Jerome Bixby's The Man From Earth - 8.5/10
Streaming on Netflix right now.
John (David Lee Smith), a college professor, is leaving his university after 10 years. A group of colleagues come to his cabin to say goodbye. Early on, comments are made about how little he has changed in appearance over the past 10 years. "He hasn't aged a day." John basically claims to be an immortal 14,000 year old caveman. For the rest of the movie he's questioned by his colleagues (a biologist, anthropologist, psychologist, Christian literalist) about his life. The questions are deep and the dialog is engaging throughout.
The acting is not good, but the script more than makes up for it. It's one of the most interesting movies I've seen in a long time. A hidden gem if you ask me.