When does a hobby become a scientific subject ?
Thanks to Darwin’s correspondence, we can get an insight into what Darwin called “an uncommonly curious subject” and his very own “hobby-horse”.
The “uncommonly curious subject” was the expression of emotions in animals and humans; Darwin spent almost forty years thinking, taking notes and inquiring about it, gathering observations and anecdotes from the most remote places on earth as well as from his own domestic surroundings.
As early as the 1830s, Charles Darwin had begun to record and make observations on expressions, noting the behaviour of animals as well as humans. In another example of Victorian women involved in scientific observations and experiments, the soon-to-be-married Emma was also contributing to the project; months later, Darwin began recording the expressions and behaviour of his own children, starting with his “little animalcule of a son, William Erasmus by name”.
Over the following years, Darwin’s interest did not vanish, but he was being cautious about his research. In January 1860, he wrote to Charles Lyell: “On that subject I have collected a good many facts & speculated: but I do not suppose I shall ever publish”, although he had, only a few days earlier, proved his continuous interest by sending a first formal query about Fuegians and Patagonians to the missionary Thomas Bridges. In 1862, he informed the botanist Joseph Dalton Hooker that: “Expression is one of my hobby-horses; I have got some funny notions on subject” ; a few years later, Darwin had resolved to send other circulars with questions similar to the 1862 questionnaire and was writing more confidently to William Bowman: “Expression in animals & men is at present a hobby of mine & I think I shall probably utilize my notes made during several years.”
In 1872, thirteen years after the Origin and Species and one year after the Descent of Man, Charles Darwin eventually published his work on the Expression of the Emotions in Man and Animals. It was an immediate best-seller, although the first edition was not exhausted during Darwin’s lifetime. It remains, with the correspondence pertaining to it and as expressed by Paul Ekman in the introduction to the third edition of The Expression of the Emotions in Man and Animals “a most fascinating example of “Darwin’s attempts to obtain more systematic evidence on the question of universality”.