Introduction

There is a strange paradox in modern biology. On the one hand new discoveries are made at such a high rate that our science of life appears full of surprises and in a constant state of flux. On the other hand, all new findings are apparently accommodated within a theoretical framework that remains remarkably stable. Present day biology in other words seems to be in that phase of development that Thomas Kuhn referred to as normal science a phase in which an endless stream of novelties is smoothly accounted for by an unchanging paradigm.

And this is definitely not for want of alternatives. No efforts have been spared to provide different explanations of life, but none has withstood the rest of time. What makes us feel good about out present paradigm Which many call universal Darivinism ) is that on ly the truth or something very near the truth can resist so many assaults and outlive generations of cities. In such a situation, I find it almost embarrassing to suggest that our beloved paradigm is not as perfect as we like to think. But this is the message that is coming from nature and I had better tell you straight away the reasons that lead to this conclusion. The main points are three: the existence of organic codes, a mathematical model of epigenesist and a new theory of the call.

The organic codes

From time immemorial it has been thought that codes or conventions ; exist only in the mutable world of culture while nature is governed by immutable laws. The discovery that a genetic code is at the very heart of life came therefore as a bolt from the blue. And people rushed to anaesthetize it. The genetic code was immediately declared a frozen accident, and the divide between nature and culture remained substantially intact. The existence of other organic codes is, in principle, as natural as that of the genetic code, but its implications are perhaps even more revolutionary. The genetic code appeared on Earth with the first cells, while the linguistic codes arrived almost 4 billion years later, with cultural evolution. These are the only codes that modern biology currently recognizes, which is tantamount to saying that in 4 billion years no other code appeared on our planet. And if codes are relegated to the beginning and to the end of the history of life, we can safely say that 4 billion years of biological evolution went on with the sole mechanism of natural selection. In this book, however, we will see that there are many other organic codes nature , and that they appeared not only throughout the history of life but marked the main steps of that history, the steps which brought about the great events of macroevolution. But if codes exist they must have had origins and histories and above all they must have had a specific mechanism. Languages evolved not only by chance mutations of letters in their words but also by changes in their grammatical rules, and the same would apply to living organisms. We must conclude in  short that biological evolution was produced by two distinct mechanisms: by natural selection and by natural conventions.

From a logical point of view this is a straightforward conclusion but unfortunately theory and practice do not always go hand in hand. The idea of evolution by natural conventions was proposed for the first time in 1985, in a book of mine entitled the Semantic Theory of Evolution, but it did not have any significant impact (even if I am pleased to say that in a private letter Karl Popper called it revolutionary). Regrettably, people do not seem to associate the existence of organic codes with a mechanism of natural conventions as if one could exist without the other . Edward Trifonov, for example, has been campaigning in favour of sequence codes since 1988, and in 1996 William Calvin wrote a book entitled the Cerebral Code, but nobody called for anything different form natural selection. And there is a reason for that . the reason is that the word code has largely been used in a metaphorical sense, as have so many other words which have been borrowed by molecular biologists from everyday language.