Ravens mate for life. The couple establishes its territory and chases away intruders. But, here is where it gets interesting. If an intruder finds a large supply of food it will call out. This sounds pretty stupid at first because it immediately draws the “owners” of the territory to the food. They come and chase the caller away, but the call also draws other ravens. Soon, there are too many intruders to be fended off and all the interlopers get a full meal.
I believe the Campion Virus may exhibit similar behavior. If we believe that the Campion virus, or older parts of the virus have been around forever and not something cooked up in a lab, the calling (Moaning) behavior may have co-evolved with the cavemen. Going back a few thousand years the number of humans was smaller and population density was much lower. The moaning behavior exhibited by zombies will draw others of its kind to the area for “food” and additional victims. If a single zombie is “killed”, reinforcements will soon arrive to get the job done. More zombies are created the process continues. So, zombies do not really interact much at all. But, the virus has used traditional evolutionary methods to become the horror it is today.
Food <=> Zombie (silent)
Food <=> Zombie (moan) <= Zombie (moan) <= Zombie (moan) ...
The chain depicted should actually be envisioned in a 360degree cirlce around EACH zombie, not just the "Food"