Developmental Dynamics in Humans and Other Primates

Discovering Evolutionary Principles through Comparative Morphology

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“Jos Verhulst approaches human evolution with refreshing open-mindedness. In Developmental Dynamics he presents an astounding wealth of little-noted facts that assume surprising new significance as he develops his thesis. From the outset, Verhulst incorporates a spiritual perspective into his scientific exploration of the evolutionary process. Though some readers may not agree with his conclusions, all will find the rich content of his book extremely thought-provoking.”

Wolfgang Schad, author of Man and Mammals: Toward a Biology of Form;
Professor of Morphology and Evolutionary Biology, University of Witten, Germany

In this book, Belgian scientist Jos Verhulst presents the most thorough research to date elaborating an evolutionary theory first set forth by the Dutch anatomist Louis Bolk in the early twentieth century. This theory is based on the proposition that dynamic principles inherent in the development of individual organisms are also at work in animal evolution as a whole. For example: A chimpanzee fetus is strikingly similar to its human counterpart—its cranium is rounded, its face flat, and its hair is restricted largely to the head. As it develops, however, the chimp diverges from its original, humanlike form, assuming specialized apelike features. In a detailed comparative study of numerous organs, Verhulst shows that, unlike the other primates, humans retain their original juvenile form. Standing Darwin on his head, he concludes that humans have not descended from apes but rather that apes evolved by diverging from a humanlike prototype. He also shows that our human tendency to retain our fetal form (fetalization, or retardation) is complemented by further development (hypermorphosis) of such organs as the legs, heels, forebrain, and larynx through which we attain our eminently human capacities of upright posture, thinking, and speech.

In the last chapter, Verhulst sketches a broad view of how retardation and hypermorphosis have worked together in animal evolution. He speculates, for example, that vertebrates evolved from invertebrates when ancient sea squirts (a form of tunicate, a marine invertebrate) retained their larval characteristics and developed them further as they evolved into fish. Sea squirt larvae are free-swimming and resemble tadpoles. Their brain includes a light-sensitive eyespot, and they have a rudimentary spinal cord. In their adult stage, however, they are sessile filter-feeders with neither nerve cord nor eyes. Verhulst postulates that primitive tunicates like the sea squirt retained their larval characteristics (through retardation) and evolved (through hypermorphosis) into fish, the first vertebrates. Following in a tradition as old as Darwinism, he proposes that, from the very beginning of animal evolution, these dynamics have led progressively toward the emergence of the human form. In this view, the gradually emerging human prototype is seen as the driving force and central trunk of the evolutionary tree, as the wellspring from which the animal world has sprung.

“Jos Verhulst’s penetrating grasp of human development leads to a refreshing view of human origins. In a perceptive, lucid and lively account, he argues convincingly that there is more to evolution than just Darwinian natural selection. Following in the footsteps of Goethe and Bolk, Verhulst champions the view that evolution was guided by an intrinsic drive that has culminated in the human gestalt, and that the harmonious form of the human body is a reflection of what he calls our synergistic composition. No part of human anatomy is left untouched as Verhulst examines the impact of changes in the rates and timing of development as the source of our evolutionary heritage. He demonstrates most effectively that we are the product of both fetalization and hypermorphosis, which leave some traits less developed than in the ancestor, others more so, as growth is prolonged. And this he argues in a manner both compelling and eminently accessible. If you are in any way curious about our origins, then I invite you to read this book.”

Kenneth McNamara, author of Shapes of Time: the Evolution of Growth and Development;
Senior Curator, Invertebrate Paleontology, W.A. Museum, Perth, Australia

ISBN: 9780932776297

Additional information

Weight 20 oz
Dimensions 6.5 x 1 x 9 in


Catherine E. Creeger






January 2003