As long as they aren’t fast zombies, humanity should be okay. Max Brooks, author of World War Z , sat down New York Comic-Con to discuss what makes the undead tick.
Chain swarms, or zombie herds, are accidental.
When a zombie sees a human, it emits a moan. According to Max Brook's this is not a signal to other zombies in the area, but just an instinctual reaction to seeing a target to infect. However! If there are more undead in the area, they will here the moan and come towards the area, themselves moaning the whole way. So while not a "dinner bell" the behavior can still draw dozens, hundreds, or even thousands of zombies to one area.
madame-of-nightmares.tumblr.com
Zombies do not think humans are delicious snacks.
Brooks uses zombies as a virus transference. They want to bite you to spread the infection, not to taste the sweet, sweet flesh of human one more time.
The living dead still have use of all their senses.
But they use them all equally. As apex predators, Brooks' told us, humanity pulls most of our information from sight even though all our other senses are constantly inputting data too. So while the zombies might not have 20/20 vision, they can hear that tin can hit the floor or smell the spices from that dry Ramen packet you ate six hours ago.
The undead do decompose, just at varying rates.
Since they aren't eating human flesh for survival, the undead are still decomposing. Brooks' told us people in the tropics would have the shortest half-life before their undead stop being dangerous but with the freeze and thaw cycle in the temperate zone, zombies could survive for years as the winter preserved their bodies.