Human memory is a famously tricky thing. We remember some things. We forget a lot more. And we shape and sculpt the memories we do have with a vengeance. But more and more, the actual events of our lives are being recorded electronically. In Facebook albums and Twitter posts and smartphone files, yes, but also in thousands of digital transactions we don't even think about. Now, two top Microsoft computer scientists are talking about an era of e-memory — "total recall" — as a revolution in what it means to be human. This hour, On Point: E-memory, total recall, and human nature.