To the contemporary eye, De monstrorum causis features what we now know are fabled characters like wolf children and centaurs. But he also included abnormalities he witnessed firsthand in his medical practice, frequently drawing conjoined twins and intersex individuals. Despite the fact that the scientist grouped people with congenital disabilities with “monsters,” he was still progressive for his time. As his peers shunned people who looked like his subjects—some believed anatomical abnormalities resulted from sin—Liceti believed they were just the result of nature, both powerful and inventive.
Perhaps a symptom of his era’s mystification about reproduction, the genitalia in Liceti’s work ranges from the expected to the otherworldly. One “monster” sports what looks like a frontally-attached tail, nearly as long as its legs. Another creature with a bald, egg-shaped head appears to have vaginal folds taking up nearly half its stomach. Liceti posited that a narrow uterus or complications with a mother’s placenta could generate some of the birth defects he observed (now referred to as “congenital disabilities”). Some scholars even credit him as the father of teratology, or the study of congenital disabilities.