An ode to the rat
I am a fan of the humble rat. When I tell people this, the most common responses are eye-rolls, shudders, and informal diagnoses of insanity. However, when you look more closely at rats, past their reputation as cunning, opportunistic pests with horrid tails, they can be remarkably fascinating.
My interest in rats began in a meet-and-greet for potential master’s students, and academics seeking students. When the researcher who would become my supervisor told me he studied rats, I mentally crossed him off my list. I wanted to study something that didn’t make people go ‘Ick!’, and rats are firmly in the ‘Ick’ category. When he said his research involved fieldwork on the tropical island of Sulawesi in Indonesia, I developed a sudden passion for rats that was directly proportional to the likelihood I’d get to go to Sulawesi.
The rats of Sulawesi are not like other rats. There are 49 species, found no-where else in the world, and they have evolved in strange and wonderful ways to better exploit the mountainous, tropical forests they inhabit. It’s easy to become fascinated by the process of discovery that comes with these rats; describing new species, exploring remote areas, and finding strange characteristics and diets that make them unique.
So yes, I would study rats, but cool rats. Rats that were nothing like dirty street rats that got into the wheely-bins and scurried through the gutters.
Studying exotic rats was an acceptable compromise to my family. My mother hates rats; the first house my parents bought was plagued by them. An entire cupboard in the kitchen was lost as unrecoverable rat territory. Mum decided to move shortly after my older brother was born, when she was using a broom to shoo rats away in the kitchen and one stood up and barked defiantly at her. Home ownership is not worth the risk that rats may eat your newborn.
Drawn by Les Sprague. Used with permission.
As an animal lover I struggle to live in rentals without pets, where the typical companion cat or dog is not allowed. What pet would my landlord allow? A small animal, something that lived in a cage when I wasn’t with it. The more research I did, the clearer it became. Rats make fantastic pets. And so Mycroft and Pickles arrived.
Like wild rats, domestic rats are highly social and hierarchical. This social behaviour allows them to can bond strongly their owners and cage mates. A domestic rat raised as a pet is just as happy as a cat to curl up on an owners lap or play endless, repetitive games reminiscent of a dog.
However, domestic rats are not cool rats. They are members of the species known as common brown rats (Rattus norvegicus), and are found as a pest throughout the world. They are the species that had so tormented my parents and their newborn son. Whilst not responsible for carrying the fleas that spread the black plague (that honour goes to the black rat Rattus rattus) these rats are despised and hated by much of the population.
Acquiring rats was unforgiveable to my family, and placed me firmly in ‘crazy rat lady’ territory. To this day, when I visit my parents the rats are required to stay in the shed, with only brief visits to the house where they must remain on my shoulders at all times.
My research had led me to rats, and my dabbles in pet ownership led me to the common brown rat. The most successful mammal species on earth, outnumbering us and existing on every continent but Antarctica.
More than being brilliant pets, or horrid pests, many of us owe our lives to the common brown rat, and the scientific advances they have facilitated.
Common brown rats are the first mammal species to be domesticated specifically for scientific research. We have studied rats for hundreds of years now, and have a huge wealth of information on their behaviours, biology and genetics. Many medical and scientific procedures have been developed using the rat, and they are an established part of rigorous, accurate scientific process. Cardiovascular disease, strokes, cancer and diabetes are just a few of the conditions rats have been used to develop treatments for.
Rats are useful for research because they breed quickly, able to reach sexual maturity and begin reproducing in as little as five weeks. This allows scientists to observe processes that take many generations to fully understand. Studying the same processes in humans or primate species would take so long that the researchers would probably be dead (or at least retired) before results started to come in.
Short-lived they may be, but brown rats are also clever. They are an exception to rule of captivity affecting animal brain size. Over several generations, captive animals exhibit reduced brain sizes in response to captivity and increasing tameness. Rats do not; they maintain normal, wild levels of brain size despite many generations in captivity. This well-developed brain can be trained to perform spatial reasoning tasks. Rats are fantastic at learning basic processes for rewards, allowing us to study cognition and motivation.
The common brown rat really is the best all-rounder of human-animal relationships. Our successes in building cities and shipping routes have allowed rats to become the most abundant mammal in the world. They are capable of inspiring fear, anger and distrust in some, whilst others rely on them for loyal companionship. We are reliant on rats for medical advances, and owe at least part of our current understanding of human biology to them. What other animal do we have such a complex relationship of mixed emotions and needs towards? At least we have time to figure it out. The common brown rat is so successful, it’s sure to outlast us.