In defence of the rat
The many talents of a much-maligned rodent
By August 2015
One day, as I opened a barrel of chaff to feed our horses, a large rat with a long, grey slithery tail emerged on the rim. I expected him to flee, but he just looked at me for several seconds, twitching his whiskers and eyeing me with a relaxed, even insouciant, air. Then he seemed to shrug his shoulders as if to say, “So? This is what we rats do.” And he dived back in. Peering down I realised there was a whole family of rats snuggling together among rat poop and chaff. They looked up at me calmly. Disconcerted by their aplomb in the situation, I carefully replaced the lid, walked back to the house and, over a cup of tea, considered what was to be done.
We had lived with colonies of rats for a long time. If you went into the chicken coop at night it was like the nightmare in George Orwell’s 1984. The ceiling rafters were covered in rats looking down at you. Hundreds of them. They ate the chicken pellets, which we obligingly supplied in unending amounts. One long dry summer they ate an entire crop of lemons from a tree, leaving the branches bare and the trunk pitted with teeth marks. They shinnied up the plum trees outside the living room window. The dappled light from the tree would be shaking and dancing while the rats balanced on thin boughs, munching plums, long tails dangling. A neat stack of lush, oaten hay intended to last our horses all winter was transformed, overnight, into a dishevelled mound. The rats wrestled the hay out of its baling twine and chomped their way through the oats, leaving nothing but chewed stalks.
Now I held them captive. Surely we (well, actually, he – my husband) should “do something”. Despatch them. However, he lowered his spectacles over the book he was reading and pronounced them “sweet”, then made a distinction that only an intellectual could make. There was a difference, morally, between the act of killing germ-infested, city-dwelling rats and these clean bush rats. What a difference an adjective makes! I thought the firmness of this distinction unlikely; besides, he looked rather too settled – at his desk with an interesting book opened – for me not to feel there was some self-interest in his rationalisation for inaction.
The burly man delivering feed had other ideas. He shrieked and leapt into the air when he disturbed a rat nest while offloading hay. He claimed they were the largest rats he had ever seen, and offered to bludgeon them to death. Other methods were equally cruel: rat poison causes internal bleeding. The reality of killing animals is always nasty.
Moreover, I had recently discovered we would be killing animals who laughed. Jaak Panksepp, an animal behaviourist and neuroscientist from Bowling Green State University in the US, has done research to show rats are capable of play and of expressing positive, even joyful, social emotions with laughter. He calls this “primordial laugh” the “ancestor” of the human laugh. It comes in bursts of high-frequency 50-kilohertz squeaks or chirps, during play or when being tickled by human handlers. Before Panksepp began tickling rats, it was thought only humans and higher primates showed the capacity for such expression.
Panksepp discovered that, just like young children, rats love being tickled. They laugh more when tickled than during any other activity, and go preferentially and with pleasure, time and again, to the hand that tickles. If they feel depressed, or are frightened by the ominous whiff of a cat, they laugh less. Some rats, Panksepp discovered, are more optimistic than others, so chuckle more than their gloomy cousins. Baby rats prefer to play with their cheery elders rather than the grim ones. Rats will press a lever repeatedly to get the fun of a tickle. There is footage on YouTube of a rat splaying its little limbs in ecstasy as it is tickled.
Then there are the rats who are using their superb sense of smell to detect unexploded landmines and tuberculosis in places like Angola and Mozambique, saving countless lives. Apopo, a non-profit aid organisation that trains these “HeroRATs”, is the brainchild of Bart Weetjens, who kept pet rats as a boy. Weetjens complains that rats have had a bad press for centuries. They were blamed, wrongly it turns out, for spreading the Black Plague. The real culprits were fleas and person-to-person infection.
While at the University of Antwerp, researching the destruction done by landmines in Africa, Weetjens recalled his pet rats’ intelligence and acute sense of smell. Apopo uses African giant pouched rats (Cricetomys gambianus) because, to compensate for weak eyesight, they have a superb sense of smell. Growing up to 1 metre (tip to tail), these rats are still so light they never trigger a detonation. No Apopo rat has ever been killed on minesweeping duty. They are every bit as trainable as dogs but cheaper to keep, require only avocados and bananas as reward, and take nine months to train but live for eight years. When active service ends, they retire to play with those still working.
To find a mine, a rat is put in a harness on a long leash, and it speedily scampers about, sniffing for TNT. On finding a mine it receives a reward and devours it with evident pleasure before scurrying onward, nose to the task. Rats can clear 200 metres of mine-laden territory in 20 minutes, whereas humans, at much greater risk, would take five days. In Mozambique, the Apopo rats have so far cleared 11 million square metres and destroyed more than 13,000 landmines.
Apopo-trained rats also save lives by detecting tuberculosis, and are faster and far more reliable at finding the TB bacteria in sputum than human lab technicians. They have analysed more than 300,000 samples, and identified more than 7000 cases of infection not picked up by human lab technicians. They have increased TB detection rates by 45%.
Rat trainers like Francisco Pedro, from Angola, get very attached to their rats. “When there are rats in the house,” he told New York Times journalist Nicholas Kristof, who was visiting to see the HeroRATs at work, “I just shoo them away. I can’t kill rats now.” Pedro has a point. It is not hard to kill “vermin”. It is harder to kill a sentient being who plays, laughs and expresses joy, one intelligent enough to be trained to save human lives.
After finishing my cup of tea, I went back to the shed. I lifted the lid and tipped the barrel holding its lively cargo downwards. Eleven rats spiralled into the air in graceful curves and dived into warm tunnels in the hay.