The hand and hominisation.

Morphological features of the hands of Varanus, Iguana, opossum and primates were disclosed by dissection and an attempt was made to a functional assessment of the findings. A simple functional morphological pattern seems to prevail in the reptiles studied. A specialised function of claw retraction could explain the complex digital morphology in opossum. Already in opossum functions cannot be defined sharply. Functional domains and functional options within these domains become the prevailing picture in primates. Hand morphology of the great apes and man warrants to distinguish one functional domain. In man a full-fledged thumb dominates the hand morphology next to other features, which could be functionally interpreted as a unique setting for perception of form. This could have been a primary drive in cerebral development and hominisation.