This 5mn video is an attempt by Anthony Cerniello at showing the aging process of a person in a timelapse manner. I’d recommend watching the video before reading anything about how it was done.
Here comes the spoiler: according to this article, it was created from photos of the subject and her family relatives who shared most face similarities. The photos were then animated and morphed together. Like the article points out, the animation still falls within the uncanny valley, but pause at any time and all you see is an real face.