As this new science of habit has emerged, controversies have erupted when the tactics have been used to sell questionable beauty creams or unhealthy foods.
Waves of drought in Cape Verde prompted massive emigration throughout the 20th century, to the point more CapeVerdeans now live outside the country than in it.
This happens in part because refined carbohydrates raise blood-sugar levels, setting up an insulin surge that drives blood sugar down again, causing rebound hunger.
In fact, both people who died in outbreaks related to unpasteurized milk between 1999 and 2008 died of infections caused by fresh Mexican-style cheese made from raw milk.
None of this means that what is popular is stagnant, but even dramatic shifts in opinion and political leanings follow a typical pendular pattern, reactively swinging back and forth.