The Ghost Map is a book about:
- a bacterium
- the human body
- a geographical map
- a man
- a working friendship
- a household
- a city government
- a neighborhood
- a waste management system1
- an epidemic
- a city
- human civilization
You hooked yet? Well, you should be. As the narrative unfolds around the 1854 London cholera epidemic, author Steven Johnson weaves all of these social, geographical, and biological structures/webs/networks into a scientific parable for the contemporary world. The book is at its best when it zooms among these different scales in a Powers of Ten-like fashion (something Johnson calls The Long Zoom), demonstrating the interplay between them: the way the geography of a neighborhood affected the spread of a virus, how ideas spreading within a social context are like an epidemic, or the comparison between the organism of the city and the geography of a bacterial colony within the human colon. None of this is surprising if you've read anything about emergence, complexity, or social scale invariance, but Johnson effectively demonstrates how tightly coupled the development of (as well as our understanding of) viral epidemics and large cities were across all of these scales.
The other main theme I saw in the book is how inherently messy science is. Unlike many biographies, The Ghost Map doesn't try to tie everything up into a nice little package to make a better story. The cholera epidemic and its resolution was sloppy; there was no aha! moment where everyone involved understood what was going on and knew what had to be done. But the scientific method applied by John Snow to the situation was solid and as more evidence became available over the years, his theory of and solution to cholera epidemics were revealed as actual fact. Johnson reminds us that that's how science works most of the time; science is a process, not a set of facts and theories. During the recent debate in the US over evolution and intelligent design, I felt a reluctance on the part of scientists to admit to this messiness because it would give an opening to their detractors: "haha, so you admit you don't know what's going on at all!" Which is unfortunate, because science is powerful in its nuance and rough edges (in some ways, science is what happens at the margins) in helping us understand ourselves and the world we live in.
[1] Had Mark Kurlansky written this book, it would have been called "Shit: How Human Effluence Changed the World". ↩