…oh, if you ever read an issue of X-Men in the 80’s, you know how that ends.
Nosy scientists find people are able to trail scents just like dogs do
MARTIN MITTELSTAEDT
Dogs won’t have to roll over any time soon, but they have unexpected competition in a field they’ve long dominated.
Just like canines, many humans are able to sniff the ground, pick up a faint scent and successfully track it.
The surprising discovery, made by researchers in the United States who are trying to figure out the mystery of why mammals have two nostrils, suggests that people have a much more highly developed sense of smell than is commonly thought.
The researchers found that about two out of three people given the kind of task that would be the joy of any hound managed to find and follow a scent trail spread on a grass field — a very pleasing scent to humans: a faint whiff of chocolate spread along 10 metres.
A paper published in the January issue of Nature Neuroscience also found that humans get better with sniffing out a scent trail over time, which suggests that with lots of practice people may be capable of the kind of tracking previously thought to be the exclusive ability of other animals.
The researchers were the first to admit that having a group of 32 people, comprised mostly of university students, crawl across a field with their noses to the ground carried a whiff of the absurd.
“It seems a little wacky at first glance,” said Rehan Khan, a senior scientist at the University of California Berkeley neuroscience department who worked on the project. “It’s a very strange task for a human, but it’s the most natural task in the world for most mammals.”
He said the tracking test was part of an effort to figure out why mammals have two nostrils, something that isn’t as readily apparent as the obvious utility of having two eyes, which give depth perception, and two ears, which allow for a more accurate sense of where a sound is coming from.
“All mammals have two nostrils, so we were interested in why is this? Nobody really had an answer to this question,” Mr. Khan said.
People rely most heavily on their sense of sight, leading them to under-appreciate their olfactory abilities. “Because we do have this domination in our perception of vision, we don’t think of ourselves as particularly good at smelling things compared to a dog, but that doesn’t mean that we’re terrible,” Mr. Khan said.
By taping one nostril shut, the researchers were able to show that people were far worse at tracking, with the success rate dropping in half compared with both nostrils. That meant only one person in three was able to pick up the chocolate trail. There wasn’t a significant difference in olfactory prowess by sex, with women and men performing about the same.
“Having two [nostrils] permits you to be a more efficient tracker of scents in your environment. In fact, if a dog only had one, we would predict a dog would be measurably worse,” Mr. Khan said.
What seems to be happening is that each nostril draws air from distinct, non-overlapping areas, allowing people to sniff out scent from a wider area.
To find out whether humans got better with practice, the researchers had subjects train at sniffing out the trail three times a day, for three days. The speed of tracking more than doubled with even this short amount of practice.
During the experiment, the test subjects were blindfolded, given full body suits, and wore gloves and earplugs to make sure they were relying only on their sense of smell to find the trail.
When people first try to sniff out a trail blindfolded, it was disorienting. Some were confused, and had no idea of where they were, but “other people got down and they were able to get into it pretty quickly,” according to Mr. Khan.
The tests were funded in part by the U.S. military. It is interested in finding out more about the sense of smell to develop devices that can track scents.