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Sniff, sniff…

 

 

How does your dog smell?

 

Wonderful

 

9 September 2024

By Gavin Cox and Lucien Tuinstra

Reprinted from Creation.com — Creation Ministries International

 

An old British joke about a dog’s ability to smell is: “My dog has no nose.” When asked: “How does he smell?” The answer is: “Terrible!” For dog owners, this somewhat silly double-entendre1 brings to mind their furry friend’s keen sense of smell. According to Profs Stuart Burgess and Andy McIntosh: “The area in a dog’s nose with scent receptors is more than ten times larger than the equivalent area in humans. A dog also has up to a hundred times more receptors per square centimetre. … The part of the brain that processes smells is forty times larger in a dog than in humans …”.2

This is of particular importance for wild dogs (‘Smell in the wild’, see below) to hunt down their prey. Without their much-needed noses, they wouldn’t be able to sense the world around them nearly as well.

Two recent studies have demonstrated just how keen our pet pooch’s nose really is.

1. Had a hassled day?

You’ve come home from a tense day at work and are asked by your loved one(s) “How are you?”. Chances are ‘Fido’ will already know how you’re feeling. That’s one reason dogs have been called ‘man’s best friend’. Dog owners know their canine companions are highly intuitive and can ‘read’ their moods. New research from Queen’s University Belfast3 has demonstrated that dogs can smell human stress responses—specifically in their owner’s sweat and breath. People naturally avoid such things, but dogs can pick up important emotional cues from them.

A stressful test

stressed-smell

Fig. 1. Clockwise from top right: Fingal, Treo, Winnie, and Soot indicating their choice on the three samples—stressed, non-stressed, and blank.

 

The study involved four dogs—Treo, Fingal, Soot, and Winnie—local pets whose owners were happy for them to participate. Altogether, 36 human subjects were asked to perform a stress-inducing mental arithmetic test—counting backwards aloud from 9,000 in steps of 17, without pen and paper. Two researchers present gave ‘stern-voiced’ prompts such as, ‘It is very important that you perform the task as quickly and efficiently as possible’, and, ‘You must keep going until the task is completed.3 That certainly would be stressful for most!

The volunteers’ sweat and breath were sampled before and after this task. The participants also self-reported their stress levels before and after the test. Researchers only used samples if the volunteer’s heart rate and blood pressure had increased. In humans, stress is associated with several physiological changes, including the release of the stress hormones adrenaline (epinephrine in the US and Canada) and cortisol. In response to these, certain chemical markers make their way into the human subjects’ sweat and breath. The dogs could detect these chemicals.3

The samples, rather like an ‘Eau de Anxiousness’, were presented to the pooches in sniffable vials, to see if they could tell the difference between stressed, relaxed, and blank samples. The dogs had been trained to respond to the stressed smell (fig. 1) in the absence of their owners so as to avoid any visual or audible cues. The test was ‘double-blind’, designed to be completely neutral and free of inadvertent interference or bias. One researcher knew which sample was the stress sample, as he rewarded them with treats when they identified it. But he was hidden so the dogs could not get subtle cues from him. The other researchers didn’t know which labelled sample was which.

The dogs were able to differentiate the individual volunteer’s ‘stress sample’ from their ‘calm sample’ in 675 out of 720 trials—almost 94% accuracy.

One of the researchers, Clara Wilson, explains:

The findings show that we, as humans, produce different smells through our sweat and breath when we are stressed and dogs can tell this apart from our smell when relaxed—even if it is someone they do not know. It also helps to shed more light on the human-dog relationship and adds to our understanding of how dogs may interpret and interact with human psychological states.4

The paper opens with the usual evidence-free platitude to evolution before commenting accurately on dogs’ amazing sniffers:

Odours emitted by the body constitute chemical signals (chemosignals) that have evolved for communication, primarily within species. A canine’s sense of smell provides critical information, essential for being aware of potential predators, locating food, identifying conspecifics [members of the same species] (and their reproductive status), and enabling recognition of familial members.3

This research highlights the brilliant design present in the canine kind (see ‘Smell in the wild’ below) and their ability to detect stress in humans from even the tiniest traces of hormones. The researchers concluded that:

The results of the current study could have further applications to the training of anxiety and PTSD [post-traumatic stress disorder] service dogs, that are, currently, predominantly trained to respond to visual cues.3

Now that’s something not to be sniffed at!

2. Electrifying sensation

English Springer Spaniel Breed Guide - Learn about the English Springer ...

