Has anyone noticed that all wild animals, all mammals, except the elephant, has erect ears? Nature must have felt that one of the basics of survival was good hearing. It follows that the hanging or drop ear must be man-made due to domestication process (1), and that man found, as time went on, that in certain cases the prick, or upright ear, served him better, so he trimmed them.
In times of war the cropping of dogs ears not only saved the lives of dogs in preventing infections and injuries, but the lives of their handlers as well. Out of thirty dog breeds tested for the US Marines two were chosen to be Dogs of War, the Doberman (cropped) and the German shepherd, both having upright ears.
"The dogs exercised exceptional HEARing, up to 35,000 hertz per second with ability to CLOSE-OFF their INNER EAR and micro-focus on a particular sound. "(2)
Nothing has changed since the times of war. The same Animal Husbandry practices used in history that promoted health and function would also stand true for today.
Ear cropping is not cruel when performed by a licensed Professional, decision or choice should remain between breeders and owners in proper consultation with their veterinarian.
(1) Dmitry_Konstantinovich_Belyaev - Belyaev’s fox experiment http://en.wikipedia.org/wiki/Dmitry_Konstantinovich_Belyaev#Belyaev.E2.80.99s_fox_experiment
(2) Paul Garson - Man’s Best Friend on the WWII Battlefield http://writingdisorder.com/paul-garson/