RT Journal
A1 Ladd, Amy L.
T1 Upper-Limb Evolution and Development: Skeletons in the ClosetCongenital Anomalies and Evolution's Template
JF The Journal of Bone & Joint Surgery
JO The Journal of Bone & Joint Surgery
YR 2009
FD July 1
VO 91
IS Supplement_4
SP 19
OP 25
DO 10.2106/JBJS.I.00284
UL http://dx.doi.org/10.2106/JBJS.I.00284
AB 
The human hand evolved from a specialized fin some 400 million years ago, and its many shapes and purposes have culminated in a masterful instrument capable of great skill—and a source of great despair. When things go awry in development, aberrancies range from the appearance of simple webbing and skin tags to the disappearance of the radius and mirror hand duplication. As surprising and rare as these conditions are, they occur in patterns of morphologic consistencies, although the inciting genetic programming and signaling pathways are complex, interrelated, and only provisionally understood. Identifying the gene's role in evolution has hallmarked much of evolutionary study in the twentieth century, with the discovery of genetic aberrations associated with anomalies often providing a clue to the normal orchestration and development of the limb bud.