Introduction

Having covered in the previous chapter the basics of present-day living organisms and considered the limitations of life in terms of terrestrial and extraterrestrial environments, the present chapter addresses some of the issues surrounding the origin of life. We begin with general considerations about living processes and their relationship to the natural laws that govern the workings of the universe. In particular, self-organization seems to be a property of complicated physical systems, and computer simulations of such systems suggest the kind of bootstrapping necessary to build well-controlled biochemical processes from simpler suites of chemical reactions. We then move to more specific ideas about how life might have begun and examine the issue from two somewhat different points of view: that the origin of life lay in the primitive mimicking of cellular processes (the vesicle model) or that the essential point of origin lay in an RNA or slightly more primitive genetic-coding molecule (the RNA world).

Thermodynamics and life

Thermodynamics, introduced in Chapter 3, is the study of energy transfer in macroscopic systems. A fundamental principle that governs the transfer of matter and energy in both natural and artificial systems is called the second law of thermodynamics. It is most precisely expressed mathematically but, in words, it says that the capacity for a system to do useful work (move something) decreases with time, unless usable energy is pumped into it.