It’s ridiculously wrong though. Ketchup has tons of varieties, even if you only talk about tomato ketchup (which is not the only kind, although the vast majority). I can easily name more common varieties of tomato ketchup than of mustard. This seems kind of symptomatic of Gladwell’s writing, to be honest: fancy, convincing, but divorced from facts and true only in a limited, cherry-picked niche.

In the context of evolutionary anthropology this is known as “just-so” stories. Fitting then, that Gladwell’s ketchup essay also contains a just-so stories. He just couldn’t resist.