“O Cuckoo! shall I call thee Bird,/Or but a wandering Voice?” William Wordsworth

Above: James Gillray’s 1802 caricature of Jenner vaccinating patients (verb from vacca, Latin for cow, because of early use of cowpox virus against smallpox).

I am staying in Alveston, South Gloucestershire, which lies in the Vale of Berkeley, between the River Severn and the Cotswold Edge, north of Bristol and south of Gloucester. Alveston is one of the villages surrounding the towns of Thornbury (my ultimate destination), Cam, Dursley, Wotton under Edge, and, seven miles away, Berkeley.

Berkeley was the birthplace in 1749 of Edward Jenner, son of the local vicar. He came to be known as “the father of immunology”, and in 1821 was appointed physician extraordinary to King George IV. Berkeley was his home town when he died, early in 1823.

(The website for the Baylor University Medical Center carries a paper by Stefan Riedel entitled “Edward Jenner and the history of smallpox and vaccination”.)

From the age of fourteen, Edward was apprenticed to Daniel Ludlow, an eminent surgeon, in Chipping Sodbury. In 1770, he became apprenticed in surgery and anatomy as house pupil under surgeon John Hunter and others at St George’s Hospital, London. Hunter gave Jenner William Harvey’s advice, well known in medical circles and characteristic of the Age of Enlightenment: “Don’t think; try.”.

In 1772, Edward returned to Berkeley, spending most of the rest of his career as a doctor in his native town. With others, he formed the Fleece Medical Society, meeting in the parlour of the Fleece Inn, Rodborough, to dine together and read papers on medical subjects. Edward belonged to a similar society which met in Alveston.

Edward was elected Fellow of the Royal Society in 1788, following his publication of a careful study (in England during 1786-7) of the previously misunderstood life of the nested cuckoo (Cuculus canorus). He explained how the newly hatched cuckoo pushed its host’s eggs and fledgling chicks out of the nest – contrary to existing belief that the adult cuckoo did it. Having observed this behaviour, Jenner demonstrated an anatomical adaptation for it: the baby cuckoo has a depression in its back, not present after twelve days of life, that enables it to cup eggs and other chicks. The adult does not remain long enough in the area to perform this task.

An article published as late as 1892 claimed that the “absurdity” of Jenner’s account had been demonstrated in 1836 by the naturalist Charles Waterton. A few years earlier Charles Creighton (1847-1927), the epidemiologist and medical historian, whose intense opposition to vaccination led him to denigrate Jenner in every conceivable way, had described his paper on the cuckoo as mainly “a tissue of inconsistencies and absurdities”.

Jenner’s understanding of the cuckoo’s behaviour was not entirely believed until the artist Jemima Blackburn (1823-1909), a keen observer of bird life, saw a blind nestling pushing out a host’s egg. Her description and illustration of this, originally in a popular narrative for children called “The Pipits” (1871), were enough to convince Charles Darwin to revise the examples of innate behaviour in the 6th edition of “On the Origin of Species”.

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