ABSTRACT
The occurrence of birth defects has been noted since the earliest human records, but the factors that predispose or initiate abnormal embryonic development are not well understood. The early Babylonians thought that defective infants were messages from the gods, while the ancient Greeks connected congenital malformations with mythological figures. Some cultures attributed monstrous offspring to the interbreeding of humans and animals. A popular view in Europe during the Middle Ages was that congenital anomalies resulted from cohabitation of humans with witches and demons. Emergence of scientific inquiry in the sixteenth and seventeenth centuries led to the idea that birth defects were due to interruptions in developmental processes, narrowness of the uterus, faulty maternal posture, or external physical violence. After Mendel's fundamental principles of genetics were rediscovered in 1900, it was generally assumed that abnormal development was under genetic control, and purely genetic explanations were accepted for a variety of biological phenomena, including birth defects. The importance attributed to genetics resulted in little consideration of other factors that could influence development (Wilson, 1973a,b; Warkany, 1979).
