The giant hissing cockroach is not a creature most people would want to encounter in the dark, let alone pick up and stroke its polished, mahogany-coloured back.
After just a few petting sessions, a University of Guelph researcher has demonstrated beyond a doubt that the rodent-sized roaches, which come from the island of Madagascar, not only get used to humans, but can tell them apart.
Psychology professor Hank Davis enlisted student Emily Heslop to handle the horned arthropods for two minutes a day. Within a few sessions, all but two stopped their defensive behaviour when she picked them up.
(The two holdouts were "damaged goods," according to Prof. Davis: One had a broken leg and the other had both antennae broken.)
When Ms. Heslop prevailed upon one of her roommates to act as the new handler, the cockroaches were infuriated by the unfamiliar pheromones.
"They actually spit on her hand, and it was quite a lot of liquid," said Ms. Heslop, a native of Caledon East, Ont., who had never seen a cockroach before she signed on to Prof. Davis's experiment. "It just seemed very dramatic."
Prof. Davis has been conducting the same experiment in more than a dozen species of animals since publishing The Inevitable Bond: Examining Scientist-Animal Interactions in 1992 with Diane Balfour.
In it, they argued that the close relationship scientists develop with research animals allows the creatures to get to know them and to anticipate what is going to happen to them. If an animal associates a certain researcher with a painful shock, for example, it will start preparing, psychologically and metabolically, for what is about to befall it.
"That's Pavlovian conditioning," Prof. Davis said. "In a sense, you become a walking metronome, or a walking buzzer, or a walking bell."
The implications for research are profound, and Prof. Davis has now proved everything from penguins to llamas to chickens to bees can differentiate between individual humans.
"The two-word message is: Know it. Because things will turn up in your research that might be a little puzzling to you. And they're not as puzzling if you realize: 'This guy knows me. This guy also knows, when I pick him up, x, y, and z are going to happen to him.' "
It's not surprising that social animals such as bees can differentiate between a worker and a drone, since their survival depends on it. Prof. Davis doesn't ascribe any anthropomorphic significance to the fact that cockroaches can tell his scent from Ms. Heslop's. He said the handlers were just tapping into the animal's ability to tell one roach from another.
Prof. Davis admitted that he and Ms. Heslop are not "bug people," and both were creeped out when they first turned over one of the paper egg cartons in a 20-gallon aquarium and saw hundreds of cockroaches skitter away. A collective hiss, not unlike that of a cat encountering a dog, emanated from inside.
"The first visit, we both just stood there taking some very deep breaths," he said. "It was not easy. I'm sure we both had thoughts: 'My God, am I going to be able to do this?' "
The professor and the student are now over their fear of roaches, something Prof. Davis figured is an evolutionary remnant from the days when our ancestors actually had something to fear from insects.
In fact, he would take one home as a pet, if he could, and some people do, according to the Pet Arthropod page (www.key-net.net/users/swb/pet--arthropod).
By the end of the Guelph experiment, which required Ms. Heslop to visit her hairy-legged subjects for two minutes a day, the cockroaches may have preferred her company to that of her roommate, but she had her favourites, too.
"Basically, it was the nice ones," she said, laughing.