In early human fetal development, webbing (syndactyly) of the toes and fingers is normal.

At about 6 weeks of gestation, apoptosis takes place due to a protein named sonic hedgehog, also known as SHH, which dissolves the tissue between the fingers and toes, and the webbing disappears.

In some fetuses, this process does not occur completely between all fingers or toes and some residual webbing remains.

Special situations, such as complex syndactyly and involvement of border digits, may warrant surgical intervention earlier than 6 months.

Skin can also be used from the back of the hand by mobilizing it (called a "graftless" syndactyly correction), which requires planning over a period of months prior to surgery.

The earliest appreciation of syndactyly as a birth anomaly or burn-trauma can be traced back to the Andalusian Muslim surgeon Al-Zahrawi (d. 1013 CE), known in the West as Abulcasis.