It’s not very often that one can claim to have to chatted with with a living embodiment of history – - unless you’re Snoop Dogg or Talib Kweli, of course. So when the opportunity emerges, you have to reach out, grab it firmly (yet gently), and pull it close to bosom. This Tuesday you can encounter living, breathing history at the Bell House, where Donald Johansen, discovery of world-changing Lucy skeleton, will lecture about human evolution. On the agenda: