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Comment by tomlockwood | Hacker News Reader

What tests with what results would conclusively show which individuals went down which pathway?

Depends why you need to know and with what level of accuracy. Just looking at their face is about 96%-98% accurate[0], and becomes even more accurate when other cues are available such as voice, gait, and build. For casual purposes, humans are incredibly good at predicting sex, without any technology or scientific understanding. One might speculate that being able to accurately find a mate is an evolutionary advantage.

For the last few fractions of a percent accuracy, a SRY cheek swab test is a simple non-invasive screening test that can flag individuals for further investigation. World Athletics have just implemented this test, stating it is “a highly accurate proxy for biological sex”.[1] A positive result in this screening test could be combined with a finger prick test for testosterone level to provide further information, and at this point we’re into methods of medical diagnosis of DSDs. About 1 in 5000 individuals will have a DSD, some of which are still unambiguously male or female (e.g. XXY Klinefelter syndrome), and some of which are almost unique individuals that defy categorization.

At this point, it is popular to seize on those rare individuals and declare “aha! So sex isn’t binary then! So it must be a spectrum!”, and while this is surely well-intentioned, it is scientifically illiterate.[2] I suspect part of the confusion is interpreting “binary” as a mathematical Boolean value (where exceptions cannot, by definition, exist) rather than as a scientific classification, where exceptions can and do exist and “prove the rule”.

[0] https://www.sciencedirect.com/science/article/pii/S004269892...

[1] https://www.bbc.com/sport/athletics/articles/cj91dr17d1no.am...

[2] https://richarddawkins.com/articles/article/race-is-a-spectr...

So the SRY cheek swab test that the IOC ruled ineffective before the 2000 Olympics is what you think is accurate? Interesting.

It is a screening test, not a diagnostic test. False positives are possible, but so are followup tests for those cases.

I guess it doesn't answer my question then.

The question was:

>What tests with what results would conclusively show which individuals went down which pathway?

You've managed to provide 0 tests that conclusively answer the question.

If your target level of accuracy is 100%, there is probably no medical test that can show anything.

Did you know there is no conclusive test for Alzheimer’s, IBS, migraines, and dozens more physical conditions, nor for any psychiatric condition? Do you think these aren’t real, or that they cannot be discerned to a useful degree of accuracy?

Well that's why when the law is concerned, it usually defers identification to a trained professional (e.g. as determined by a doctor ).

Besides that, there are things you can determine with certainty: The presence of a substance in blood for example

A physical examination by a doctor, possibly augmented by imaging, is an excellent way to determine sex if previous observations and tests have been ambiguous. This is rarely a great difficulty, but when it is, it's how DSDs get diagnosed.

So which tests with which results would you rely on?

Which bit are you having difficulty understanding? Make trivial observations if you want moderate accuracy (~99%), use a cheek swab or genetic test if you want greater accuracy, consult a doctor if you are still unsure.

Which part of my question are you having difficulty understanding? If this is so important and accurate surely you can name and explain the important and accurate tests, and their results. Maybe it isn't as simple as you say?

Why should the simplicity of the definition (which, by the way, is what sex means in mammals generally, not just in humans) mean that the testing has to be simple in 100% of cases? I’ve already described cases where it isn’t. That doesn’t change the definition.

Do you think natural phenomena don’t exist or can’t be useful unless there is a simple test to grant you the details?

I think there are tests that intelligent people can describe which demonstrate the phenomena exists. That's what science is.

I think my answer was larger than the box you drew for it, and now you’ve sealioned yourself into a very weird corner where you seem to think the existence of male and female developmental pathways is somehow negated by edge cases.

Why do you suppose such a test could even exist?

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