Darwin's Shoulder Bag

Yesterday I witnessed a young man, walking a few paces in front of me, allow his shoulder bag to slip from his shoulder and crash to the pavement. This vision prompted a few idle thoughts. First, that young men (and older) now carry bags; just a few years ago, a bag was considered too effeminate an accessory for the male of the species. Only briefcases or other work-related reticules were acceptable.  Men now have stuff to carry around, too, and are not afraid to admit it, in the form of a sometimes rather trendy bag.  
Secondly, that over the decades (or perhaps centuries) women have evolved techniques of hanging onto their bags, be they shoulder bags, handbags, satchels, clutches or totes, despite their inferior upper body strength, and despite these methods sometimes involving actual body malfunction (along the lines of tennis elbow or repetitive strain disorder). 
Thirdly, evolution seems again to have missed a trick. I'm sure that some sort of bag-friendly anatomical element would have given added value to homo sapiens.