Differences in Sex Development (aka "intersex")

[Elaedith]

Good stuff.

Here is something that really stuck out to me as someone who once trained in statistics: It occurs to me just now that we could conceivably choose a variable worth graphing out, e.g. number of viable gametes produced per month.

For what purpose?

It would produce a clear distinction between adult females and most adult males (those who are not infertile) if plotted on the same axis.

It still wouldn't be plotting 'maleness/femaleness' because males who produce more gametes are not more male than those with a lower sperm count.

 

[d4m10n]

For what purpose?

I think you answered this question in your next sentence.

On an appropriate logarithmic scale, we would see one cluster around zero (individuals who are subject of this thread), one cluster around one, and another cluster way up the line.

 

[Emily's Cat]

I think you answered this question in your next sentence.

On an appropriate logarithmic scale, we would see one cluster around zero (individuals who are subject of this thread), one cluster around one, and another cluster way up the line.

Translate this, please? 0, 1, and a lot? Who do you think falls into those categories?

 

[d4m10n]

Translate this, please? 0, 1, and a lot? Who do you think falls into those categories?

Adult females of reproductive age will tend to produce around one viable gamete per month.

Adult males of repoductive age produce something at least in the billions.

Intersex individuals of reproductive age who are not fertile in either of the above senses will cluster around zero viable gametes per month.

 

[Rolfe]

Lots of people of both sexes who are not intersex and who are of normal reproductive age will post either zero or (in the case of males) a low-ish number of viable gametes due to infertility or sub-fertility. Intersex conditions are far from the only causes of infertility or sub-fertility.

Then you have individuals of both sexes before puberty, and females post menopause. It's not that helpful for population classification when you take all that into account.

 

[d4m10n]

Lots of people of both sexes who are not intersex and who are of normal reproductive age will post either zero or (in the case of males) a low-ish number of viable gametes due to infertility or sub-fertility.

Lowish for males will still be way higher than normal for females, so there won't be any doubt which bell curve to group those individuals into.

Intersex conditions are far from the only causes of infertility or sub-fertility.

Fair point, but putting the zeroes aside we'd still a bimodal curve.

 

[Rolfe]

Yes, I suppose that's a point.

 

[theprestige]

Lowish for males will still be way higher than normal for females, so there won't be any doubt which bell curve to group those individuals into.

Fair point, but putting the zeroes aside we'd still a bimodal curve.

I know nothing about statistics, but wouldn't a binary distribution (or whatever the right technical term is) generate an essentially bimodal curve?

 

[Elaedith]

I know nothing about statistics, but wouldn't a binary distribution (or whatever the right technical term is) generate an essentially bimodal curve?

A binary variable is a categorical variable with two categories so it doesn't generate a curve. A categorical variable with more than two categories can technically have two modes but does not generate a meaningful curve if there is no logical order to the categories. Characteristics associated with sex that can be plotted on a continuous distribution will show bimodal characteristics because these characteristics are associated with an underlying variable that is binary.

 

[Emily's Cat]

Adult females of reproductive age will tend to produce around one viable gamete per month.

Adult males of repoductive age produce something at least in the billions.

Intersex individuals of reproductive age who are not fertile in either of the above senses will cluster around zero viable gametes per month.

Females don't produce an egg a month, we release an egg a month. All of our eggs are produced during fetal development.

Males begin producing sperm with puberty, and have none prior to that.

 

[Emily's Cat]

Fair point, but putting the zeroes aside we'd still a bimodal curve.

You'd see one curve, and a spike. Because it isn't one population, it's two populations stuck on the same graph.

 

[Emily's Cat]

I know nothing about statistics, but wouldn't a binary distribution (or whatever the right technical term is) generate an essentially bimodal curve?

Binary distribution creates two spikes. It's a yes/no distribution, so what you end up with is a visual representation of the probability of a yes versus a no.

Binary is a categorical distribution. You can only get a bimodal result from an ordinal or continuous distribution. And in 99.99% of cases, when you get a bimodal result, it's an indicator to go look at your data set, because you've probably got two distinct populations based on a characteristic not captured in your data.

For example, if you were plotting the weight of cats and ended up with two modes, it's probably worth noting that your category of cat contains both domestic pets and wild lynx - two distinct populations, each with it's own independent distribution that overlap a bit.

 

[Emily's Cat]

A binary variable is a categorical variable with two categories so it doesn't generate a curve. A categorical variable with more than two categories can technically have two modes but does not generate a meaningful curve if there is no logical order to the categories. Characteristics associated with sex that can be plotted on a continuous distribution will show bimodal characteristics because these characteristics are associated with an underlying variable that is binary.

Exactly. Although with categorical variables with more than two categories, you'll only get something that looks like two modes depending on how you order them to plot.

 

[d4m10n]

Females don't produce an egg a month, we release an egg a month.

Right, but when I said "viable gamete" I meant one that is prepared for the process of fusion with an opposite-sexed gamete. In females, that's a secondary oocyte.

You'd see one curve, and a spike.

