A kiss without a moustache, the proverb says, is like an egg without salt and, added Jean Paul Sartre, like good without evil. The proverb doesn’t make clear which kisser should have the moustache and who loses out, but we can perhaps assume that the man has the moustache and the woman suffers a saltless kiss. But an experiment I’ve just read about should provide consolation to all women missing out on moustachioed kisses.

The experiment is described in Survival of the Prettiest: the Science of Beauty by Nancy Etcoff, a wonderful book that has already prompted me to write one blog. It took place in 1907 in Paris and was probably prompted by contemporary debate over the safety of beards and moustaches. As every admirer of paintings, particularly those by Henri Fantin-Latour knows, beards and moustaches were the norm in the 19th century. But then Pasteur developed the germ theory, and people began to wonder what lurked in all that hair.

So an unnamed scientist walked through the streets of Paris, which must in 1907 have been full of horse shit and other filth, with two men, one with a moustache and one without. We are not told about the size and nature of the moustache, but I imagine it to be bushy. Nor are we told how the subjects were selected.

After the walk the two men each kissed a woman “whose lips had been sterilised.” It’s not clear whether they kissed the same woman or two different ones and if the same one in which order; and my dim memory of bacteriology makes me sceptical about the possibility of sterilising lips. Was the woman (or the women) autoclaved? I hope that she (or they) gave fully informed consent. After the kisses the “residue was wiped off and dipped in a sterile solution and left standing for four days.”

After four days the residue from the man without a moustache contained only “harmless yeast” while that from the moustachioed man was “swarming with malignant microbes—diphtheria, putrefactive germs, minute bits of food, a hair from a spider’s legs and other odds and ends.” The reporting seems less than neutral.

It’s doubtful that this case study would make it into Science or Nature or even BMJ Case Reports. Detail is lacking, even the name of “the scientist.” There is no conflict of interest statement, but I suspect that the Parisian chamber of barbers may have funded the study.

But who cares whether this study ever took place? I find the whole idea scientifically, artistically, geographically, and erotically exciting. We should repeat the study, perhaps in a series of the world’s most beautiful cities.

Richard Smith was the editor of the BMJ until 2004 and is director of the United Health Group’s chronic disease initiative.