feasibility of the nonbiological synthesis of the molecules of life,
and of the formation of simple, organized chemical systems.
These considerations cannot prove the theories about
what actually happened billions of years ago, but they can give