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Article: Our thumbs.
- Article from:
- Baylor University Medical Center Proceedings
- Article date:
- October 1, 2002
- Author:
CopyrightCOPYRIGHT 2002 The Baylor University Medical Center. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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The hand without a thumb is at worst nothing but an animated spatula * and at best a pair of forceps whose points don't meet properly.--John Napier (1)
ORIGINS
Our earliest known ancestor is the fish Rhipidistia (2), which has been extinct for 230 million years. Its pectoral fin is the precursor of our hand, which has 4 fingers, each with 3 phalanges, and a thumb with only 2 phalanges.
It is known that almost without exception, the first ray of mammals, reptiles and amphibians, and humans had 2 phalanges. Galen (AD 165) thought the bones of the thumb were really 3 phalanges and that it lacked a metacarpal. Vesalius in 1543 agreed, saying that ...