Poking, he gets. Friending, the verb, he invented. But Mark Zuckerberg is still a little unclear on the whole concept of a high five, as evidenced by the above photo from his visit to Harvard earlier this week.

The robotic Facebook CEO claims he is learning to better appreciate the human constructs of "girlfriend" and "pet dog." But there's is still plenty about socializing the social networking kingpin has yet to learn. Until he does, Zuckerberg is keeping all non computerized humans at bay. The vast majority of his time at Harvard was spent in spaces cordoned off for computer science students.

[Photo of Zuckerberg at Harvard by Rose Lincoln via Harvard Gazette]