You may remember a video I posted three weeks ago of a diavlog between Razib Khan and John Hawks. You may also remember a happy coincidence -- about a week after that diavlog aired, the results of fifteen years of work on the "Ardi" fossil were published. So! here are John and Razib doing another diavlog in that light.
You really ought to listen to this one, even if your interest in paleoanthropology is not as high as mine. This is a gold standard for scientific discussions geared for the lay audience -- solid questions from a well-prepared Razib, and from John, a most clear portrayal of how science is actually done in the real world. Good stuff.
As always with Bloggingheads diavlogs, you have options besides streaming the above. Click the "alt. video link" if you'd rather download an audio or video file.