This book is the study of all codes of life with the standard methods of science. The genetic code and the codes of culture have been known for a long time and represent the historical foundation of this book. What is really new in this field is the study of all codes that came after the genetic code and before the codes of culture. The existence of these organic codes, however, is not only a major experimental fact. It is one of those facts that have extraordinary theoretical implications. The first is that most events of macroevolution were associated with the origin of new organic codes, and this gives us a completely new reconstruction of the history of life. The second implication is that codes involve meaning and we need therefore to introduce in biology not only the concept of information but also the concept of biological meaning. The third theoretical implication comes from the fact that the organic codes have been highly conserved in evolution, which means that they are the greatest invariants of life. The study of the organic codes, in short, is bringing to light new mechanisms that have operated in the history of life and new fundamental concepts in biology.

This book is the study of all codes of life with the standard methods of science. The genetic code and the codes of culture have been known for a long time and represent the historical foundation of this book. What is really new in this field is the study of all codes that came after the genetic code and before the codes of culture. The existence of these organic codes, however, is not only a major experimental fact. It is one of those facts that have extraordinary theoretical implications. The first is that most events of macroevolution were associated with the origin of new organic codes, and this gives us a completely new reconstruction of the history of life. The second implication is that codes involve meaning and we need therefore to introduce in biology not only the concept of information but also the concept of biological meaning. The third theoretical implication comes from the fact that the organic codes have been highly conserved in evolution, which means that they are the greatest invariants of life. The study of the organic codes, in short, is bringing to light new mechanisms that have operated in the history of life and new fundamental concepts in biology.

The genetic code appeared on Earth at the origin of life, and the codes of culture arrived almost four billion years later. For a long time it has been assumed that these are the only codes that exist in Nature, and if that were true we would have to conclude that codes are extraordinary exceptions that appeared only at the beginning and at the end of the history of life. In reality, various other organic codes have been discovered in the past few decades and it is likely that more will come to light in the future. The existence of many organic codes in Nature is therefore an experimental fact, but also more than that. It is one of those facts that have extraordinary implications. In this book it is shown that the genetic code was a precondition for the origin of the first cells, the signal transduction codes divided the first cells into three primary kingdoms (Archaea, Bacteria and Eukarya), the splicing codes were instrumental to the origin of the eukaryotic nucleus, the histone code provided a new regulation system in eukaryotic genomes, and the cytoskeleton codes allowed the Eukarya to perform internal movements, including those of mitosis and meiosis. It is shown, furthermore, that organic codes had a key role in multicellular life, in particular in the origin of animals, the origin of mind and the origin of language. The great events of macroevolution, in other words, were associated with the appearance of new organic codes, and we can easily understand why. The reason is that a new code brings into existence something that has never existed before because it creates arbitrary associations, relationships that are not determined by physical necessity. Another outstanding implication is the fact that codes involve meaning and we need therefore to introduce in biology, with the standard methods of science, not only the concept of biological information but also that of biological meaning. The research on biological codes, in conclusion, is bringing to light new mechanisms in evolution and new fundamental concepts in science. This research is the field of Code Biology, the study of all codes of life, from the genetic code to the codes of culture, from the origin of life to the origin of man.

The genetic code appeared on Earth with the first cells. The codes of cultural evolution arrived almost four billion years later. These are the only codes that are recognized by modern biology. In this book, however, Marcello Barbieri explains that there are many more organic codes in nature, and their appearance not only took place throughout the history of life but marked the major steps of that history. A code establishes a correspondence between two independent 'worlds', and the codemaker is a third party between those 'worlds'. Therefore the cell can be thought of as a trinity of genotype, phenotype and ribotype. The ancestral ribotypes were the agents which gave rise to the first cells. The book goes on to explain how organic codes and organic memories can be used to shed new light on the problems encountered in cell signalling, epigenesis, embryonic development, and the evolution of language.

Early Thoughts on RNA and the Origin of Life The full impact of the essential role of the nucleic acids in biological systems was forcefully demonstrated by the research community in the 1950s. Although Avery and his collaborators had identified DNA as the genetic material responsible for the transformation of bacteria in 1944, it was not until the early 1950s that the Hershey-Chase experiments provided a more direct demonstration of this role. Finally, the structural DNA double helix proposed by Watson and Crick in 1953 clearly created a structural frame work for the role of DNA as both information carrier and as a molecule that could undergo the necessary replication needed for daughter cells. Research continued by Kornberg and his colleagues in the mid-1950s emphasized the biochemistry and enzymology of DNA replication. At the same time, there was a growing interest in the role of RNA. The 1956 dis covery by David Davies and myself showed that polyadenylic acid and polyuridylic acid could form a double-helical RNA molecule but that it differed somewhat from DN A A large number of experiments were subsequendy carried out with synthetic polyribonucleotides which illustrated that RNA could form even more complicated helical structures in which the specificity of hydrogen bonding was the key element in determining the molecular conformation. Finally, in I960,1 could show that it was possible to make a hybrid helix.

"Yet another cell and molecular biology book? At the very least, you would think that if I was going to write a textbook, I should write one in an area that really needs one instead of a subject that already has multiple excellent and definitive books. So, why write this book, then? First, it's a course that I have enjoyed teaching for many years, so I am very familiar with what a student really needs to take away from this class within the time constraints of a semester. Second, because it is a course that many students take, there is a greater opportunity to make an impact on more students' pocketbooks than if I were to start off writing a book for a highly specialized upper- level course. And finally, it was fun to research and write, and can be revised easily for inclusion as part of our next textbook, High School Biology."--Open Textbook Library.