Nice Rats, Nasty Rats: Maybe It’s All in the Genes
nytimes.com
On an animal-breeding farm in Siberia are cages housing two colonies of rats. In one colony, the rats have been bred for tameness in the hope of mimicking the mysterious process by which Neolithic farmers first domesticated an animal still kept today. When a visitor enters the room where the tame rats are kept, they poke their snouts through the bars to be petted.
The other colony of rats has been bred from exactly the same stock, but for aggressiveness instead. These animals are ferocious. When a visitor appears, the rats hurl themselves screaming toward their bars.
“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 who several years ago visited the rats at the farm, about six miles from Akademgorodok, near the Siberian city of Novosibirsk. Frank Albert, a graduate student at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, is working with both the tame and the hyperaggressive Siberian strains in the hope of understanding the genetic basis of their behavioral differences.
“The ferocious rats cannot be handled,” Mr. Albert said. “They will not tolerate it. They go totally crazy if you try to pick them up.”
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.
The two strains of rat are part of a remarkable experiment started in the former Soviet Union in 1959 by Dmitri K. Belyaev. Belyaev and his brother were geneticists who believed in Mendelian theory despite the domination of Soviet science by Trofim Lysenko, who rejected Mendelian genetics.
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