The Pirahã language does not have color words or grammatical devices for putting phrases inside other phrases. They do not have fiction or creation myths, and they have a lack of numbers and counting. Despite 200 years of contact, they have steadfastly refused to learn Portuguese or any other outside language. The unifying feature behind all of these characteristics is a cultural restriction against talking about things that extend beyond personal experience. This restriction counters claims of linguists, such as Noam Chomsky, that grammar is genetically driven system with universal features.
I find this truly stupendous.