Lemurs can smell weakness in each other. Duke Today, June 28, 2018. Some people watch the competition carefully for the slightest signs of weakness. Lemurs, on the other hand, just give them a sniff. These primates from Madagascar can tell that a fellow lemur is weaker just by the natural scents they leave behind, finds a study on ring-tailed lemurs led by Duke University researchers. The study reveals that getting hurt dampens a lemur’s natural aroma, and that males act more aggressively toward scents that smell “off.” Picked up by National Geographic.