How do the 6 friends photos at the top of Facebook Timeline get choosen?

[Banana.]

How do the 6 friends photos at the top of Facebook Timeline get choosen?
Why do certain friends seem to show up as one of the the six photos in the small friends list photo box at the top of Facebook Timeline? Are these the 6 friends people who have visited your profile recently or have been online recently? What is the reason for only seeing certain friends pictures in this friends box?

[Ajeet]

I think they are chosen randomly

[Lenny]

The 6 friends at the top of your friends are completely randomized by Facebook.

[Herman]

Photos uploaded to Facebook from your cell phone may end up in the "Mobile Uploads" album but they do not have to stay there. Over time and numerous photo uploads your "Mobile Uploads" album can become a hodgepodge of unrelated pictures. Organizing photos into associated Facebook albums may make it easier to search for a specific picture at a later date.