At the heart of this book is the matter of how and why animals evolved into particular shapes. The purpose of this book is to identify the physical laws which decide over the evolutionary (selective) value of body shape and morphological characters. Comparing the mechanical necessities with morphological details, Dr. Preuschoft attempts to understand how evolution works, and which sorts of limitations are set by selection.
The author tries to explain morphological traits in more biomechanical detail without getting lost in physics, or in methods. Most emphasis is placed on the proximate question, namely the identification of the mechanical stresses which must be sustained by the respective body parts, when they move the body or its parts against resistance. This monograph focuses on "primitive" animals in the first part of the book, with highly specialized mammals at the end. Through this book readers will learn more about living and fossil animals. Particular attention is given to human evolution. The aim of this section is not to produce another evolutionary tree, nor to refine a former one, but to contribute to answering the question: "WHY early humans have developed their particular body shape".