Throughout history, several cases of "feral children," deprived of human interaction in their early lives, have crept into scientific consciousness.

There was Victor, a boy found naked and filthy in France's wilderness in 1800. And Oxana Malaya, a Ukrainian girl raised by wild dogs, ate raw meat and ran on all fours. But the most famous case of all, happened in California — a girl nicknamed "Genie."

Beyond the horrors of growing up feral, worst of all, these kids may miss a critical period to learn language and never communicate like the rest of us.

Eric Lenneberg, a linguist and neurologist, first popularized the critical period (CP) hypothesis in the late 1960s. His research suggests that a specific window exists for learning language, either spoken or tactile. Outside of it, grasping the basics of communication becomes extremely difficult.

While debates still rage over how children acquire language, linguists agree that it's easiest during childhood, according to Wayne O'Neil, a linguistics professor at the Massachusetts Institute of Technology.

"Children have usually honed in on their native language's phonology by the end of the first year of life. The window re-opens from four to seven, and learning continues," he said. "If a child is isolated, then you've affected so many other things. You don't know what the hell is going on."

In 1997, Walter Cronkite narrated a PBS documentary telling Genie's tragic story. We've broken out the highlights.