Meet Jac, a springer spaniel. He can smell hydrocarbon particles (from oil or gas) escaping from buried cables as deep as two metres (6½ feet) down, even through earth and tarmac. Some buried high-voltage power cables are filled with oil (along with the conducting wire). Oil-filled cables can better withstand the greater temperatures of larger currents. The oil also fills any voids, reducing weak spots that might otherwise lead to faults. Oil leaking from damaged sheathing means the cable is more prone to failure. Most cables are buried 40–80 cm (c. 15–30 in) deep. Astonishingly, dogs can detect levels down to parts per billion (ppb), which is vanishingly small. Man-made leak detectors can generally only measure parts per million (ppm) levels, and require their components to be regularly replaced.5

This is where Jac comes in. The lowest-paid staff member of SPEN (Scottish Power Energy Networks), his remuneration consists primarily of treats—yet he is also the most efficient worker, with a 100% success record.6

Note that cable leaks are not the same as electrical faults (involving a short circuit) which produce a different smell. Dogs have been used to detect such smells for years.7 This is helpful at a smaller scale in quickly pinpointing where an existing fault is at the domestic/street level without having to disconnect many residences to undergo testing. Jac’s skills, on the other hand, are used to avoid larger-scale problems which may result in many people ending up in the dark.

Smell in the wild

Grey Wolf (Canis lupus), in forest, captive, USA | #15318701 | Nature ...

Domestic dogs (Canis lupus familiaris) descended from wolves (Canis lupus), which, like jackals, coyotes, etc., are from an original wolf-like pair of canids that came off Noah’s Ark.8 It is likely that wolves can smell even better than domestic dogs; that is certainly true for jackals, as CMI has reported before. However, such wild dog species are not easily trained, if at all. Domestic dogs, on the other hand, are typically much more cooperative. So when scientists crossed a jackal (likely the non-African species Canis aureus) with a husky, the result was a dog with improved smell capabilities compared to domestic dogs—but much more manageable in temperament than wild jackals.9 Note that from the jackal’s perspective, smelling capabilities in the new pups have been diminished.

Evolutionists need to explain where the sophisticated olfactory prowess came from in the first place.10 Genetic information to build scent receptors is required, but this alone would not suffice, just like a man-made sensor is no good unless the signal is used to alert its operator. Processing capability is needed, and so the dog’s brain (olfactory cortex) needs to be programmed to deal with the incoming signals. Lastly, the hardware of the sensing device (the dog’s nose) needs to be connected with the hardware (brain) running the software to interpret the signal; the wiring between the two is done via olfactory nerves, which also require genetic information in order to be constructed. The olfactory cortex does not keep the received signal information to itself, but links with other parts of the dog’s brain to react to the smell experience.11 The notion that this came about by chance mutations selected by randomly occurring environments seems, well, barking mad.

Conclusion

Our furry friends really are superbly equipped with an ability to sense and detect their environment—including their owner’s stress—that makes human-made sensors pale into insignificance. These examples of dogs’ abilities to sniff and smell highlight once again the creative genius of God.

Posted on homepage: 9 September 2024

References and notes

  1. ‘Smell’ can have two different meanings, ‘to sense odours’, and ‘to give off a bad odour.’ Return to text.
  2. Burgess, S. and McIntosh, A., Wonders of Creation: Design in a fallen world, Day One Publications, Leominster, UK, p. 26, 2017; Return to text.
  3. Wilson, C. et al., Dogs can discriminate between human baseline and psychological stress condition odours, PLoS ONE 17(9):e0274143, 2022. Return to text.
  4. PhD student at Queen’s University, Belfast, Department of Psychology, Stress has an odor and dogs can smell it, sciencedaily.com, 29 Sep 2022. Return to text.
  5. Indispensable leak detection, manufacturing.net, 3 Apr 2013. Return to text.
  6. Environment, shropshirestar.com, 22 Nov 2022. Return to text.
  7. Intero—The Sniffers, Use sniffing dogs to detect electrical short circuits, youtu.be/BwY0qibmvsc?t=40, 19 Aug 2015. Return to text.
  8. Guitard, C.J., Creationist modelling of the origins of Canis lupus familiaris—ancestry, timing, and biogeography, J. Creation 32(2):20–28, 2018; creation.com/dog-origins. Return to text.
  9. Focus, Sniffer dogs, Creation 26(1):7–9, Dec 2003; creation.com/focus-261#sniffer. Return to text.
  10. Walker, T., Super scented: Aerodynamics of odours in a dog’s nose, Creation 32(4):56,2010; creation.com/sniffer-dog. Return to text.
  11. Jenkins, E., DeChant, M., and Perry, E., When the nose doesn’t know: canine olfactory function associated with health, management, and potential links to microbiota, Front. Vet. Sci., 29 Mar 2018.

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