Emma Hilton Profile picture
Aug 25, 2022 15 tweets 7 min read Read on X
@PopSci I've read your article. Here are my thoughts.

First, this is your key. Image
@PopSci Gonochorists like humans. Image
@PopSci Protandrous sequential hermaphrodites like clownfish. Image
@PopSci Protogynous sequential hermaphrodites like wrasse. Image
@PopSci Simultaneous hermaphrodites with ovotestis like snails. Image
@PopSci Simultaneous hermaphrodites with separate gonads like worms. Image
@PopSci Occasional gynandromorphy like butterflies. Image
@PopSci Plants with male and female flowers on the same plant like corn. Image
@PopSci Plants with male and female flowers on separate plants like asparagus. Image
@PopSci Plants with perfect flowers (male and female in same flower) like lilies. Image
@PopSci Plants with male and female flowers on the same plant that have developed mechanisms to avoid self-pollination like avocados. Image
@PopSci Plants with a diverse array of sex allocation like you tomato species. Image
@PopSci Nothing you've claimed in your "article" can get away from the fact that there are only two symbols on this thread. Because there are two sexes.
@PopSci And of course, one of the diagrams had to be wrong. The male/female symbols should be switched here, to indicate female>male.

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More from @FondOfBeetles

Mar 27
People with 5ARD are male, not female

In defence of Semenya et al, many argue:
1. athletes with 5ARD are female;
2. features associated with 5ARD are normal female variation;
3. these athletes should be included in female sports.

The first claim is incoherent.Image
To understand 5ARD, let's look at healthy reproductive development.

Both male and female development are well-understood. Image
Male development
1. Y chromosome carrying functional SRY that directs testes development
2. testes produce hormones, notably testosterone (T)
3. T first drives male internal genitalia development
4. T>DHT conversion drives male external genital development
Read 20 tweets
Mar 26
“Sex screening in athletes is racist!”

Why? Really struggling with this.

In our recent paper (cited by World Athletics @sebcoe) calling for the reintroduction of sex screening in the female category, we make it very clear that this type of screening must be:

1. Cohort-wide | performed in all athletes wishing to enter the female category, regardless of skin colour, religion, nationality etc.

2. Early | to protect privacy and dignity, and avoid athletes being front-page news.

With these parameters in mind, the sex screen itself cannot be considered “racist”.

onlinelibrary.wiley.com/doi/epdf/10.11…
Citing historic ethical issues won’t wash. We all acknowledge these. Early, cohort-wide screening will avoid the failures of the past.

So the cry of “racism” must be aimed elsewhere, presumably anchored on the premise that previous targeted screening (which is precisely what I and others advocate against) brought multiple black athletes and very few white athletes to our front pages.
Now, let’s grant that and think about what that means.

The charge against me and others is that we are “policing sex” in a way that excludes black women (when measured against “white femininity”).

My friends, I am here to tell you that I - an adult human female with white skin - am precisely the same quality and amount of female as any adult human female with black skin.

Black women aren’t female by some weird voodoo. They are women in precisely the same way as white women are women.

In fact, it starts to look a bit racist on your part to suggest that black women aren’t women in the same way as white women are women.

Ironic, huh?
Read 8 tweets
Mar 25
In sport, we are interested in the effects of male or female development on the body, not the booty.

The category boundary between males and females is male-pattern androgenisation - having testes that make testosterone (T) and a functional T response.Image
Disorders of sex development (DSDs) affect reproductive development, and sometimes challenge legal and social sex classification.

5ARD, for example, means a male baby doesn't make the hormone required for penis development. The baby may be misclassified as female at birth. Image
But there is no evidence that having 5ARD means you don't go through normal male "rest-of-body" development, and this gives performance advantages in sport. Image
Read 4 tweets
Jan 26
On “we all start as females” (by request).

At the level of anatomy, “female” describes a particular reproductive system - eggs in ovaries, oviducts, uterus, cervix, vagina and vulva.
This reproductive system begins to differentiate at around six weeks post-fertilisation, when the embryonic gonads - two balls of cells clumped in your pelvic area - turn into ovaries and not testes.
The ongoing development of internal and external genitalia follows this gonadal differentiation into ovaries.

This is what is meant by “organisation” - the coordinated, sequential development of multiple tissues that have evolved around a given reproductive function.
Read 19 tweets
Dec 25, 2024
I ran a fairly straightforward analysis of track and field performances across junior ages in different track and field competitions.

The raw analysis looks like this for international records. Above the line is male advantage, below the line is female advantage.

This pattern its repeated across national and state-level competitions. You can see that for almost all events at all ages, boys hold advantage over girls.Image
Image
Where female advantage is detected, this is easily explained.

At 10 years old, girls grow ahead of boys, and catch up/overtake them briefly in running.

The female advantage in discus at 15-16 years old is because girls throw lighter implements.

The distance drop off as boys move to the 2 kg discus is obvious.Image
But actually, while these data are good for getting a handle on the magnitude of advantage, I came up with a slightly different question to ask of them.

With help from @johnarmstrong5, I came up with a null hypothesis: if there is no difference between boys and girls pre-puberty, the frequency of boys and girls "winning" should be around 50/50.

So I collapsed the performances as wins or losses. See below for international records, scored as wins for the boys above the line and wins for the girls below the line.Image
Image
Read 5 tweets
Dec 16, 2024
Hello @michaelshermer

Please see the following links to various papers and commentaries I and others have published on sports categories.

Please follow me (obvs 😂), @TLexercise @Scienceofsport @runthinkwrite @cathydevine56 @BrowngaGreg @MaryOConnorMD @DrMJoyner and associated scientists for academic work.

Guys, add your papers below please.
Where it all started (academically): “the muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed.”

There are a couple of letter responses linked to this too.

link.springer.com/article/10.100…
Tommy @TLexercise has worked with transgender women with an eye specifically on sports.

academic.oup.com/jcem/article/1…

onlinelibrary.wiley.com/doi/10.1111/jo…
Read 6 tweets

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