According to a new study published in advance on the Nature Neuroscience website, humans can track scents in exactly the same way as dogs.
Jess Porter and colleagues recruited 32 undergraduates from the University of California at Berkeley for their study. They laid down a 10-metre-long trail of chocolate essence in a field. When the students were then blindfolded and asked to try and track the path of the scent, two-thirds did so successfully. Four of them were then trained to track scents, three times a day for a period of three days; after training, they were able to track the scent more accurately than before.
As the film clip below shows, the students sniffed at the ground repeatedly to track the scent, in exactly the same way a dog would. The participants didn’t perform as well when one of their nostrils was blocked, or if they wore a nasal ‘prism’ – a device which combines the air that would otherwise enter each nostril separately. This shows that the stereo effect of smells entering both nostrils is important for human olfaction.
Gordon Shepherd, a professor of neurobiology at Yale, and an expert on olfaction, has, in recent years, argued that the human sense of smell is better than we think. “This shows that in a few training sets, humans can achieve something that other animals spend their life being trained to do”, he says. Whereas dogs practice tracking scents from birth, we humans may merely be out of practice. As our ancestors adopted bipedalism, the sense of vision became more important, and that of smell less so. According to Shepherd, although humans have far less olfactory receptor genes than dogs, we may compensate for this by increased higher order processing of olfactory information.
However, although humans may be capable of tracking scents in exactly the same way as dogs, when it comes to the range of smells that can be detected, dogs beat us hands (or should that be noses?) down.