In many eighteenth-century collections of human anatomy, one or more preparations of animals with cleft palate, a congenital defect still commonly known as harelip, can be found.
A quick exploration of the history of cleft palate tells us more about why these animal preparations were included in collections of human anatomy at a time when comparative anatomy was not a discipline yet. We probably all know or have seen somebody who has a corrected cleft lip, as the incidence is about one in 700 births nowadays, making it fairly common. (In comparison: the incidence for neural tube defects such as spina bifida is one in about 17,000 births, and for anencephaly –the absence of a large part of the brain and the skull- one in 10,000.)
Nowadays cleft palate can be treated successfully, but in the eighteenth century this was not at all the case. Most children born with a severe cleft palate died of malnourishment within weeks because of feeding problems. In less severe cases, sometimes an attempt was made to correct the cleft lip.
However, pre-anaesthetic, this was a rather cruel and potentially traumatizing procedure. The patient was held tight by an assistant, while the surgeon cut open and subsequently stitched together the two halves of the lip with thin needles. The needles then remained in the lip and were taken out one by one over the course of days or even weeks.
Even if the operation was successful, a child with a corrected cleft lip faced a lifelong stigma. Now known to be caused genetic or environmental factors, or a by a combination of both, in the eighteenth century cleft palate was still commonly explained by the theory of maternal imagination. This meant that people believed that birth defects were impressed on the foetus during pregnancy because the mother had seen, imagined, or done something. In the case of cleft palate, explanation varied from the mother having unchaste thoughts to her having had intercourse with the devil. After all, in classic iconography as well as popular believe, the hare represents lust, probably because of its speed of reproduction, and sometimes the devil itself. No wonder many sufferers of cleft palate find the term ‘harelip’ offensive!
Many eighteenth-century anatomists and physicians already realized that it was unlikely that the maternal imagination, or morals for that matter, could influence the foetus. After all, deformations like cleft palate also occurred in animals, which have neither imagination nor reason. To make their point, these men started to collect animals with birth defects that were also found in humans, and they recorded case histories to prove the maternal imagination was a fantasy. For example, Dutch anatomists Eduard Sandifort wrote of a new born girl with a severe cleft palate that she was her parents’ eleventh child, the first with such a defect, and that they were good Christians. However, the idea of the maternal imagination influencing the foetus was hard to eradicate: even in 1889, the authors of an encyclopaedia of children’s diseases still felt it was necessary to note that
“Pre-natal maternal impressions are often claimed as the cause of these marks [birth marks], and many cases are cited which lend a considerable degree of plausibility to the claim. It is more rational, however, to explain these cases by the principle of coincidence.”
 A. Nuck, Operationes Et Experimenta Chirurgica (Leiden: Samuel Luchtmans, 1733), p. 73-77.
 M. Hagner, ‘Enlightened Monsters’, in William Clark, Jan Golinski and Simon Schaffer (eds.) The Sciences in Enlightened Europe (Chicago & London: The University of Chicago Press, 1999), pp. 175-217.
 E. Sandifort, Observationes Anatomico-Pathologicae 2 vols. (Leiden: P. v.d. Eyk et D. Vygh, 1777-1781), vol. II, liber IV, caput III, 29- 38.
 Cyclopaedia of the diseases of children, medical and surgical. The articles written especially for the work by American, British, and Canadian authors. John M. Keating (ed.), (Philadelphia: J. B. Lippincott company, 1889), p.104.