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The Real Reason Dogs Sniff Crotches

Reading, Girl, Dog, Book, Couch

Photo: statigr.am/heidiheather

This is the third instalment in the Crotch Series. For earlier crotch talk, check out:Part 1: Oh, hello! Why yes, that’s my crotch!
Part 2: Why is a stranger’s crotch more interesting than mine? 

For humans, our crotches are called “private parts” for a reason.

What lies between our legs is our most personal and controlled area, brought into the spotlight by few, like comedians and young pop stars.   

Dogs didn’t seem to get the crotch etiquette memo. You know what I’m talking about. Everybody, at some point, has been confronted with a dog’s head in their crotch, while they’re left thinking, “What on earth are you doing in there?”

A 1991 study set out to explore just what dogs are doing in there: Specifically, whether dogs differ in how they sniff known versus unknown people.

In the study, human subjects, either owners or strangers, were told to lie on the floor while a dog inspected them. The researchers found that not all crotches are equal.

When dogs first approached the human’s body, dogs inspected strangers’ crotch-and-thigh region more than that of their owners, suggesting that upon meeting a stranger, the crotch is an important “get to know you” spot, like looking at someone’s Facebook page.

Not so fast! Could it be possible that, over time, owners trained their dogs (either intentionally or unintentionally) that their crotch is off limits, whereas strangers would never have had an opportunity to enforce a similar rule? If this were the case, then “learning” might explain why dogs go for strangers’ crotches and not their owners’. 

How can we discern whether dogs’ interest in strangers’ crotches is actually about acquiring important information and not simply the product of not having been told, “No”? To answer this question scientifically, let’s take real people — the source of the potential “learning” — out of the equation entirely.

Dolls to the Rescue

Another study did just that. Two identical dolls were placed in a room wearing identical t-shirts, underpants and socks, but there was a catch: one doll wore clothing that a known child had worn for two days preceding the experiment, and the other doll was adorned with clothing worn by an unknown child. As in the other study, dogs were allowed to investigate by sniffing.

Doll Crotches: The Final Frontier

With no living, breathing person in the room to tip dogs off, what would the dogs do? Would the dogs behave differently towards the known versus unknown ”people”? Would dogs’ behaviour suggest that they simply had learned not to sniff their owners’ crotches, but when given the chance, they would love to get in there? Or, would their behaviour suggest that there is something uniquely important about inspecting a new person’s crotch? 

The study found that dogs still investigated differently depending on whether the doll wore familiar or unfamiliar clothing. Dogs inspected both dolls’ crotches but sniffed the crotch of the “unfamiliar” doll more than the crotch of the “familiar” doll. And that makes sense. 

Since both dolls looked exactly the same, dogs had to investigate both dolls’ crotches to make an initial ID. With the known doll, dogs examined the crotch and quickly determined (and I paraphrase), “Hey! I know you!”and then moved on and investigated other parts of the body.

But with the doll wearing an unknown child’s clothing, this was a new crotch, a new person and more to investigate to answer the question, “Who the heck are you?” As a result, the dogs gave more attention to the unfamiliar crotch, the ID zone. It looks like dogs use human crotches to orient themselves to who we are.  

Crotch Morals

The moral of the story: As the holiday season rolls in and a dog you’ve never met comes bounding over at a holiday party, remember that the best present you can give a dog might be hidden between your legs.

References

Filiâtre J.C., Eckerlin A., Millot J.L. & Montagner H. (1990). An experimental analysis of olfactory cues in child—dog interaction, Chemical Senses, 15 (6) 679-689. DOI: 10.1093/chemse/15.6.679

Filiâtre J.C., Millot J.L. & Eckerlin A. (1991). Behavioural variability of olfactory exploration of the pet dog in relation to human adults, Applied Animal Behaviour Science, 30 (3-4) 341-350. DOI: 10.1016/0168-1591(91)90139-O

Julie Hecht is a canine behavioural researcher and science writer in NYC.

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