designed for gnawing. The four incisors, a pair on the top and on the bottom, are like chisels. They grow constantly throughout a rat’s life to replace the worn-down enamel. A rat also has twelve tiny molars used to chew food. Between the incisors and molars is a space called the diastema where special cheek folds prevent debris from entering the mouth while the rat is gnawing.
Because we see wild rats eating our garbage, they have the reputation of being dirty animals. They really are quite clean though, grooming constantly by licking themselves and then licking their hands to wash their faces. They also use their back toenails as combs.
Rats communicate with each other through scent, sound, touch, and visual signals. Vision is their weakest sense. They are mostly color-blind and nearsighted, although they see movement extremely well and can see in very dim light. Some domestic rats weave their heads from side to side to improve depth perception and to help them focus on stationary objects. Rats who do this may be especially nearsighted.
Rats, like this Berkshire (front) and agouti (back), are social creatures.
Rats have excellent hearing and communicate with sounds beyond our range of hearing. Baby rats emit ultrasounds to call their mothers, males use them when fighting, and all rats laugh in ultrasound when playing. Rats squeak audibly when annoyed or defensive, and they screech when hurt or terrified. They express other strong emotions such as agitation, frustration, or contentment by grinding their teeth.
Body language is important to rats. They claim territory or declare their status by shuffling or scraping their hands on the ground. In a confrontation, a rat may hold her tail out stiffly and rattle or vibrate it. An aggressive rat puffs out her hair and arches her back and may hiss. In a fight, rats push their shoulders against each other as a test of strength before grappling and biting. They may also stand on their hind legs and box.
A rat expresses submission just as a dog does, by putting her ears back, holding her head down, laying down, or rolling on her back. Some rats seem to wag their tails when happy, and some may shudder or shiver when excited or nervous. A rat stretches and yawns when waking up, but this behavior can also be a greeting. A rat who is playful and excited jumps and twists, scampers, and runs around in circles. A curious rat does a lot of sniffi ng and may rear up on her hind legs. And just like puppies, rats explore new items by licking, nibbling, and chewing on them.
In this temple In India, wild rats are revered and fed by people who visit.
Equivalent Aging Schedule
| Rat Age | Human Age |
| 5 weeks | 10 years |
| 6 months | 16 years |
| 9 months | 25 years |
| 1 year | 35 years |
| 18 months | 50 years |
| 2 years | 65 years |
| 3 years | 85 years |
| 4 years | 100 years |
| 5 years | 110 years |
| 6 years | 120 years |
| 7 years | 130 years |
It is unknown how long wild rats live, although studies have shown the average age of colony members is only six months. Wild rats probably do not live past a year or two. As their reflexes slow down, they are more vulnerable to predators such as owls, snakes, foxes, and weasels in the country, and dogs and cats in the city.
The elephant-headed Hindu god Ganesha is often portrayed on the back of a rat.
Domestication of the Rat
Domesticated rats are physically much the same as wild rats, and they behave much the same as wild rats; however, the behavior of domesticated rats differs from wild rats in several ways. During the process of domestication, rats were selectively bred to be more docile and accepting of human handling and restraint. Domesticated rats are less aggressive, less fearful of humans and new objects, and less predatory than their wild counterparts.
Domesticated rats reproduce more quickly than wild rats, reaching sexual maturity earlier (as early as five weeks) and having bigger litters. These are the same qualities that separate other predatory domestic animals, such as dogs and cats, from their wild ancestors. Domesticated rats are true domestic animals and would have trouble surviving on their own in the wild.
Young domesticated rats do not need to be tamed; they need to be socialized. Every animal species has a critical period of development when it most easily bonds to other individuals. In rats, the critical socialization period is two to six weeks of age, with two to four weeks being the most critical. Handling and petting baby rats of this age for just a few minutes each day ensures that they are socialized to humans, and the more they are handled, the friendlier they will be.
The adaptable wild Norway rat is the ancestor of the domesticated rat.
Fully socialized rats accept people as part of their family, interacting with their two-legged family members as if they, too, were rats. Rats will groom, play, sleep, and eat with the human members of their family. It is this ability to form strong social bonds that makes rats such delightful companions.
Rat lovers come in all ages.
Varieties
Rats haven’t been domesticated long enough for true breeds to develop, but many varieties of rats exist. Currently, there are thirty colors, ten patterns, six coat types, and three body forms that can be mixed and matched, with new varieties being developed all the time. Most pet shops carry only smooth-coated rats in the most common colors—agouti, black, beige, and white—in either solid or hooded patterns. The hooded pattern is unique to rats; they appear to be wearing a colored hood over the head and shoulders, with a stripe or patch of color down the back.
Rats can be found with rex, velvet, velour, or satin coats, and some have hardly any hair at all. Rex rats have curly hair. The velvet coat is short and plush, while velour is short and fuzzy. A satin coat is extra shiny.
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