Most people (unfairly) think of rats as dirty, disease-ridden pests. But thanks to cutting-edge science, rats may be the key to eradicating a deadly disease -- and saving human lives.
Scientists in Tanzania have trained giant rats to smell tuberculosis, a disease that killed 1.3 million people in 2012. They use a clicking noise in the lab to communicate to the rats when they sniff out a correct sample, and the rats are rewarded with a banana treat. This is repeated until the rats are expert TB sniffers -- so skilled that they detect some cases that conventional testing methods miss.
BBC Earth compared one of these disease-sniffing rats with a famed human nose -- and the result is astounding: