In 1974 James Herbert published a rather nifty piece of fiction wherein rats, after millions of years of survival under the heel of humanity, relegated to living only at the whim of man, rise and begin to systematically attack and prey on us.
He followed it with The Lair in 1979. In this one the rats are sorting into caste systems and are licking their collective chops remembering the glory days of running amok and feeding on man.
1984 saw the release of Domain. This one is an end of the world story. Man wages the final war and while they are distracted rats emerge for the sewers and wreak havoc.
He rounded out the saga with The City. A graphic novel that tells the story of man's defeat. They are now scavenging in the ruins the rats are now the ones that allow man's existence to continue.
Now, while James Herbert was writing this terrifying series of books about how rats begin to get more aggressive and unafraid of man, a scientist deep in Siberia was conducting research about how our ancestors may have domesticated animals. He uses rats in these experiments. Apparently he separates the rats into two groups: one sweet and snuggly and the other evil and demented. According to the article the nice group, upon seeing people, walk to the bars of their cage and push their nose through and enjoy a good pat on the nose and scratch under the chin. The evil group, called 'hyper-aggressive' hurl themselves at the bars shrieking, wanting to escape to tear you limb from limb.
Some interesting quotes from said article:
“Imagine the most evil supervillain and the nicest, sweetest cartoon
animal, and that’s what these two strains of rat are like,” said
Tecumseh Fitch, an animal behavior expert at the University of St.
Andrews in Scotland.
When the aggressive rats have to be moved, Mr. Albert places two cages
side by side with the doors open and lets the rats change cages by
themselves. He is taking care that they do not escape to the sewers of
Leipzig, he said.
Yes that's right. He specifily mentioned the care he was taking so as to keep the rats out of sewers. This leads me to wonder if he has indeed read the books by James Herbert. I'll wager he has.
The full article can found at this link: Nice Rats, Nasty Rats: Maybe It’s All in the Genes