Complex sentence: It is a long held belief that it takes more muscles to frown than it does to smile, however according to Dr. David H. Song of the Univeristy of Chicago Medical Center frowning requires 11 muscles while smiling requires 12.
Split into simpler sentences: It is a long-held belief that it takes more muscles to frown than it does to smile. According to Dr. David H. Song of the Univeristy of Chicago Medical Center, however, frowning requires 11 muscles while smiling requires 12.