The vast majority of people can identify other people's sex; so why the pretence that men are women?

With regards to gait, wasn’t there an experiment where males and female skeletons were modelled walking using software and the joints such as hips, knees and ankles and shoulders were highlighted with dots. And so when the skeletons were removed and just the joint dots were shown walking humans could still quite reliably sort the clips into male and female skeletons.

The brain used the ratios visible and the hip width, and hip to knee to ankle alignment.

I will see if I can find it.

Also, sex sorting facial recognition using software seems to be reliable enough in detecting male vs female. It may have some trouble with females on testosterone or with males who have had their faces peeled back and bones shaved and remodelled.

Not sure why it is so implausible that some people are more attuned and can tell more than others.

My OH was in the gym the other day when a woman came in, stripped naked and got dressed in front of them all. No one dared say a thing . So it’s working the other way too. I bet many of those men felt very uncomfortable. OH certainly did.

That’s an interesting thought. What if all the women in Afghanistan decided they are men so they have access to education and jobs?

Yes true re the pelvis; but humans have also evolved to find wider hip ratios in females attractive, so it’s all bound up together. Plus gait isn’t just a function of the pelvis, but of lots of things - height and size, for one - which we also use to sex each other, even though aggregate height differentials didn’t evolve specifically because of that. But evolutionary change is not fixed or tidy to one specific reason - nothing evolves specifically for something anyway; it just randomly happens to benefit it and it often randomly benefits other stuff too.

Plus gait is also heavily socialised, too - and it might well be that what we perceive about gait is social as much as - or even more than - physical. We still use it though; if a characteristic can be reliably used to help us determine what sex someone is, it doesn’t in the end always matter how much it’s social or how much it’s physical, because we always use a combination of both.

The key thing is that we also easily pick up changes in the social display of sex markers and apply them, too, as part of the whole picture - that’s why we can usually tell even if someone changes posture or clothes or mannerisms; it’s a composite of lots of factors and because it’s a composite it’s far more accurate.

On gait, humans have different gaits because of the compromise needed in the female pelvis for a biped to give birth to an infant with a big head. There's a functional reason, it didn't evolve for the purpose of allowing skeletons to be accurately sexed but handily it serves that purpose.

So many words. But to summarize.. with 100% accuracy humans of normal intelligence can correctly sex other humans. And even if, by some slight of hand a mythical trans person could pass clothed, they could not ever pass unclothed. Which means they do not pass. They wouldn't pass in the gym, in a medical examination, on the beach, in a changing room or in bed. Which means they do not pass full stop.
I could pretend they do. But I don't want to.

Of course one of the reasons biologists argue that we do have permanent secondary sexual characteristics is to compensate for diminished sense of smell compared to some other animal species. Presumably adult cats don’t need to have permanently visible mammary glands because they can sex each other in different ways. The gait of a male and female cat isn’t markedly different, because they can sex each other easily by scent a mile off. (Though female cats are in aggregate still smaller on average than males.) We find smell less easy to perceive - which isn’t to say that it isn’t important, as pp have pointed out above. But we have evolved evolutionarily to sex each other just as accurately by all the other visual and voice indicators that posters have mentioned. It’s why children don’t visibly acquire adult secondary sexual characteristics until sexual maturity. They indicate sex and potential fertility.

The “oh you can’t tell” brigade have a chronic case of inability to accept that we’re actually embodied animals, and we can’t just live only in our minds and fantasies and remake our bodies accordingly (or live in our presumably higher “intelligence” than the boring old dogs…?) It tends to be a delusion of teenagerhood for the most part, that denial of the body.

And what they don’t like about older adult women - especially those who have had children - is that we largely know that we can’t escape our embodied animal nature.
Anyone who’s been able to smell their baby’s stuff out of a nurseryload of clothes, or seen a primary school kid pick out a classnate’s jumper by smell, knows how animal we really are.

Oh dear! I think you need a good basic animal biology textbook. Some animals and birds have visually clearly sexually dimorphic features. Others don’t. They might not look like they do, especially to us, but they still have a sex.

That it’s hard for humans to sex a penguin, say, or a robin, or even a cat; does not mean that it’s hard to sex a chaffinch, or a deer, or a human.

Or that because it’s hard for even an expert to sex a penguin, therefore that humans, a visually sexually dimorphic species, can’t distinguish sex in each other.

Humans, of course, have evolved to display some secondary sexual characteristics as permanent, which in other mammals only appear at limited times in relation to reproduction. Women have breasts, where in other mammals milk glands only become visually evident during lactation. And just because cats don’t have breasts doesn’t mean we can’t tell that female humans do.

Or that animals can’t tell! You must not have any animals. Cats and dogs can clearly tell that women and men are different!

And how do you even know a dog actually understands sex differences in humans?

My granddad's dog was very mistreated by men as a puppy. He was aggressive toward men regularly. The only woman he ever showed aggression towards was wearing her BF's pre-worn jumper.

But you just move the goalposts every time anyone argues anything.

It's obvious that knowing sex is innate and important. Some variation around the edges is normal. But the core is that we know. Not because of dress or gender performance but because of bone deep differences. Gait, body shape, voice, smell, hip to waist ratio, arm length and on and on and on. There are so so many differences. Just flat pictures of faces, macaques were 90% able to tell the sex of humans. Just 2D faces.

It's the emperors new clothes.

Predictable.
You're right I don't have a dog, but only because my old boy died this year. He could 100% tell men from women and dogs from bitches.

Good description of yourself I’d say.

The point is there were no scent based in group markings so smell was most likely not used by prehistoric women to sniff manliness. In fact, humans used to mask their scent as protection from predators (sabre tooth tiger anyone?). You said there is “no evidence” prehistoric women weren’t “using their noses” to tell a man from a woman. There is evidence.

No evidence, no logic and it would seem no dog.

Sure it does. In group markings were 100% visual, not scent. So, there’s your evidence that smell was not important.

No. The 'group markings' distinguishing between males and females aren't artefacts. They exist now, sure as heck they existed in prehistoric times. Completely separate issue to whether they used visual group markings.

This is irrelevant unless you believe women are dogs. We are not dogs. We haven’t evolved anything near the sense of smell a dog has. In fact, human evolution has trended towards worse and worse sense of smell.

And how do you even know a dog actually understands sex differences in humans? Are you a dog whisperer? Do they talk to you?