Biological sex spectrum research

[WomanAndProud]

I'm looking for peer-reviewed research into this. I'm not a biologist, but have access to almost any research. What am I looking for and who am I looking for?

And can anybody unequivocally tell me that this spectrum isn't about inter-sex people "bridging" the two official biological sexes?

I know there are people reading these boards who think we're all a bunch of backward bigots, but I'm here, I'm asking for the research that I'm seeing increasingly alluded to, but not ever directly cited. Please give it to me.

I'm seeing things about extra chromosomes etc. What is all this based on? How could someone have full male genitals but be biologically female due to chromosomes? School biology told me that's impossible.

What is the XO chromosome combination?

If you're an actual biologist (degree level or higher - PhD into biological sex would be perfect.. ) why is this untrue or why is it scientifically proven?

My understanding of biological sex is limited (or "limited") to xy/penis = male sex, xx/vulva/vagina = female sex. Why is this wrong? I'm ONLY talking about biology. Explanation of terms for a general audience would be great!

And if no peer-reviewed research or explanations turn up, I'll assume that means there aren't any.

I'm in and out of mumsnet, so I may not respond immediately, but I will be back.

Thanks in advance!

Are you looking for research which proves humans are sexually dimorphic? Or any research which suggests sex is a spectrum? Pretty much any biology textbook will provide the first. There is no proper, evid

Sorry! There is no proper, evidence-based, peer-reviewed research which shows biological sex is a spectrum.

The only way biological sexual behaviour in humans could possibly be a spectrum would be if science identified a third or fourth or twenty-fourth gamete. And after a few million years of evolution that it not going to happen. Mammals are sexually dimorphic - male and female gametes.

Intersex people are male or female with chromosome disorders, they are stages along the way.

Your question is a bit like asking for the research which proves gravity doesn’t exist or the earth is flat or the sun revolves around the moon. Some parts of our material reality just are.

By no means an expert.
X0 is Turner syndrome, I believe. All people who have Turner syndrome are female but are unable to have children (and have usually some learning needs and physical characteristics). I once worked with a little girl who had mosaic Turner syndrome (so not every cell had the missing chromosome), her non mosaic cells were XY so she "should" have been a boy I suppose. She had significant learning difficulties.

Do you just want a peer-reviewed review article explaining DSD conditions that will explain the variations? Or do you want primary research into DSDs?

That's how I interpreted your post. As above, there isn't afaik any research showing DSDs are a "sex spectrum", as they aren't.

For real concrete evidence that sex is a spectrum, would we not need humans who can create offspring without having the standard xx & xy sperm & egg combo. Without scientific intervention.

Otherwise any variation to sex is a disorder and not a normal variation. Or is it more complex than that?

I think some people can carry xx when there xy but it's in cells and genes other than the reproductive ones.

This might help.

I love your reference to 'two official sexes' as if they've been designated by the state, rather then described from biology.

I'm confused by 'this spectrum' and 'bridging', as the assumption that there is a 'sex spectrum' is question begging (assuming the answer in the contruction of the question). Rather as 'official' implies 'unofficial'.

GCSE biology told me about Turner, XYY and XXY syndromes. Also Edwards and Downs. Wikipedia will happily tell you.

I'm aware of mutations such as people who have two copies of the dax gene on their X chromosome; 2 daxes on the X beat 1 sry on the Y, so such people would be XY but biologically female. I suppose it might also be possible for the sry to somehow move itself onto the X; if so you'd have a person who had male genitals but was XX.

I meant to say! Intersex people are male or female with chromosome disorders, they NOT stages along the way.

The thread that whats linked to looks good. But what are the people you're discussing with trying to prove OP? And if they're trying to convince you of something isn't it up to them to provide the evidence?

Anyway, back to your question. Biological sex is about reproductive role. Just because some people are born with DSDs doesn't mean that men with XY chromosomes can turn into women. So even if there was any truth to the sex is a spectrum nonsense, it would be irrelevant.

There is a nature article on the matter and it actually uses the intro:

'The idea of two sexes is simplistic. Biologists now think there is a wider spectrum than that.'

www.nature.com/news/sex-redefined-1.16943

But when you read through all the examples, interesting as they are, the fact of the matter is that no matter the conditions, they can be classified as 'male' and 'female' and do not support the idea that sex is a spectrum. Some mosaicism or in vivo gene silencing experiments that somewhat impact the gonads (without swapping the organism's role in reproduction) do not change that. I guess, someone wanted to sell an article...

Mate, it's not complicated. There is no third gamete.

Humans are sexually dimorphic for the purposes of reproduction.

Developmental disorders exist. This has nothing to do with it.

Males and females are qualitatively, not quantitatively, different. They are not opposite ends of a spectrum, with intersex ‘in the middle’. To conceptualise sex like this is to say that someone with Turner syndrome is not just atypical for female (true) but is somehow more male (not remotely true). Intersex/DSDs are variations within sex class, not a gradient between the two sex classes.

Sex is a system outcome. There are many mechanisms underpinning sex differentiation and development but none of them are definitions of sex in themselves. Despite all these possible mechanistic inputs, and possible combinations in every unique individual, it’s remarkable that humans are almost always unambiguously male or female.

Sex is not just a binary, it’s a very robust binary. It collapses into a binary, even when the mechanisms go awry, or do unexpected things.

And you’ll struggle to find peer-reviewed research showing that sex is not binary because, honestly, no biologist would give the premise any serious traction. It would be like publishing ‘water is wet’.

The only people who discuss this are science journalists with agendas and idiots on Twitter.

I think you need to state clearly the claim you wish to test.

Your OP contains an amount of 'it is or isn't this or that'. What is 'it' precisely?

Who has made this claim? Where? What evidence have they offered?

