“Taming the Wild”
by Evan Ratliff
National Geographic, March 2011
[Ratliff notes that the information in this pitch letter has not been verified, and some information changed substantially in the reporting of the story.]
The domestication of animals, anthropologists argue, is one of the most crucial developments in the course of human history. Yet for such a seminal event, the science behind domestication remains surprisingly opaque. Basic questions remain, in particular, about the biological conditions that allowed humans to gain dominion over animals. Why is domestication so rare, for instance, with only 14 of the 145 large mammals ever having been tamed? Why do domesticated animals often differ physically from their wild counterparts—with floppy ears and spotted coats, for example—in similar ways across species? (Something noted by Darwin himself, in The Variation of Plants and Animals Under Domestication.) And perhaps most tantalizingly: why could species like the horse be tamed, while close relatives like the zebra, despite numerous attempts, could not?
Increasingly, researchers believe that the answer to these questions is imbedded in the animals’ DNA, and even in our own genes. Using advanced gene sequencing techniques in species ranging from pigs to domestic dogs to zebra fish, scientists are on the trail of the “domestication genes” that hold the key to tameness and the physical characteristics that go with it. It is a pursuit with implications not just for our fundamental understanding of evolution and animal behavior, but also for the future of food production and the conservation of endangered species through captive breeding.
This story would examine that pursuit, centered around what is widely considered the most remarkable evolution experiment ever conducted. The study, begun by the Russian geneticist Dmitry Belyaev in Siberia in the 1950s and continuing today, involved selectively breeding two sets of wild silver foxes. Those least afraid of humans were mated in an attempt to create a tame population, while another set was selected for aggressiveness. In just 35 generations, the researchers created a group of perfect pet foxes that bond deeply with humans, alongside a group that attacks or flees humans on sight. They’ve done the same more recently in rats and— less successfully, but just as interestingly from a scientific perspective—in minks. Compressing what was assumed to be millennia of evolution into 50 years, they’ve almost single-handedly
established that physical traits like floppy ears, short noses, and spotted coats, “free ride” on tameness genes.
The experiment itself has a strange and colorful history, dating to a time when the Soviet scientific establishment rejected Mendelian genetics. Belyaev’s older brother, also a geneticist, was sent to a labor camp based on his work, and died there. So Belyaev started the fox study in Siberia, away from the eyes of the scientific bureaucracy. Eventually, as attitudes changed, he became a renowned Soviet biologist. Since his 1985 death, a woman named Lyudmila Trut has continued the research, now in partnership with a Russian researcher at Cornell.
With the help of researchers in the U.S. and Germany, today they are using the most advanced quantitative genetics techniques to pursue domestication genes in the foxes and rats. They’ve already shown that tameness is associated with surprisingly small changes in the brain’s gene activation, and undermined some long-held beliefs about the evolution of dogs. They’ve also built a genetic roadmap that they hope will lead them to the genes themselves in the next two years.
Other researchers are attacking the question across a variety of species. Another Russian scientist based in Siberia has a parallel study of pigs, examining the genetic basis of a pig’s fear of humans, while French researchers evaluate how those genes also may regulate the pig’s eating habits. (Scared pigs, in other words, equal skinny pigs.) At a lab at the University of Idaho, and another at the University of Turku in Finland, researchers are studying the genetics of domestication in rainbow trout and zebra fish, to see how the genes of fish change as their behavior adapts to captivity. Those findings that could be significant for the growing aquaculture industry. Still other geneticists are taking apart the genome of cattle and comparing it to samples from ancient cattle bones, and lining up the DNA of the domesticated chicken alongside the wild red junglefowl.
A story that explores these efforts, anchored in the Russian fox study, would offer a wide variety of photo opportunities, across wild and tame species. The Belyaev study has been written about sporadically over the years, but not in tremendous depth, not in a broader context, and not since the researchers have advanced significantly into the genetics phase of the research.
Finally, despite a superficial similarity, this would not repeat the concepts of the 2002 National Geographic story “Wolf to Woof.” Here we will be attacking fundamentally different ground: not showing the history of our pets, but investigating what it means for an animal to be tamed, and the biology underlying animal domestication.