On the existence of females

This post has been adapted from a twitter thread.

Some time ago, I lived in a house that had a number of peafowl living in the garden. (Long story). They used to come in the house and steal my cats’ food.

We can tell this is a female peafowl – a peahen – because she is busy feeding the children and not squawking and strutting around outside with show-off feathers. But importantly, she is the one that laid the eggs. The eggs are the important thing.

The cat is a male cat – Dylan – he is male because he is fat and lazy and does not produce eggs. His sister, Lottie, is a female because she developed an anatomy that supports egg production. She remains a female even though she was spayed.

When we say Lottie is female and the peahen is female we mean the same thing – a reference to eggs. And that link and common meaning is rooted in deep time. The cat and the bird (and us) share a common ancestor – a common mother who also produced eggs.

That last common mother of all of us looked a little like this…

She was an Amniote – a lizard-like creature that had evolved on a different path than the amphibians with an evolved trick of laying eggs out of water.

Our last common mother laid a clutch of eggs – perhaps under some fallen logs, and they hatched to form little baby amniotes. But that family line then diverged, with one side resulting in Synapsida – the cats, and the apes that open the tins for them…

… and on the other side, the Sauropsida – the lizards, crocodiles and avian dinosaurs we call peafowl. Some of the Synapsida evolved an additional neat trick of allowing the eggs to develop internally rather than having to go through the bother of building a nest.

And each female here can trace their ancestry back along an unbroken converging chain of mothers and daughters across 300 million years to that last shared mother – the Amniote lizard-like thing. Males have been along for the ride too – sometimes providing the sperm.

Each daughter looked pretty much like her mother. But over that vast expanse of time, those creatures changed and adapted to a changing world to produce all the species of mammals, reptiles and birds you see today.

And we can keep tracing that line of mothers and daughters back about 1,000,000,000 years to a multicellular organism that started producing different sized diploid sex cells. We do not know quite why, but sexually reproducing organisms that shared genetic material started adopting a system where each sex cell involved in sharing had to be different in size. Large sex cells became eggs and small ones became sperm. That first large sex cell producer was the first female. A billion or more years ago.

That asymmetrical requirement for a small and large sex cell to combine has been remarkably conserved across deep time. That binary asymmetry is what leads to the development of two organism types – males and females. No other sex cell type has emerged in our shared lineage.

Evolution has created two development paths for organisms like our cats and peafowl that allow each organism to develop with respect to each asymmetrical gamete type. Our sex characteristics though vary enormously from the absurd tails of peacocks to the milk glands of my cat.

How each sex is determined has become enormously complex, with mammals – XX/XY and SRY gene mechanism – to the ZW/ZZ mechanism in birds – which I understand is still not fully understood. Some of our cousins use environmental switches, like crocodiles.

And of course those male and female development paths are absurdly complex and it is remarkable that they only go wrong very rarely to produce development conditions – what are sometimes called ‘intersex conditions’. These are not new sex classes though as there is no new gamete.

What is strange is that in the past 10 years, an idea has evolved among the cat-food tin opening apes that sex is not real, it is an arbitrary construct, it is ill-defined and difficult to talk objectively about. It is a spectrum of possibilities rather than these two categories.

This is not an idea you will find in the biology peer-reviewed literature where sex is universally described as above – a category based on gamete types. The idea is used to undermine the ability of females to describe their unique position in life & their associated experiences.

It is a political and social idea that impacts females and their rights to define themselves as a material class. Biology rejects this absurd idea of the arbitrariness of sex. We need biologists to speak up and to say that rather than leaving it up to children’s fantasy authors.

24 Comments on On the existence of females

  1. To look at, I am patently male. No confusion. Biologically, I am patently male. My singing voice however is countertenor. It is all the people who accept “intersex” without question who have a problem with that. Agendas, much?

  2. Thank you for posting this. The issue of what to name people born as men but wishing to be referred as female has largely been a ‘debate’ between (some) feminists and trans activitists. It is good to see men wade into the debate as well.

  3. Nicely done, but this seems a bit like complaining that some food vendors are using the term “organic” wrongly, and calling on chemists to rise up and correct them.

    A lot of friction in the trans debate/argument does seem to come from a lack of good words to describe the variety of intersex conditions, especially since there’s a resistance to medicalising personal perceptions of gender identity. The lack of good words leads to feelings of trespass, and advocates applying extrapolative logic to miss the point on both sides.

    So yes, it’s a political issue, primarily connected to issues of rights and equalities above biology. (Psychology, if anything, seems the most relevant science.) Bringing gametes into it feels like a category error.

