The comparative approach to immunology can be traced to the era of Pasteur and Metchnikov in which observations regarding foreign recognition in invertebrates was a factor in the develop ment of the principal concepts that created the foundation of what now is the broad field of immunology. With each major experimental and conceptual breakthrough, the classical, albeit essential, question has been asked "are the immune systems of phylogenetically primitive vertebrates and invertebrates similar to that of mammals?" Somewhat surprisingly for the jawed verte brates, the general answer has been a qualified form of "yes", whereas for agnathans and invertebrate phyla it has been "no" so far. The apparent abruptness in the appearance of the immune system of vertebrates is linked to the introduction of the somatic generation of the diversity of its antigen specific receptors. Therefore the questions regarding the origin and evolution of the specific immune system revolve around this phenomenon. With respect to the origin of the system (aside from the or igin of the rearranging machinery itself, the study of which is still in its infancy) one can ask questions about the cellular and mo lecular contexts in which the mechanism was introduced.

This book on phylogeny and immunity reconstructs the history and evolutionary pathways of immunity among the various forms of life. The authors argue that the immunity could have evolved different adequately successful patterns in the animal sub-regnum which are strictly determined by the morpho-physiological possibilities of the animals. They state that the vertebrate type of immunity evolved only in the chordate branch. The publication devotes special attention to the arthropods and molluscs, as they have attracted more investigative efforts than any other invertebrate taxa. The authors selected Agnatha, Chondrichthyes, and Osteichthyes from the vertebrate taxa in order to show where and how the morphofunctional basis of the truly adapative immunity of the endothermic tetrapods gradually evolved. Each chapter gives the description of the origin and interrelationships of the representatives of the taxon in question. Also given are the main biological, morphological, non-morphological and immune attributes. Emphasized throughout the book is the central idea that immunological reactions are a part of the overall biological phenomena and should be studied only from this aspect. The authors express that the fields of comparative and evolutionary immunology will provide inspiration for further investigations in biomedicine in the near future.

Amphioxus Immunity: Tracing the Origin of Human Immunity covers a remarkable range of information about Amphioxus and its evolutionary context. This compilation of what is currently known about Amphioxus, with a sharp focus on its immune system, includes 13 topics, such as: Amphioxus as a model for understanding the evolution of vertebrates basic knowledge of immunology immune organs and cells of amphioxus a genomic and transcriptomic view of the Amphioxus immunity pattern recognition system in Amphioxus transcription factors in Amphioxus the complement system of Amphioxus the oxidative burst system in Amphioxus immune effectors in Amphioxus lipid signaling of immune response in Amphioxus apoptosis in amphioxus; primitive adaptive immune system of Amphioxus and future research directions This valuable reference book is loaded with information that will be useful for anyone who wishes to learn more about the origin of vertebrates and adaptive immunity. Provides new evidence on the origin of the adaptive immune system, the evolution of innate immunity, and evolution-stage specific immune defense mechanisms Not only presents the cells and molecules involved in the adaptive immune response in Amphioxus, but also characterizes the origination and evolution of the gene families and pathways involved in innate immunity Includes much pioneering work, from the molecular, genomic, and cellular to the individual level

This book discusses the evolutionary origin of immunoglobulins and T-cell receptors. The complex interactions between B and T cells in response to external antigens are the major focus of contemporary immunology. This book argues that these interactions may be relatively late evolutionary developments, due to the redeployment of a system invented for other reasons. In other words immunoglobulins did not arise in evolution to fight infection. The author theorizes that the system of variable region moleculars (VRM) arose at the time of the first vertebrates by an endogenous, self-organizing process. This primordial VRM system instituted a molecular ecology, a function so vital that from then on no vertebrate has been able to do without it.