It seems to me that that you're asking the active participants on this board to prove/disprove or summarise the evidence for a claim that none of them have made. A claim you think has been made by some people who may lurk on these boards - but who by their lurking nature and due to the sceptical nature of your question, are not likely to come forward and offer you their thoughts. So all a bit back to front really!

Why not find somewhere that the relevant claim has been made and ask for evidence and references from the people making it?

I do understand why you're approaching it this way and gathering knowledge from knowledgeable people makes sense but that is all you're going to get. And, it's a good place to start, educating yourself about biology. Then you'll be in a better position to assess the claims made by others critically and ask them relevant questions.

How could someone have full male genitals but be biologically female due to chromosomes? School biology told me that's impossible
It’s not logical. If someone has full male genitals (gonad/internal/external), they are NOT biologically female, even if their chromosomes would predict female. If their chromosomes look a bit unexpected, that’s interesting, exciting and worthy of furthe research. But it doesn’t make them female; it means we don’t have the full picture of how they are male.

Chromosome are a mechanism. They make sexual development happen (well, the genes they carry do), but they are not ‘sex’ in themselves.

The NHS pages are a good place to start.
School biology, like everything else in school, is a massive oversimplification.
www.nhs.uk/conditions/disorders-sex-development/

...But 'come out lurkers and explain it all to me, or I will conclude that your silence is positive proof of there being no evidence for the claim I think you've made' is disingenuous. (And very much like all those 'educate me personally on feminism, or I'll think it's crap - oh, though I will anyway, once you've gone to the trouble' posts, which at least do address the relevant audience directly).

If you’ve got all this access to data, do fucking look for the information you’re u want yourself. “Please give it to me” surely as an ADULT human “female” you’re more than fucking capable of looking for the stuff YOU want to know.

Absolutely detest this entitled attitude!

There’s no sex spectrum. There’s no gamete that is midway between a sperm and an ova. Ova do not have tails and swim in through the end of a penis like some nasty jungle river fish do.

Humans normally have 23 pairs of chromosomes, 22 pairs of autosomes which are the same in men and women, and a pair of sex chromosomes, which are XX in women and XY in men. We number the chromosomes according to size so the longest chromosome is chromosome 1, the second longest is chromosome 2, etc. We don’t number the sex chromosomes in this way because the X and Y chromosomes are different sizes, the Y being a tiny little thing with only a few dozen genes.

There are chromosomal anomalies in which it is possible to have an extra copy of one chromosome and we call these polysomies; most of these will be one extra copy, giving a third chromosome, and we call these trisomies. (There can be more than this but let’s not over complicate it). Do you know what we call someone with three copies of chromosome 1? Nothing really as they don’t exist. They are not viable. Same with chromosome 2, etc. Trisomy of chromosome 13 causes Patau syndrome, which causes severe birth defects and most children with this won’t make it to their first birthday; trisomy 18 gives you Edwards syndrome and that causes physical and mental abnormalities; again, most children with the condition won’t see out their first year.

The only autosome trisomy which will develop a viable child who can live happily and healthily into adulthood is trisomy of the relatively small 21st chromosome - and this is what causes Downs Syndrome.

Trisomies of the sex chromosomes can be less severe but they are still an abnormality; they are survivable only because the number of genes repeated is relatively small. Only one X chromosome is active in a female cell in any case so having three X chromosomes isn’t as devastating as it might have been; while the Y chromosome is a tiddler so an extra copy is neither here nor there.

But they are still abnormalities caused by duplicated chromosomes, not some third sex or midpoint of a gender spectrum. If they are part of the normal ‘sex’ spectrum then Downs, Patau and Edwards Syndromes are part of the normal ‘chromosome’ spectrum too.

For a more technical overview, try this?
emedicine.medscape.com/article/1015520-overview
Very roughly, a developing foetus will turn out female by default, unless a series of switches are flipped to turn on the development of male hormones and anatomy. In some rare circumstances, the switches don't all get flipped properly, or some get flipped when we wouldn't expect them to.
Intersex conditions are not the same as being trans. Intersex conditions are about biology. Trans identities are about personal feelings and social roles, although some trans people want medical treatment to help them fit a different social role more easily.

There are many DSD’s but one of the characteristics that unites them all is, unfortunately for those who have them, sub-fertility.

If a class of people are unable to reproduce without medical intervention they are defacto NOT a part of a spectrum of (reproductive) sex classes, because for that to be true they would need to be able to a) reproduce independently and b) reporoduce in a way that was an amalgam of the way in which humans reproduce normally. They can’t. Those that can reproduce, do so in the boring old binary way.

Male/female. Humans are sexually diamorphic.

Development is a complex interplay of factors that can and do go wrong but this is not “evidence” of a spectrum, merely that biology is not a fixed process.

I have a phd in biology, as requestd

Intersex abnormalities aren’t “evidence based”. Any peer reviewed articles will be very very old, along with the discovery of dna structure and the relationship of insulin and diabetes. If you want to read them check pubmed, but you’ll find it in any modern biology textbook.

It’s like we know down syndrome results from an extra chromosome. We don’t need peer reviews any more.

In the same way the lack of an x or y chromosome, or the presence of an extra one, will generally cause an intersex condition. XO is turners syndrome, XXY is klinefelters.

In the same way if the body doesn’t respond to male hormones, a girl will result even with a y chromosome.

Intersex individuals are a result of something going wrong with normal sexual development in utero. It isn’t a spectrum, in the same way polydactyly or an extra nipple isn’t a spectrum, it’s an anomaly.

But they are still abnormalities caused by duplicated chromosomes, not some third sex or midpoint of a gender spectrum. If they are part of the normal ‘sex’ spectrum then Downs, Patau and Edwards Syndromes are part of the normal ‘chromosome’ spectrum too.

Very, very good point!