David J. Chivers & Holger Preuschoft 
Hands of Primates [PDF ebook] 

The hand commonly is considered to have exerted great influence on the evolution of typically human characteristics, like upright posture, stereoscopic vision, manipulative handling of parts of the environment. The German term Begreifen , which is commonly used for the understanding of complex relationships in a generalised, abstract sense, always implies the original meaning of seizing objects with the aid of the hands. The hands are also of greatest importance for the survival of the other, non-human primates. Hands are absolutely essential for locomotion in an arboreal habitat, and the intake of food is dependant on the use of the hands as well: primates very rarely take in food directly with their mouths, in the wast majority of cases they seize food items with their hands. Even drinking is often performed by dipping the hand into the water and licking the drops from hand and forearm. An organ of such importance will very probably be adapted to its function . This statement is made so often, that any further considerations seem superfluous. Nobody doubts, that the hands of primates are highly adaptive organs, the general form and internal structure of which are closely related to the necessities of life. However, if one tries to go beyond this general statement, he finds himself confront- ed with several problems: First of all, a point which W. GUTMANN has emphasized repeatedly: according to the results obtained by genetics, the first thing to appear is the mutated character.