Rat tails can signal how they’re feeling (Kelly Lambert, CC BY-SA). I had never seen this in my decades of working with rats. Reviewing the video footage, we found that the rats trained to anticipate ...

All trained rats wear a harness equipped with a ball on their chest. When they detect a target, they signal their trainer by pulling the ball, which triggers a sound to indicate their discovery.

The rats learned to signal for pangolin scales, rhino horn, elephant tusk and African blackwood, which is popular for use in musical instruments. Eventually, ...