ABSTRACT
At present there exist two conflicting approaches to evolution, one is "historical-accidental" associated with "traditional neo-Darwinism", and the other is the "analytical-rational" approach. The "analytical-rational" approach has led to the understanding of important aspects of development and to the presention of a rational taxonomy more restrictive than the usual Darwinian genealogies. Genes are not amorphous materials on which evolution writes messages: they are the product of a rather complicated cellular machinery and should show the traces of the dynamics of such a machinery. Systems built of parts with low connectivity and with no dynamical conflicts have, in general, one or just a small number of optimal states and the system arrives at them, independent of the initial conditions and perturbations suffered along its history. At the protein level, immunoglobulins (Ig) are key elements in the mediation of the immune response.
