LiveScience provides a brief background on the study, which uses a population of rats now almost 40 years in captivity:
"The roots of this study date back to 1972 when researchers in Novosibirsk, in what is now Russia, caught a large group of wild rats around the city. Back at the lab, the researchers arbitrarily separated the rats into two groups. In one group, called the tame rats, the scientists then mated the friendliest rats, those that tolerated humans, with one another, and in the other group they mated the most aggressive rats with each other. "
The study itself includes more detail on the development of its subject population:
"To select the animals, their response to an approaching human hand was observed, and the rats showing the least and the most aggressive behavior were allowed to mate within the two lines, respectively. The initial response to selection was rapid and then slowed, so that little change in behavior from generation to generation has been observed in the last 10–15 generations, although the selection regime has been continued to the present. Today, the 'tame' rats are completely unafraid of humans, they tolerate handling and being picked up, and they sometimes approach a human in a nonaggressive manner. By contrast, the 'aggressive' rats ferociously attack or flee from an approaching human hand."The rapid development of 'tameness' through selective breeding is interesting to those of us who believe domesticated animals can be produced rather quickly. The remarkable Russian fox experiment is relevant here and is referenced in this rat study. There is an ongoing debate about the possibility of rapid domestication, even numerous independent domestications, in ancient dogs. In the falconry context, I'm convinced that selective breeding of Harris hawks (Parabuteo unicinctus) has produced demonstrably tamer and more cooperative birds in as few as five generations---I've been witness to this in my lifetime.
The popular reporting on this study seems to focus on the notion that domestic animals and their wild counterparts could be separated by few or even a single gene; that somehow all of what makes a "wild animal" wild is encapsulated in one trait.
As anyone who has lived and worked with animals both wild and domestic can tell you, it's nothing like that simple.
Animals, regardless their origins or number of generations in captivity, are incredibly (irreducibly) complex beings, individuals every one. Their complexity mirrors their environments, which even in the Spartan conditions of a laboratory may be more variable than we like to assume. In "the wild," those variables are innumerable and subject researchers to principles of uncertainty, acknowledged or not.
The result is enormous diversity and confounding truths. Very tame animals, for example, are common in the wild. Island endemics like those of the Galapagos are well known, but any falconer with sufficient experience can tell of wild-taken hawks flying freely to hand in a matter of days and behaving entirely at ease in human company. Steve's falconry mentor even had a pair of free-roaming goshawks eating from his hand.
Conversely, stories of domesticated dogs attacking the hand (this study's key signature of the 'wild type') are so commonplace as to serve as the classic example of what is not news!
What can the science of genetics tell us about these cases?
Volumes, I'm sure. But I'm equally sure that the complicated truth about our genes and our environment will never be wholly revealed in the lab. It may never be wholly revealed at all, but merely intuited and approximated by those (like falconers, sheppards, hunters) whose lives intersect and entwine with wild and domestic animals. For many, that will be revelation enough.