A short but sweet one;

the pack of wild dogs analogy has been thrown around a bit as of late. And a thing to note about that is....even a wild dog that has had no interaction with human can be slowly coxed into caring for a human,to be loyal and to be trained....meanwhile, a wolf cannot be trained..something in The genetic makeup of the two is just different enough that they will show that difference, dogs can be lead....wolves cannot. Breeders have spent countless years trying to break wolves of this to no avail....

Now, think of that when comparing zombie "packs" to a pack of dogs....(Michaels words)