> Yes, it is true, whether you like it or not.

Some people disagree:

https://www.nas.org/academic-questions/33/2/in-humans-sex-is...

Why “Intersex” Conditions Do Not Invalidate the Sex Binary

But what about “intersex” individuals? Unfortunately, confusion and misunderstanding reign when it comes to their existence. Humans are indeed born with a variety of “intersex” conditions at low frequency, but that does not mean that these conditions are part of normal healthy variation. Humans are also born with a great variety of devastating congenital deformities and diseases, and if alien exozoologists were to write a description of Homo sapiens based on extensive observations of the population, such a description would never feature, for example, anencephaly, and neither would it include anything else but binary sex.

Extremely deleterious phenotypes, especially when their fitness is invariant with respect to environmental conditions, cannot be part of that description, as they are by definition actively eliminated from the population. The mathematics of natural selection is remorseless. For the human population, even an allele with an initial frequency as low as 0.01 and selection coefficient s = 0.05 is nearly ensured fixation. On the other hand, that should not be taken to mean that natural selection is all powerful. First, even if an allele is strongly deleterious, its frequency will not be zero, as it is constantly reintroduced by mutations at some rate µ. Second, alleles with small selective (dis)advantages are not ensured fixation. Genetic drift can lead to fixation of alleles with small selective coefficients irrespective of their effects, as long as s < ~1/Ne (Ne is the effective population size).

Therefore we cannot expect “perfection” from biological processes. Imagine that a biochemical reaction runs with a given accuracy in a finite population. The selective advantage of mutations improving its accuracy will generally be at most the fractional improvement that they confer. Thus it is not possible for selection to push the system towards absolute perfection as further fractional improvements are “invisible” to it if smaller than the selection barrier ~1/Ne. Errors are thus expected to occur everywhere, and indeed they do. This is why important genes get mutated, developmental processes get disrupted, and the results are newborns with very low fitness.

These facts bear on how we are to think about “intersex”' people. The great diversity of such conditions cannot be explored here in detail. These include Androgen Insensitivity Syndrome (feminization of males due to androgen receptor mutations), Klinefelter's syndrome (47,XXY karyotype), XX male syndrome (46, XX “males” due to translocation of the master regulator SRY to the X), Turner's syndrome (45,X0) and many others.

These conditions present with a variety of phenotypes intermediate between typical male and female features, but they have one crucial commonality—individuals afflicted are almost invariably sterile;20 on the few occasions where fertility is possible, the phenotypes are mild and it is hard to even call them “intersex.” Their evolutionary fitness is therefore as negative as fitness could possibly be short of being stillborn (s = -1 for sterile individuals). Importantly, these fitness reductions are invariant to environmental variables. It is possible for a condition that is a debilitating disease under some circumstances to be beneficial under others (e.g. sickle-cell anemia and malaria). But this does not apply to the inability to produce viable gametes which makes one unable to reproduce under all circumstances.

All “intersex” conditions, when examined, clearly arise from single-gene mutations or chromosomal aberrations on a genetic background that would have indisputably been producing male or female gametes had these mutations not occurred, and, rarely, due to chimerism (i.e. individuals made up of both male and female cells). True hermaphrodites possessing both sets of functional gonads and genitalia have never been observed in Homo sapiens.

Therefore the “intersex” argument against the sex binary is simply not valid. Intersex individuals exist only because of continuous de novo reintroduction of the relevant mutations in the population, recessive genes becoming unmasked, or disruptions of normal embryonic development.

Sex in mammals is on a fundamental level binary and immutable, and claims that “intersex'” individuals disprove that can only be made in the absence of any consideration of the biological nature of humans and how our evolutionary history has shaped our biology. Which brings us to the most worrying aspect of the widespread adoption of such denial

This person is not alone.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10265381/

https://pmc.ncbi.nlm.nih.gov/articles/PMC5824932/

I know there is a ongoing social debate about this, and there are people withing the field who disagrees. So it's not like you are showing me anything I haven't already seen.

The idea that there is a consensus is not accurate. There are people who disagree and they have been writing about it.

Expect to see more.

404. But have you heard the term "bimodal distribution"?

I'm sorry but the text you quoted is nonsense. Alien exozoologists could very well write about Homo sapiens "rarely they are born without brains, and die quickly." They would be correct to do so. However, this is quite a minute and usually irrelevant feature of the species. If they go into enough detail, they would write it.

There are more transgender people born than anencephalic people (... if they can even be called that).

And sterile people aren't non-people. They are people, so a very detailed description of the species would say that some people are sterile, sometimes because they are intersex.

> All “intersex” conditions, when examined, clearly arise from single-gene mutations or chromosomal aberrations on a genetic background that would have indisputably been producing male or female gametes had these mutations not occurred

so what? this is meaningless. This is searching for plausible sounding arguments to justify a desired conclusion.

> Therefore the “intersex” argument against the sex binary is simply not valid. Intersex individuals exist

therefore sex is not completely binary. It doesn't matter why. You are reaching for plausible sounding arguments, that on closer inspection still make no sense. Some people are male, some are female, and some are neither, therefore, it is not true that all people are male or female. QED. This is very basic logic. Defying very basic logic is nonsense. You might as well argue that 1+1=3, we just haven't seen it yet.

> Sex in mammals is on a fundamental level binary and immutable

What would it take to disprove this for you? I have a feeling that if someone designed a gender change ray that could convert a human male into a human female, in all aspects including cellular genetics, genitals, and brain structure, you'd still say sex was immutable and the ray didn't really do that.

> claims that “intersex'” individuals disprove that can only be made in the absence of any consideration of the biological nature of humans

Claims that sex is strictly binary, rather than bimodal, can only be made while looking the emperor in the eye and saying his clothes are gorgeous. Intersex people exist, and they are not male or female - that's the definition. But you don't want to hear it, and would rather pretend they somehow don't count. That's the denial here.

Alternatively, perhaps you believe that sex is a property that is not shared by all people. That is, perhaps you believe that some people do not have a sex. Is this the case?

Keep in mind: just because something is on pubmed, doesn't make it true. "Trust the science" is bullshit, right?