London in the time of cholera

I’ve just read The Ghost Map by Steven Johnson. This extraordinary book, which nominally chronicles the campaign of physician Dr John Snow to persuade Victorian England that cholera was caused by contaminated water rather than noxious odours, also takes the reader on long and fascinating asides into topics like how living at density selected for alcohol-tolerant genes.

Deaths from cholera, Victorian London

As this article points out, large cities in all parts of the world used to be very dangerous places where the very proximity of humans directly led to disease and death.

I already knew the basics of John Snow’s battle with the established order and his famous map of Broad Street from TV programs and the odd book, like Mathew Kneale’s excellent novel about a Victorian hydraulic engineer, Sweet Thames.

But the particular value of Stevenson’s take on London’s cholera epidemic is the attention it gives to the broader circumstances of the times and the way he burrows deeply into the underlying social, medical and technological issues.

He talks, for example, about how humans living at close quarters historically addressed their vulnerability to polluted water by drinking alcohol instead (notwithstanding it is itself poisonous and addictive). Nothing new about that perhaps, but what is interesting is how the desire to live at higher density gradually selected for genes that could tolerate alcohol: Read the rest of this entry »