The African giant pouched rat (Cricetomys gambianus) is three feet long from the tip of its nose to the end of its tail and can weigh up to four pounds. Besides its distinction for being a rodent of unusual size, these rats have been trained to sniff out threats to human lives.The nonprofit Apopo (an acronym in Dutch for Anti-Personnel Landmines Detection Product Development) was founded in 1997 by Bart Weetjens, who saw potential in the rats' sense of smell. The organization trains giant pouched rats to detect TNT, an ingredient in most mines, and deploys them on the minefields of Africa. Due to their low weight, there is no danger of them setting off the mines as they search. The rats are led on leashes and indicate the presence of a mine by scratching at the ground. Apopo has trained 150 mine-sniffing rats - check out their website here. You can even sponsor a rat!This week The Wall Street Journal reported another promising application of the giant pouched rats' sniffing acumen: detecting tuberculosis in human sputum samples.  A rat can go through the same number of samples in seven minutes as a lab technician would in a full day. Although the animals detected TB in many of the samples that were missed by humans, they also had a high rate of false positives (indicating the presence of TB when it was not there). The next step is to refine the training process to encourage more accuracy and see if rats could work in real-life situations as well as the lab.  You need a subscription to read the whole article at The Wall Street Journal,  but you can watch a fun video here.