Can Police Dogs Sniff the Difference between Identical Twins?

Police dogs can distinguish between the scents of identical twins, even when the twins live in the same home and eat the same diet. In one experiment, researchers took sweat samples from two identical twins, then placed them in a room with samples from other people. Police dogs were then told to find the scent from a particular twin, and though the twins' genetic material would have fooled a DNA test, the dogs chose the right sample every time.

More facts dogs and scent:

• Scent lineups are regularly used to identify suspects in some European countries. Dogs are given a scent from a crime scene, and they match it to a suspect.


• Dogs' noses are so sensitive that they can detect a body even when it's under running water. Many police units also use "cadaver dogs" that are specifically trained to find dead bodies.


• Most dogs have about 200 million olfactory receptors in their noses, compared with about 5 million in humans' noses. Bloodhounds, known for their powerful tracking ability, have more than 300 million receptors and have been able to track a scent for more than 130 miles (about 209 km).