The phylogenetic trees reconstructed from molecular data have led to the discovery that all living creatures belong to three primary kingdoms, or domains, because there are three types of cells in nature. The primary kingdoms are referred to as Archaea, Bacteria, and Eukaya, and their first representatives were the first modern cells that appeared on Earth. All known cells, on the other hand, contain a virtually universal genetic code, and this implies that the code evolved in a population of primitive (...) systems that preceded the first modern cells and is collectively known as the common ancestor of all life. This gives us the problem of understanding how the descendants of the common ancestor gave origin to the first modern cells. In this article it is argued that the appearance of the genetic code allowed the ancestral systems to translate genes into specific proteins, but their behavior was still ambiguous because they were unable to produce specific responses to the signals from the environment. To that purpose they needed to evolve signal processing codes, and here it is proposed that the development of these codes was a crucial step in the evolution of the first modern cells. (shrink)

The fossil record shows that the stromatolites built by cyanobacteria 2 and 3 billion years ago are virtually identical to those built by their modern descendants, which is just a part of much evidence revealing that bacteria have barely changed in billions of years. They appeared very early in the history of life and have conserved their complexity ever since. The eukaryotes, however, did the opposite. They repeatedly increased the complexity of their cells and eventually broke the cellular barrier and (...) gave origin to all living creatures that we see around us. This gives us one of the major problems in evolution: why have the prokaryotes maintained the same complexity throughout the history of life while the eukaryotes have become increasingly more complex? Here it is shown that a solution does exist, but it is based on experimental data that so far have largely been ignored. It is based on the discovery that, in addition to the genetic code, many other organic codes exist in living systems. The potential to generate organic codes was already present in the common ancestor but was not transmitted indefinitely to all its descendants. After the genetic code and the signal transduction codes that gave origin to the first cells, the prokaryotes evolved no other organic code, whereas the ancestors of the eukaryotes continued to explore the coding space and gave origin to splicing codes, histone code, cytoskeleton codes, tubulin code, compartment codes, and sequence codes. This experimental fact suggests that the prokaryotes did not increase their complexity because they did not evolve new organic codes, whereas the eukaryotes became increasingly more complex because they maintained the potential to bring new codes into existence. (shrink)

The course of biological evolution is regarded by many authors as an ascending path toward higher levels of variety, complexity and integration. There are similar but partly conflicting accounts of the nature and causes of this ascending course. With the aim of reaching a unified conception I start by summarily reviewing three notable examples. These are, in their latest presentations, those of Hoffmeyer and Stjernfelt 2015, Szathmáry 2015, and Lane 2015a. Comparison of their commonalities and divergences, combined with further reflections, (...) leads to the following views: 1) cooperation between preexistent traits and processes is the primary determinant in the emergence of evolutionary novelty; 2) cooperation is a triadic relation similar to semiosis ; 3) regulation, the key element of both metabolism and replication, results from the cooperation of energetic and semiotic causation; 4) conceptual generalization and concrete generalization are fruits of cooperation. Conceptual generalizations spring from the cooperation of ideas. I believe these realizations supply essential elements for a unified view of the ascent of biological evolution towards higher levels of organization. Some of these conceptions are also applicable to similar ascending trajectories through the stages of cultural and technological evolution. (shrink)