...exactly what late night websurfing will get you.

apoptosis = "the process of programmed cell death (PCD) that may occur in multicellular organisms.
Programmed cell death is an integral part of both plant and animal tissue development. Development of an organ or tissue is often preceded by the extensive division and differentiation of a particular cell, the resultant mass is then "pruned" into the correct form by apoptosis."
Thus, "Incomplete differentiation in two toes (syndactyly) [is] due to lack of apoptosis."
Thanks Wikipedia, for helping to solve one of life's little mysteries.
And I suppose the biological realm isn't so completely lost on me as I had thought...