THE GRAMMAR OF HAPPINESS, a one-hour special premiering Sunday, May 12 at 9 p.m. ET/PT on Smithsonian Channel, traces the epic story of Everett’s journey and the profound effect it had on him personally and professionally. He lost his faith and his family, but gained an insight that overturns decades of conventional wisdom. It has also pushed him into conflict with perhaps the world’s most esteemed academic, Noam Chomsky.

In the world of linguistics, Everett’s argument is akin to saying that Einstein got it wrong on relativity. He makes the case in his new book, “Language: A Cultural Tool,” which The New York Times called “full of intellectually omnivorous insights” and “that rare thing: a warm linguistics book.”

Convinced by the Pirahã’s steadfast beliefs that life should be lived in the present, that the past is behind us and thus irrelevant and that spiritual claims must be proven to be correct, Everett threw off the religious cloth to become a crusading and controversial academic. He re-invented himself as a linguist, grabbing headlines by challenging Chomsky’s theory of universal grammar – the idea that there’s a genetic foundation for all human language. In THE GRAMMAR OF HAPPINESS scientists from MIT design a computer analysis program to test Everett’s theory in hopes of proving once and for all who is right: the legend or the maverick.

Everett’s most controversial claim is that the Pirahã language lacks “recursion” – the ability to build an infinite number of sentences within sentences, regarded by Chomsky-ists as perhaps the most fundamental characteristic of human language. It is our ability to use recursion, or so the orthodoxy goes, that sets human language aside from animal communication.

Today, Dr. Everett is the dean of Arts and Sciences at Bentley University in Massachusetts. Meanwhile, oblivious to the academic arguments raging around their language, the Pirahã continue to live in the moment, deep in the Brazilian Amazon, with few concessions to modern life. They call themselves “the Straight Ones,” while outsiders are considered to have “Crooked Heads.”

As Everett’s longtime teacher, Kohai, puts it in the THE GRAMMAR OF HAPPINESS: “Dan came here. He wanted to learn Pirahã.  He wanted to have a ‘straight head.” Or as another put it in the film: “We love Dan. Dan speaks our language.”