In 1944, Erwin Schrödinger wrote “What is Life?”, a little book that inspired generations of scientists and became a landmark in the history of biology. There were two seminal concepts in that book: one was the idea that the genetic material is like an aperiodic crystal, the other was the view that the chromosomes contain a miniature code-script for the development of the body.

The example of the aperiodic crystal was used by Schrödinger to convey the idea that the molecules of the genetic material are arranged in a unique sequence, a sequence that a few years later became known as genetic information.

The example of the code-script was used to express the idea that there must be a miniature code in the hereditary substance, a code that Schrödinger compared to a Morse code with many characters, and was supposed to carry the plan of development of the entire organism. That was the very first time that the word ‘code’ was associated with a biological structure and was given a biological function.

The idea of the genetic sequence and of the miniature code led Schrödinger to a third conclusion, an idea that he expressed in the form of a prophecy: “Living matter, while not eluding the ‘laws of physics’ as established up to date, is likely to involve hitherto unknown ‘other laws of physics’, which, however, once they have been revealed, will form just an integral part of this science as the former”.

Schrödinger’s prophecy of new laws of physics turned out to be an illusion, and yet there was logic in it. It was based on the fact that Modern Biology emerged from a century-old battle against vitalism, and the argument that won that battle was the idea that “life is based on the laws of physics and chemistry”.

Schrödinger believed that only the laws of physics can explain life and the fact that the known laws do not achieve this goal can only mean that we do not know all of them, that there must be some hitherto unknown laws of physics. In reality, another possibility does exist: it is the idea that life does not require ‘new laws of physics’, but ‘new laws of biology’, i.e., ‘new codes’.

This is the solution proposed by Code Biology, a solution which amounts to saying that “life obeys the laws of physics and chemistry but is based on the arbitrary rules of its codes”. This is the first idea of Code Biology: life is based on arbitrary rules. The difference between matter and life is not due to the laws of physics and chemistry, it is due to the arbitrary rules of its codes.

Another conclusion is that the copying of the genes and the coding of proteins are different mechanisms and none of them can be reduced to the other because copying deals with information whereas coding deals with meaning. This implies that copying and coding are not only two different mechanisms of life but also two different mechanisms of evolution because a mechanism of evolution is the long term result of a molecular mechanism. More precisely, it implies that “evolution took place by copying and by coding, by natural selection and by natural conventions”. This is the second idea of Code Biology: the idea that coding is a new mechanism of evolution.

A third conclusion comes from the fact all codes are natural conventions, but not all natural conventions are codes. Many animals, for example, have the ability to interpret what goes on in the world and the faculty of interpretation is based on processes of abduction, not on coding rules. Another example is language, a faculty that creates arbitrary associations between objects and words with new types of natural conventions that are developed during the first years of life. Language, in other words, contains codes but cannot be reduced to codes. Interpretation and language appeared towards the end of the history of life but they too were based on arbitrary rules. This is the third idea of Code Biology: the idea that there are three different types of natural conventions in life, three different types of arbitrary rules.

Taken together, the three ideas of Code Biology provide a theoretical framework where meaning is a fundamental component of life, a component that exists at all levels, from all cells to all brains and to all cultures.