As a follow-up to this question Do dogs "understand" breeds or size among other dogs? - a similar question about dogs relationship with human sexes. I also often see posts for dog walkers etc where the owner write "My dog is afraid of men". Do dogs really "understand" (or more likely, "instinctively distinguish") that humans can be split into two different sexes and can dogs identify that someone is a man or a woman? And behave differently if it meets a man or a woman?

2 Answers 2


In my personal experience: yes, they can distinguish between human sexes, but it's more complicated than that.

I hope this doesn't get too philosophical, but what exactly is the difference between a man and a woman? Most people think it's an X or Y chromosome, but we don't walk around with little DNA test kits and there are natural occurances of intersex chromosome variations. As far as I know dogs cannot detect pheromones of other species either. So the distinction between sexes is not scientifically objective.

I've never seen a dog make a distinction between boys and girls before puberty. But after puberty, men's voices get lower and often louder than women's. Depending on cultural context you'll also find drunken men far more often than drunken women. You'll find more men in military uniform or overalls than women. Men use different scents in their deodorants than women. Those are clues dogs can pick up and categorize humans by.

It's my impression that most dogs who are afraid of men are actually afraid of abusers. They may have made a bad experience as a puppy being hurt by one specific man and made a mental connection that tells them all men are bad. From an evolutionary perspective this is very healthy - as a dog you don't want to get hit by a horse twice or run in fron of a car. From a social perspective this is problematic because those dogs are afraid of half of the human population.

Some anecdotes that hopefully explain my impressions:

My last dog was afraid of men, because he grew up in an abusive family. We don't know any details, but from his behavior we assume he and the wife/girlfriend where hit by the husband/boyfriend. He nerver let any male strangers touch him, but had no problems being touched by female strangers.

My current dog is afraid of men in green clothing. She was abandoned in the woods and someone with green clothing (probably a forest ranger) picked the whole litter up. She is now part of our family and trusts all of us, but as soon as my dad puts on his green overalls, she acts as if he's a different person, even after he spoke to her with his usual voice and she sniffed his usual scent.

  • Well, for 99 % or so of the human population, the X or Y chromosome is all it takes to distinguish between the sexes.
    – d-b
    Dec 15, 2023 at 14:29
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    Dogs can't really see green (looks similar to yellow or red to them). So it's probably not the green itself she is afraid of but something else.
    – Harry V.
    Dec 17, 2023 at 15:45

Our dog, Mickey, behaves differently with teen girls and young women. His tail will start wagging and he will try to get their attention. He’s happy to be pet by anyone; but he seems to believe young women are a more likely to tell him how cute he is.

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