I don't think so. We'd see one cluster of data peaking around one gamete per month, and a much more spread out curve peaking somewhere in the billions. You'd need a log scale on the x-axis (average number of gametes per month) to see both curves at the same time.

 

[Elaedith]

Exactly. Although with categorical variables with more than two categories, you'll only get something that looks like two modes depending on how you order them to plot.

I wasn't thinking just about plotting. A mode is just the most frequently occurring value, so technically a categorical variable can have a mode or two modes if two values are much more frequent than the others, but the concept of having two modes doesn't have much use when you are not able to plot a frequency distribution.

For example, Jerry Coyne stated:
'To be a bit more precise, biological sex in humans is bimodal: if you do a frequency plot with “sex” on the X axis and “frequency of individuals conforming to that sex” on the Y axis, you get a huge peak at “male”, another huge peak at “female”, and then a few tiny blips in between that conform to hermaphrodites or intersexes.'

I don't agree with his characterisation of 'hermaphrodites or intersexes' being 'in between'. However, he is saying that sex is essentially binary for practical purposes and treating it as a categorical variable. What Novella and others are plotting is clearly a continuous distribution with two modes, but without specifying what is on the X axis. So even if Coyne was correct it doesn't have anything to do with the ideologically-motivated nonsense Novella is promoting.

 

[theprestige]

To me, "in between" connotes a continuum of healthy developmental paths. What we actually get "in between" is an undesirable crossing of characteristics drawn from two binary development paths, neither of which develops properly to fruition. Though one or the other may develop enough to be at least minimally functional.

 

[Rolfe]

I don't think that's so as regards sex. There is a ridiculous graph in circulation which claims a bimodal distribution, but there is no label on the x-axis. It could easily be height, or weight, or grip strength, or even hair length. But it's being presented as if the axis was in some way "essence of sex".

"Intersex" just doesn't work that way. It's a misnomer. It's a catch-all term for people who are either male or female but have some anomaly in their male or female sex organs. It's not that they have bits of the sex organs of the opposite sex. (Even the rare-as-hen's-teeth ovotestis condition is basically either male or female but with some vestigial developmental material that went down the wrong path.)

 

[Emily's Cat]

To me, "in between" connotes a continuum of healthy developmental paths. What we actually get "in between" is an undesirable crossing of characteristics drawn from two binary development paths, neither of which develops properly to fruition. Though one or the other may develop enough to be at least minimally functional.

The overhwelming majority of DSDs don't have any ambiguity about sex. Even several of the conditions that can result in atypical genital formation aren't ambiguous about sex. 5-ard, for example, frequently presents with a very small penis and divided scrotum at birth, which can result in an incorrect identification of sex in less developed countries. But at puberty, they go through a typical male development, frequently resulting in an elongated penis, and their testes frequently produce sperm.

There are extraordinarily few cases where there really is ambiguity about sex. Those involved ovotestes, where the gamete-producing tissue was interrupted during development. In most cases, there's only one ovotestis, and the other will be recognizably either an ovary or a testicle. In the even more rare cases where both are ovotestes the designation of male or female is made on the basis of the rest of the organs, and whether they are predominantly Mullerian or Wolffian. So, ferinstance, if everything is confused, but there's a prostate - male. If everything is confused, but there is a rudimentary uterus, female.

 

[Steersman]

Females don't produce an egg a month, we release an egg a month. All of our eggs are produced during fetal development.

Males begin producing sperm with puberty, and have none prior to that.

I wouldn't want to be seen as trying to tell my grandmother how to suck eggs (see the Wikipedia article thereon) ..., but the Wikipedia article on oogenesis emphasizes that XXers are only born with "ootids" that don't mature into ova that can actually be used in reproduction until ovulation - which of course can't take place until after puberty:

Oogenesis starts with the process of developing primary oocytes, which occurs via the transformation of oogonia into primary oocytes, a process called oocytogenesis. .... Both polar bodies disintegrate at the end of Meiosis II, leaving only the ootid, which then eventually undergoes maturation into a mature ovum.

Girls are born with 1-2 million of those "primary oocytes", but only some 500 mature into actual ova that can actually be used in reproduction. A woman only PRODUCES (present tense indefinite) some 500 ova from puberty to menopause.

 

[Steersman]

... because that person looks female on the outside ....

I wonder what your definition is for "female" and for "male". Whether you would subscribe to the standard biological definitions for both.

More specifically, see the Glossary in an article (Gamete competition, gamete limitation, and the evolution of the two sexes) at the Oxford Journal of Molecular Human Reproduction by biologists Parker and Lehtonen, definitions that are pretty much standard in many dictionaries (Lexico, Google/OED) and encyclopedias (Wikipedia):

"Female: Biologically, the female sex is defined as the adult phenotype that produces [present tense indefinite] the larger gametes in anisogamous systems.

Male: Biologically, the male sex is defined as the adult phenotype that produces [present tense indefinite] the smaller gametes in anisogamous systems."

Don't think it's really possible to decide who is in which category, which people are "ambiguous", if we haven't FIRST defined what we mean by the terms. Like hunting the snark otherwise ...