The Evolution of the Immune System: Conservation and Diversification is the first book of its kind that prompts a new perspective when describing and considering the evolution of the immune system. Its unique approach summarizes, updates, and provides new insights on the different immune receptors, soluble factors, and immune cell effectors. Helps the reader gain a modern idea of the evolution of the immune systems in pluricellular organisms Provides a complete overview of the most studied and hot topics in comparative and evolutionary immunology Reflects the organisation of the immune system (cell-based, humoral [innate], humoral [adaptive]) without introducing further and misleading levels of organization Brings concepts and ideas on the evolution of the immune system to a wide readership

References.- Animals at the cell-aggregate body organization.- Porifera.- Humoral immunity.- Cellular immunity.- Conclusions.- References.- Diblastic animals.- Coelenterata.- Humoral immunity.- Cellular immunity.- The immune phenomena characteristics.- Conclusions.- References.- Protostomes.- Annelida.- The evolutionary significance of metamery and the coelom.- The cells.- The origin.- Humoral immunity.- Adaptive humoral immunity.- Cellular immunity.- Phagocytosis.- Cytotoxic reactions.- Transplantation reaction.- Adaptive cellular defense reactions.- Conclusions.- References.- Arthropoda.- References.- Chelicerata.- The cells and structures engaged in the immune reactions.- Humoral immunity.- Cellular immunity.- References.- Crustacea.- Hemopoitic structures.- Humoral immunity.- Cellular immunity.- References.- Insecta.- Blood cells.- Hemopoietic structures and their possible relevance to immunity.- Humoral immunity.- Inducible antibacterial peptides.- Cellular immunology.- Phagocytosis.- Encapsulation.- Transplantation immunity.- References.- Mollusca.- The hemopoietic tissues and organs.- The gastropods.- The bivalves.- The cephalopods.- Humoral immunity.- Cellular immunity.- Conclusions.- References.- Deuterostomes.- Echinodermata.- The coelomic derivatives of echinoderms and their possible role in immunity.- The immune significance of coelomic tubular and perivisceral systems.- The water vascular, hemal and perihemal systems.- Perivisceral coelom.- Other structures engaged in the immunity.- Humoral immunity.- Cellular immunity.- Regeneration.- Conclusions.- References.- Chordates/Urochordata.- The anatomical features of ascidians in regard to their possible immune significance.- The immune significance of the pharyngeal region.- Other structures engaged in the immunity.- The lymph nodules.- Body wall.- The neural gland.- Humoral immunity.- Cellular immunity.- Conclusions.- References.- Chordates/Vertebrates/Agnatha.- Origin.- The immunocompetent tissues and organs.- The possible thymus equivalent lymphoid structures of pharyngeal region.- The gut-associated lymphoid structures considered to be equivalent to the spleen.- Lymphoid tissues with the poietic capability supposed to be equivalent to bone marrow.- Other lymphohemopoietic tissues.- Humoral immunity.- Specific humoral immunity.- Cellular immunity.- References.- Chordates/Vertebrates/Chondrichthyes.- Origins.- The immunocompetent tissues and organs of chondrichthyans.- The thymus.- The spleen.- The gut-associated lymphoid tissue.- The immunocompetent tissues and organs of chondrichthyans comparable to the bone marrow.- The Leydig's organ.- Epigonal organs.- The lymphomyeloid structures of cranial region.- The kidney.- Development of lymphohemopoiesis in elasmobranchs.- Humoral immunity.- Specific humoral immunity.- Cellular immunity.- Specific cellular immunity.- Conclusions.- References.- Chordates/Vertebrates /Osteichthyes.- Origins.- The immunocompetent tissues and organs of osteichthyans.- The thymus.- The spleen.- The gut-associated lymphoid tissue.- The immunocompetent tissues and organs of osteichthyans comparable to the bone marrow.- The kidney.- Other structures.- Cells.- B Lymphocytes.- T Lymphocytes.- MHC Antigens.- Nonspecific humoral immunity.- Specific humoral immunity.- Nonspecific cellular immunity.- Cytokines.- Transplantation.- Cytotoxicity.- Cellular cooperation.- Conclusions.- References.- General conclusions.- References.

The history of science has shown the majority of hypotheses to be wrong. Sharp scientific criticism and strictly controlled experimental studies reject most of the hypotheses, leaving behind only a small number of assumptions and ideas. Nevertheless, each logical assumption should have its rightful place on the scientific “battlefield” supposed to assess its validity and determine its final fate. Even when a hypothesis is wrong, it still finds its place in the entire efforts of the humankind towards attaining the scientific truth. Namely, the wrong hypotheses serve largely to illuminate the way towards the correct ones or, at least, to show which way not to follow. Correct or not, ideas and hypotheses are necessary for the progress of science. They epitomize the efforts of human thought to elucidate nature without experimental verification and in the circumstances of scant data availability. Finally, hypotheses and ideas represent a symbiotic creation of our knowledge and imagination, the two most impressive appearances in the evolution of humans.