Origin And Early Evolution Of The Metazoa

Several years ago, we realized that the most prominent ideas that had been ex pressed about the origin and early evolution of the Metazoa seemed to have been developed chiefly by zoologists using evidence from modern species without reference to the fossil record. Paleontologists had, in fact, put forth their own ideas but the zoological and the paleontological evidence were about the problem, seldom considered together, especially by zoologists. We believed that the paleon tological documentation of the first Metazoa was too scattered, too obscure to Western readers, and much of it too recent to have been readily available to our colleagues in zoology. Whether or not that was entirely true, we thought that a single volume reviewing the fossil record of the earliest Metazoa would be useful to many in both paleontology and zoology, especially since so much new informa tion has been developed in the last few years. Some of this information has been summarized in general articles recently, but an overview of most of the field does not exist. We therefore organized this book in five parts so that the evidence could be placed in perspective and summarized and inferences made from it. Part I intro duces the previous hypotheses that have been proposed for the origin and early radiation of Metazoa. Part II consists of two summary chapters that set the sedi mentological, geochemical, and biological background to the known radiations of Metazoa.

Recently, new genes and their proteins that revealed striking new insights into the early evolution of multicellular animals have been identified and characterized from members of the lowest metazoan phylum, the porifera (sponges). The unexpected result was that the sequences obtained from sponge displayed high similarity to those found in higher metazoa; in consequence, it was concluded that during the transition from protozoa to metazoa the major structural and regulatory proteins evolved only once. The data gathered are now powerful arguments to establish monophyly of metazoa; in addition, new insights on the evolutionary diversification of metazoa were obtained.

This book embraces general problems of animal classification of animals and new information on their molecular sequences.

The interplay between Geology and Biology has shaped the Earth from the early Precambrian, 4 billion years ago. Moving beyond the borders of the classical core disciplines, Geobiology strives to identify chains of cause-and-effect and synergisms between the geo- and the biospheres that have been driving the evolution of life in modern and ancient environments. Combining modern methods, geobiological information can be extracted not only from visible remains of organisms, but also from organic molecules, rock fabrics, minerals, isotopes and other tracers. An understanding of these processes and their signatures reveals enormous applied potentials with respect to issues of environment protection, public health, energy and resource management. The Encyclopedia of Geobiology has been designed to act as a key reference for students, researchers, teachers, and the informed public and to provide basic, but comprehensible knowledge on this rapidly expanding discipline that sits at the interface between modern geo- and biosciences.

"Enthralling . . . breathtaking . . . Metazoa brings an extraordinary and astute look at our own mind’s essential link to the animal world." —The New York Times Book Review (Editors' Choice) "A great book . . . [Godfrey-Smith is] brilliant at describing just what he sees, the patterns of behaviour of the animals he observes." —Nigel Warburton, Five Books The scuba-diving philosopher who wrote Other Minds explores the origins of animal consciousness Dip below the ocean’s surface and you are soon confronted by forms of life that could not seem more foreign to our own: sea sponges, soft corals, and serpulid worms, whose rooted bodies, intricate geometry, and flower-like appendages are more reminiscent of plant life or even architecture than anything recognizably animal. Yet these creatures are our cousins. As fellow members of the animal kingdom—the Metazoa—they can teach us much about the evolutionary origins of not only our bodies, but also our minds. In his acclaimed 2016 book, Other Minds, the philosopher and scuba diver Peter Godfrey-Smith explored the mind of the octopus—the closest thing to an intelligent alien on Earth. In Metazoa, Godfrey-Smith expands his inquiry to animals at large, investigating the evolution of subjective experience with the assistance of far-flung species. As he delves into what it feels like to perceive and interact with the world as other life-forms do, Godfrey-Smith shows that the appearance of the animal body well over half a billion years ago was a profound innovation that set life upon a new path. In accessible, riveting prose, he charts the ways that subsequent evolutionary developments—eyes that track, for example, and bodies that move through and manipulate the environment—shaped the subjective lives of animals. Following the evolutionary paths of a glass sponge, soft coral, banded shrimp, octopus, and fish, then moving onto land and the world of insects, birds, and primates like ourselves, Metazoa gathers their stories together in a way that bridges the gap between mind and matter, addressing one of the most vexing philosophical problems: that of consciousness. Combining vivid animal encounters with philosophical reflections and the latest news from biology, Metazoa reveals that even in our high-tech, AI-driven times, there is no understanding our minds without understanding nerves, muscles, and active bodies. The story that results is as rich and vibrant as life itself.

The evolution of animal diversity is strongly affected by the origin of novel cell and tissue types and their interactions with each other. Understanding the evolution of cell types will shed light on the evolution of novel structures, and in turn highlight how animals diversified. Several cell types may also have been lost as animals simplified – for example did sponges have nerves and lose them? This book reveals the interplay between gains and losses and provides readers with a better grasp of the evolutionary history of cell types. In addition, the book illustrates how new cell types allow a better understanding permitting the discrimination between convergence and homology.