Often dismissed as pests, rats have long been misunderstood. But the African giant pouched rat (Cricetomys ansorgei), the world’s longest, is challenging that perception. With its intelligence and super sense of smell, this species has captured the interest of scientists in Tanzania, who now plan to use it as a crime fighter against illegally trafficked wildlife parts.

This story starts in the 1990s, when industrial engineer Bart Weetjens was looking for viable technologies to detect landmines in countries in the Global South. He then had a thought: Why not use rats? They’re cheap, possess remarkable olfactory systems, and are social and intelligent animals, contrary to popular belief. And so Weetjens founded, a nonprofit rat training organisation in Tanzania, home to the largest and longest-living rat species.

Some of the African giant pouched rats trained by APOPO can live up to a decade, while typical domestic rats typically live only two to four years. This longer lifespan, along with their exceptional sense of smell, has made the African giant pouched rat of invaluable service for many years in various projects. Previous generations of these giant rats have successfully assisted in landmine detection, which was Weetjens’s initial goal, and in detecting tuberculosis.

Now, the rats have been trained for a new...