The Fantastical World of Hormones with Professor John Wass

By Isabelle Ferenczi

In this documentary, Professor John Wass, Professor of Endocrinology at Oxford University, highlights the importance of key hormones and the stories behind their discoveries. Hormones, a term coined by Ernest Starling from the Greek “haumea”, meaning “to excite”, is a fitting name for molecules which act on target cells resulting in a specific function. To date, more than 80 hormones of varying types, such as amines, peptides and steroids, have been discovered in humans. Professor Wass places prominence on testosterone, thyroid hormones, adrenalin and oestrogen. Moreover, the role of the pituitary gland, pancreas and fat cells in maintaining hormone levels is revealed. The greatly accomplished Professor Wass is a fantastic orator and has delivered a memorable and educational documentary. 

A noteworthy story outlined within the documentary is that of Farinelli, a celebrated male soprano singer of the 18th century, who maintained his pre-pubescent voice and hence could sing notes in the tenor and soprano ranges even as an adult. This was possible as Farinelli had been castrated. Castration, the removal of testicles, continued until the 20th century and affected multiple secondary sexual characteristics in addition to vocal pitch. For example, Farinelli had a straight hairline, rather than a  V-shaped one which is more common in adult males. Moreover, he had no Adam’s apple and long limbs. This showed that removing the testicles, where testosterone is produced in males, can have significant consequences on different parts of the body due to the lack of the aforementioned hormone. 

Moreover, in the 19th Century, Arnold Berthold experimented on capons. Capons are birds who have been castrated to render their meat more tender and cause the animal to become more docile. Upon the transplantation of testes into the abdomens of the capons, Berthold found that sexual behaviour and pre-castration characteristics returned. Furthermore, the testes redeveloped their blood supply. From these discoveries, it was theorised that the testes were the source of eternal youth. Indeed, Charles Edward Brown, a physiologist, claimed to have more strength, stamina and concentration following a blood and semen injection, although this is likely to have been a placebo effect. Unfortunately, while the testes and testosterone were celebrated, ovaries were not. It was surprising to discover that in the past, ovaries were thought to be the source of mental and physical disabilities, hence their removal was thought to cure hysteria, anorexia, anxiety and nymphomania.

The hour-long documentary also discussed the importance of appropriate regulation of hormone levels. The pituitary gland is key in this, as was shown by the extreme height of Charles Byrne, a man who lived in the 1780s. From his skeleton, it was discovered that he had a larger pituitary fossa, which revealed a tumour on his pituitary gland. In healthy individuals, the pituitary gland responds to hypothalamic regulation, which ensures that growth hormone levels remain at physiologically desirable levels. However, as a consequence of Mr Byrne’s tumour, extremely high levels of growth hormone were released.                      

Likewise, the pancreas is incredibly important in hormone regulation. Its removal from dogs resulted in a decrease in the production of digestive juices and insulin, showing that it is essential in hormone regulation. In 1921, Frederick Banting discovered insulin, the hormone controlling sugar levels, and was awarded the first Nobel prize in endocrinology. Prior to this discovery, diabetes mellitus sufferers never survived past their teens.  That was until the diabetic patient Leonard Thompson underwent Banting’s treatment, which consisted of an insulin injection using insulin produced by a dog’s pancreas, and in doing so, successfully treated his diabetes. Now, insulin is synthetically produced. 

More recently, the role of fat cells in regulating hormone levels has been revealed. The hormone  leptin is constantly being produced by fat cells and circulates in the bloodstream before acting on the brain. Its function is to act as an appetite inhibitor by  signalling to the brain that a sufficient amount of food has been consumed. Thus, the more leptin circulates in the blood, the less of an appetite one has. Dr Sadaf Farooqi, a Wellcome Trust Senior Research fellow in Clinical Science, found that mutations in the leptin processing pathway can cause obesity. For example, obesity can result from a reduced sensitivity to leptin, therefore injections of the hormone can be used as a treatment. 

This compelling documentary is a great starting point to gain an elementary understanding of the importance of hormones. While not offering in-depth explanations on the mechanisms of hormonal signalling, the documentary explains the basics and significance of hormones with  specific examples, their discoveries throughout history, and their potential uses in the future. 


Wass, J., 2021. The Fantastical World Of Hormones With Dr John Wass. [Documentary] TVF International. Available at: <; [Accessed 5 May 2021].

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