Clownfish. Sequential hermaphrodites. How to recognise the female: she makes large gametes.
Anglerfish. Extreme dimorphism. How to recognise the female: she makes large gametes.
Seahorses. Female fucks around while male carries babies. How to recognise the female: she makes large gametes.
Birds. Non-XY genetic determination. How to recognise the female: she makes large gametes.
Crocodiles. Sex determined by environmental temperature during development. How to recognise the female: she makes large gametes.
Platypus. Five pairs of sex chromosomes. X1X1X2X2X3X3X4X4X5X5 (female) and X1Y1X2Y2.... (male), where X3 and X5 look more like a bird (non X) than a mammal. How to recognise the female: she makes large gametes.
Hyena. Females have pseudo-penis which she internalises during mating. How to recognise the female: she makes large gametes.
Lily. Hermaphrodites. How to recognise the female part: it makes large gametes.
Flatworms. Hermaphrodites. They penis fence to determine which takes the male role. Most of the time, no-one wins and they each, perhaps dejectedly, spaff (😉) over the other. How to recognise the female part: it makes large gametes.
Bees. Males are missing an entire genome copy. How to recognise the female: she makes large gametes.
Asparagus. No sense of sexed self and no plausible mechanism for social construction of gender. How to recognise the female: she makes large gametes.
Tuatara. Sex determination so extremely temperature sensitive that climate change is causing them to be all male. How to recognise the male: he makes small gametes. He can also be seen looking annoyed at enforced incel status.
I’m pinning this. Please add requests. Also, any examples you see touted as an argument against sex. What was the strawberry one?
Peafowl. Sexual selection gone mental. How to recognise the female: she makes large gametes. And she’s not a massive freaking showoff, like this fella...
Mushrooms. Delicious. How to recognise the female: there are no females (‘there is only Zuul’). ‘Female’ and ‘male’ are predicated on two and only two differential gametes, and fungi don’t have them thingies, settling instead for equivalent gametes labelled +/-, or A/B, or yawn.
Fun fact (not really): the truly unique structure of the female hyena reproductive system, whereby she is sole arbiter of when to allow intercourse, suggests that female hyenas cannot be raped.
Straw-not technically a berry-berries. Delicious hermaphrodites. Genetic sex determination is polygenic and may reasonably be described as a (limited) spectrum. How to recognise the female part: it makes large gametes.
Head lice. Annoying buggers. The female transmits chromosomes she inherited from either her mum or dad; the male *only* transmits chromosomes he inherited from his mum. How to recognise the female: she makes large gametes.

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More from @FondOfBeetles

Feb 21
This is your regular reminder that I am not an entomologist and I do not study beetles.

My handle is derived from a quote about creationism and I research human genetics and genetic disorders, including one that kills males.

Here is a motor neuron I grew in a dish. Image
I do not study cool things like…

Jewel beetles. Studies of their iridescence (like liquid crystals) has helped paint chemists. It’s also surprisingly good camo (expt: attach bright or dull wings to mealworms and see which get eaten by birds…). Image
Dung beetles. They roll crap around all day. Their immune systems are a source of some interest. Image
Read 12 tweets
Feb 1
@RealTayChaTLC Right, let's do this.

Sex is *observed* at birth by “reading” external genitalia, which is a remarkably sensitive marker of sex. Sex is also now routinely observed in utero, again by “reading” external genitalia and, increasingly, by DNA analysis.
@RealTayChaTLC The definition of female is: of or denoting the sex that can produce large gametes.

This not a matter of *observation*, this is a matter of *definition*.
@RealTayChaTLC Very few animals and no plants menstruate, yet females exist across almost all complex life.
We do not become men at menopause. We certainly don’t “revert” to men, which implies we were men at some point before menopause. Maybe you think we are men before menstruation?
Read 7 tweets
Jan 25
Across the natural world, male and female are defined by reproductive function, describing the contribution of small gametes (like sperm) or large gametes (like ova), respectively, to the next generation.
In healthy humans, there are two anatomical body types, each corresponding to one of the two reproductive functions. That is, in humans, there are two sexes.
In utero, males and females develop sex-specific primary characteristics pertinent to function during reproduction.

Healthy male anatomy comprises testicles, internal genital structures like the vas deferens and an external penis and scrotum.
Read 9 tweets
Jan 23
Here is a graphic of changes in muscle and strength in transwomen pre- and post- testosterone suppression (12+ months), compared with baseline metrics from demographically matched females.
The original data is presented in Hilton and Lundberg, 2021 (Table 4).

My coauthor was Dr Tommy Lundberg @TLexercise

link.springer.com/article/10.100…
The graphic was created by me for a policy paper I coauthored with Professor Jon Pike @runthinkwrite and Professor Leslie Howe @usask for the Canadian think tank The MacDonald Laurier Institute.

macdonaldlaurier.ca/biology-fairne…
Read 11 tweets
Jan 19
I recently tweeted about people who think I believe humans are asparagus.

This bad faith take stems (ha ha) from an analogy I’ve used to illustrate that the phenomenon of male/female is not limited to the constructions of the human brain.
Like many plants, and like humans, (some) asparagus strains are dioecious - they exist as individuals male and individual female plants. In animals, we call this set up ‘gonochorism’.
Asparagus can reproduce via the fusion of one small and one large gamete (sometimes, they reproduce asexually).

Biological convention denotes the plant morph producing the large gamete, found in the ovules, as ‘female’.
Read 16 tweets
Jan 18
Sexual dimorphism.

Systematic differences between the two sexes of a gonochoristic species of a physical characteristic (or set thereof), not including reproductive anatomy.
Some sexually dimorphic characteristics are non-overlapping (e.g. deer antlers) while some are very overlapping (e.g. human height).

The extent of overlapping observation/measurement is irrelevant. The only requirement is a robustly-detectable difference between sexes.
Many female humans are taller than many male humans, yet the population descriptions of height in humans consistently reveal that males as a sex class are taller than their demographically-matched female peers.

Height in humans is a sexually dimorphic characteristic.
Read 11 tweets

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