In the first half of the 19th century, teratology became a science free from considerations of God’s direct interference in natural processes. It also limited its area of study to birth defects, therefore eliminating imaginary monsters.

Anatomists approached the question of monstrosity as a whole and confirmed that it was a part of the evolution of the foetus. They depicted ‘monstrosity’ as part of a natural process, rather than as an independently produced phenomenon. Furthermore, they established a distinction between physical anomaly and monstrosity, and created a specific vocabulary for each of them. It is interesting to note that modern teratologists retained ‘monster’ as a scientific term, therefore using a word which, through centuries, had inspired many prejudices.

The early nineteenth century also witnessed the first attempts by men to artificially create monstrous deformity in living organisms as a way to better understand the mechanisms that led to monstrosity.



Johann Friedrich Meckel (1781-1833). De duplicitate monstrosa commentarius… Halle & Berlin: E Librariis Orphanotrophei, 1815.

Meckel, a pathologist and comparative anatomist who was a predecessor of Darwin, contributed to the creation of scientific teratology by promoting the view that the higher animals were the result of a progressive evolution from lower forms of life.

Etienne Geoffroy Saint-Hilaire (1772-1844). Philosophie anatomique. Des Monstruosités humaines, ouvrage contenant une classification des monstres …Paris: auteur, 1822.

The works of the Geoffroy St. Hilaire family were fundamental in the development of teratology. Etienne, the father, demonstrated through comparative anatomical studies that a cause of monstrosity was an interruption in the development of the foetus. This brought to an end lingering support for the theory that a pregnant woman’s imagination could influence the development of monstrosities.

Rejecting previous classifications which were limited to a description of different monsters, Geoffroy de St. Hilaire elaborated a new classification system emphasizing the character of monstrosity rather than the individual monster.

Isidore Geoffroy Saint-Hilaire (1805-1861). Histoire générale et particulière des anomalies de l’organisation chez l’homme et les animaux … Atlas contenant 20 planches avec leur explication …Paris: J.B. Baillière, 1857.



Isidore Geoffroy St-Hilaire continued the research of his father Etienne. He established a classification system more elaborate than that of his father, which had limited monstrosity to extreme anomalies. Furthermore, Isidore refused to view physically unusual individuals as failed ‘normal’ beings to be rejected by society.


Camille Dareste (1822-1899). Recherches sur la production artificielle des monstruosités ou essais de tératogenie expérimentale…Paris: Reinuald, 1891.

Dareste founded experimental teratology and, for the first time, artificially produced birth defects and monstrous births. He experimented with chicken embryos and succeeded in creating a form of monstrosity unknown before. Through such experiments, Dareste sought a better understanding of monstrosity.

Mary Wollstonecraft Shelley (1797-1851). Frankenstein; or, The Modern Prometheus ... London: Collier Macmillan Publishers, 1961.

Frankenstein was first published in 1818. Its author, Mary Shelley, was well aware of the medical and other scientific discoveries of her time, and used them in her novel. Far from describing a ‘freak’, Shelley described a monster fabricated by science, and in doing so anticipated the more benign monsters such as those produced by teratologists later.

Frankenstein has retained its popularity because it succeeded in expressing feelings that have persisted, such as fear of experimental science and misunderstanding of monsters.

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