Although humans and rats seem to be entirely different from each other, they share a surprising number of similar characteristics. These similarities include physical, psychological, behavioral and social characteristics. Rats have a reputation for being disease-carrying, and this is true to some extent, but rats have also been instrumental in saving human lives because of their use in laboratories. Why are they so widely used in laboratories? Because of their similarities to humans.
To look at a rat and a human side by side, you would not think we share similar physical or physiological characteristics, but you would be wrong. Rats and humans are both mammals who give birth to live babies; both are warm-blooded; both have similar organs, including livers and hearts; both have similar nervous systems; both use similar hormones to regulate body functions; and both are susceptible to many of the same diseases.
One study reported by the Live Science website indicated that rats are similar to humans in the way that they reflect cognitively. Rats seem to analyze consequences in a similar way that humans and other primates do. This phenomenon is called "metacognition," and rats and humans both have the ability for metacognition.
Rats have demonstrated their ability to get addicted to substances, just like humans. They develop personality traits similar to humans, being optimistic or pessimistic. Rats also giggle when tickled and apparently look forward to having sex. These are similar to human characteristics. In addition, like humans, rats learn to avoid unpleasantness and seek reward. Based on their personalities, they will exhibit varying degrees of tenaciousness to get what they want or to avoid what they don't want.
Rats exhibit group behaviors similar to human social behaviors. For example, when overcrowded, male rats have been known to form gangs and exhibit dominance over other rats. In addition, it has been observed that rats develop social behaviors from infancy, which is a similar characteristic to humans.