Rats are commonly viewed as pests, associated with urban decay and disease, a perception largely shaped by historical events like the Black Death. This view often overshadows the surprising ways these rodents contribute to human welfare and the balance of nature. Far from being merely vermin, rats play a significant role across a variety of fields, from laboratory breakthroughs to global humanitarian efforts. Their unique biology, intelligence, and adaptability have been harnessed for diverse positive outcomes.
Pioneers in Medical Research
The laboratory rat, specifically the brown rat (Rattus norvegicus), is an indispensable model organism in biomedical science, having been used in over 1.5 million biomedical studies. Their value stems from a close biological and genetic similarity to humans, sharing approximately 95% of their genes. This physiological likeness allows scientists to study complex biological processes and disease mechanisms with a high degree of translational relevance to human health.
Standardized rat strains, such as the Wistar rat, are intentionally bred to have nearly identical genomes, ensuring researchers can reliably attribute experimental results to the variable being tested. Their relatively short lifespan and rapid reproductive cycle also make them ideal for multi-generational studies, allowing for observation of the long-term effects of drugs or genetic changes. Researchers use these models extensively in drug development, toxicology testing, and for modeling human conditions like diabetes, hypertension, and various cancers.
Modern genetic engineering techniques, including CRISPR/Cas9, allow scientists to create “humanized” rats that express specific human genes or diseases. This capability enables the creation of highly specific models, such as rats with gene modifications that mimic human breast cancer or Alzheimer’s disease, providing unprecedented insight into the underlying causes of these disorders. The ability to precisely manipulate the rat genome continues to advance the understanding of biological processes, from neural differentiation to the effects of gene function on development and disease progression.
Specialized Detection and Service Roles
The exceptional olfactory capabilities and intelligence of certain rat species have been harnessed for specialized humanitarian work outside of the traditional laboratory setting. Organizations like APOPO train the African giant pouched rat (Cricetomys ansorgei), nicknamed “HeroRats,” for their strong sense of smell and light weight. These animals are trained using operant conditioning, which rewards them for locating a specific target scent.
Their primary role is the detection of landmines and unexploded ordnance in former conflict zones. Because the giant pouched rats weigh only about two pounds, they are too light to detonate pressure-sensitive mines, allowing them to safely search large areas. A single trained rat can clear an area the size of a tennis court in just 30 minutes, a task that would take a human technician with a metal detector up to four days. These efforts have been instrumental in returning millions of square meters of safe land to communities in countries like Cambodia and Mozambique.
Rats are also used in public health for the rapid screening of samples for tuberculosis (TB). These TB detection rats are trained to identify the unique scent of the bacteria in sputum samples. One rat can evaluate 100 samples in 20 minutes, which is the equivalent of two days of work for a lab technician using conventional microscopy. This speed and sensitivity have significantly increased detection rates, identifying thousands of TB-positive patients who were initially missed by standard methods, preventing the further spread of the disease.
Unexpectedly Intelligent Companions
The domesticated rat, often called a “fancy rat,” has grown in popularity as a companion animal due to its high intelligence and affectionate nature. These pets are descendants of the brown rat and have been selectively bred, resulting in animals that are calmer and more comfortable with human interaction than their wild relatives. They are known for forming strong bonds with their owners and often seek out human attention.
Rats display an advanced level of cognitive ability, demonstrating problem-solving skills that allow them to navigate complex mazes and learn a variety of tricks. Studies have shown that rats possess metacognition, the mental ability to reflect on what they know or do not know, a trait previously documented only in humans and some primates. They are highly social animals that thrive on companionship, often requiring a partner or small group to maintain their psychological well-being. They also exhibit complex social behaviors, including empathy, sometimes choosing to free a trapped cage-mate even when offered a separate reward.
Role in the Ecosystem
While the negative impacts of wild rat populations are frequently emphasized, these animals have a distinct and important function within natural ecosystems. As highly adaptable omnivores, they play a considerable role as scavengers, consuming organic waste and carrion, which helps to clean up the environment and recycle nutrients back into the soil.
Their feeding habits are also integral to the reproductive cycle of various plant species, particularly through seed dispersal. Rats engage in scatter-hoarding behavior, where they bury seeds in multiple locations to store food for later consumption. While many of these caches are later retrieved, a significant number are forgotten or abandoned, which provides an opportunity for the buried seeds to germinate and establish new plants. This accidental gardening is particularly impactful in forest regeneration and the distribution of certain tree species.
Rats also occupy a foundational position in the food chain across a wide range of habitats. They serve as a primary and consistent food source for countless predators, including snakes, owls, foxes, weasels, and various birds of prey. Their abundance and high reproductive rate support the populations of these other animals, making them a crucial link that transfers energy from lower trophic levels to higher ones. This function helps to maintain the balance and health of predator-prey dynamics within their natural communities.