Glenn Harlan Reynolds
Originally posted November 20, 2017
Here is an excerpt:
Hunters and gatherers were at far less risk for infectious disease because they didn’t encounter very many new people very often. Their exposure was low, and contact among such bands was sporadic enough that diseases couldn’t spread very fast.
It wasn’t until you crowded thousands, or tens of thousands of them, along with their animals, into small dense areas with poor sanitation that disease outbreaks took off. Instead of meeting dozens of new people per year, an urban dweller probably encountered hundreds per day. Diseases that would have affected only a few people at a time as they spread slowly across a continent (or just burned out for lack of new carriers) would now leap from person to person in a flash.
Likewise, in recent years we’ve gone from an era when ideas spread comparatively slowly, to one in which social media in particular allow them to spread like wildfire. Sometimes that’s good, when they’re good ideas. But most ideas are probably bad; certainly 90% of ideas aren’t in the top 10%. Maybe we don’t know the mental disease vectors that we’re inadvertently unleashing.
It took three things to help control the spread of disease in cities: sanitation, acclimation and better nutrition. In early cities, after all, people had no idea how diseases spread, something we didn’t fully understand until the late 19th century. But rule-of-thumb sanitation made things a lot better over time. Also, populations eventually adapted: Diseases became endemic, not epidemic, and usually less severe as people developed immunity. And finally, as Scott notes, surviving disease was always a function of nutrition, with better-nourished populations doing much better than malnourished ones.
The article is here.