
“Sam is my second attempt at creating a realistic CG human head. My main reason for choosing to create an old man is that there are many more skin details on an older face than there are on a younger person. To me, that would mean “more for less” – by which I mean that because there are more details, it’s less of an effort to achieve realism.”
http://www.3dtotal.com/team/Tutorials_3/makingof_i_am_sam/sam_01.php