Origin Of Life: What is the Problem?

With the development of the theory of Evolution by Charles Darwin and Alfred Russel Wallace in the nineteenth century, the focus of the debate over the origin of the organisms that populate the Earth changed. Prior to the development of the theory, no satisfactory scientific explanation for the complexity and diversity of species was available. The key question at the time was therefore: Why are there so many species, and how did they arise? Darwin's book, The Origin of Species, described the theory of Evolution and provided an answer to a major part of the question. It explained how lineages of organisms could adapt and diversify by the process of Natural Selection. However, it did not explain how life and the process of Evolution started in the first place.

There had been a long tradition of belief, dating back to Aristotle, in the Spontaneous Generation of life. However, in 1862, only three years after the publication of The Origin of Species, Louis Pasteur published the results of work which conclusively refuted the theory that micro-organisms could arise spontaneously from organic substances. Thus, at the same time as the debate over Natural Selection was raging, it had become no longer possible to believe in the Spontaneous Generation of life, and so attention began to focus on the origin of the first organisms.

The key processes required for Evolution are Reproduction, Variation, Heredity, Competition and Natural Selection. Although the specific mechanisms underlying Reproduction, Variation and Heredity were not understood in Darwin and Wallace's time, their insight was to observe these processes, along with Competition, and to see that Natural Selection and Evolution take place as a logical consequence.

The theory of Evolution continues to be developed, and there is debate over some aspects (such as the concept of Punctuated Equilibrium), but our understanding today is the same in its major respects as that described in The Origin of Species. We have good reason to believe that all organisms alive on the Earth today are descended from a Common Ancestor, and we can see how such an organism could give rise to the diversity and complexity of life we see today.

The question for those interested in the Origin of Life today is therefore not to do with how the process of evolution operates; it is to do with how it started. In particular: How did the processes of Reproduction, Variation and Heredity originate? What was the nature of the first evolving entities, and how did they arise?