  4. The author is simply stating the case that sex is real, that it is dimorphic or binary, and that one sex category cannot become the other – and he has done that brilliantly.
    The friction you refer to is down to the insistence by many of those who promote transgenderism that all of the above is not real, at largely the cost of the female sex class.
    The women, and men, who are opposing self ID and the promotion that males can become ‘women’ and therefore female, with all of the rights to the protections afforded to females based on their biology, are not being anti-trans or anti-intersex, just pro-reality.
    I agree about the terminology, but this is a lack of consensus of good words; there are plenty of scientific terms to describe intersex conditions – it’s just that some people want to reject these because they undermine their claim that sex is a ‘spectrum’.
    When we find or create something new, we give it a new name, one that distinguishes it from an already existing word that has specific meaning –
    woman: adult human female
    female: the sex that can produce eggs

    • You might want to check your reality – in ours, women can’t produce eggs. Females are born with them, but after birth no more produced. And of course if the ovaries are removed for whatever reason, that doesn’t stop the person being female. Or does it?
      So maybe a slight tweak to your definition might be needed, say “female – the sex that was probably born with eggs but may or may not have any”. But that doesn’t really define anything, so we will just have to create some new words for women in or after the menopause and after ovarian surgery, etc. And males and females who have had gender reassignment. And are there any words for people who are an affront to our reality?
      Suggestions, anyone?

      • Sorry you find a dictionary definition so offensive. You will find that a female foetus is still female even in the womb… and females ‘can’, not necessarily ‘do’, produce eggs

      • I don’t find it offensive, I just find it useless as a scientific definition. In exactly the same way that defining humans as ‘mammals that can survive without breathing for 9 months’ – it’s equally true, but both happen before birth and in the ‘real’ world we tend to use definitions that apply currently rather than only in gestation.
        A scientific definition needs to hold true in all cases, rather than in a limited range that is not defined in the definition.

  5. I spent a summer on a farm with a male and female peafowls. Three peachicks hatched and they could fly short hops almost as soon as their wings dried. It distressed the peahen if they flew over the low fence put up to contain them.
    They are noise dirty birds, but beautiful to see.

  6. “This is not an idea you will find in the biology peer-reviewed literature…” Give it time. We seemed to be living under populist mob-rule currently, rational debate and contrary opinion is regarded as attack and must be silenced. How long do you think it will be before biology texts feel contrained to refer to “people who menstruate”? I’m with Ms Rowling all the way, the attacks on her are shameful but it seems mainstream voices are becoming increasingly marginalised by the sheer volume of activists – god help us.

    Very sweet pictures by the way.

    Thanks for the post,


  7. I wouldn’t say that intersex conditions occur “very” rarely, occurring as they do in humans at a rate somewhere between 1 in 50 and 1 in 100.

    I know a person with such a condition, as do probably all of you, though perhaps you don’t know it.

  8. Who is defining “intersex conditions?” It is a lucrative racket to devise ever more inclusive definitions of “conditions” and “problems” and then claim to be a professional who demands the authority to treat them. I am allergic to cod roe, is that a “condition” which needs to be treated?

    • Allergy to finned fish is a frequent cause of anaphylaxis, a potentially life-threatening allergic reaction that appears quickly, impairs breathing and can send the body into shock. Would you like to do a little more background reading about intersex conditions and then get back to us?

  9. I said cod roe (which I simply avoid eating) not tinned fish (which I have no problem with, and eat regularly). You have demonstrated my point. When a medical person with lower standards than yourself has knowledge of a characteristic (such as those associated with intersex conditions, like the single X chromosome – reference Dr. Richard Raskind), they then elevate this into a manifestation of a “condition” and go looking for it everywhere, dragging any characteristic which has the vaguest similarity to the original one into the definition of the “condition”. This then becomes a “problem” for which they are the “solution”. On the contrary, they are the problem, and the medical profession should recognise this, just as the fact that child abusers want to work in children’s homes is now recognised, but once was not.

    As you implied, the issue of “gender identification” is not about science but agendas, which it should never be.

  10. We need to distinguish between ‘intersex’, a physical/genetic condition, and ‘gender dysphoria’, a psychosexual condition (see https://www.tandfonline.com/doi/full/10.3109/09540261.2015.1115754?src=recsys
    “Gender dysphoria (GD) in childhood is a complex phenomenon characterized by clinically significant distress due to the incongruence between assigned gender at birth and experienced gender”)

    I have no doubt that some individuals in a body genetically and physically of one sex genuinely identify as the opposite sex and may want or need to physically transition as a way to manage this and help their mental well-being.

    I have two concerns however, which apparently it is not permissable to discuss in the current climate. One is about pressure put on children who may feel they ‘don’t fit in’ to do something dramatic (i.e. begin to transition) in an attempt to address feelings that may actually be unrelated to sexuality – depression, loneliness and so on. This pressure may come from peers, social media or so-called help groups who have invested in sex or gender issues and are resistant to discussion of other routes to a solution.

    My second concern is with the concept of “self-identification” – if someone is allowed to self-identify as a member of the opposite sex without any reference to independent counselling, or psychiatric or medical advice then how do we know they are genuine? Particularly in the case of men self-identifying as female – should they have access to female lavatories, changing-rooms and so on simply on this basis?

  11. One of the problems with the diagnosis of gender dysphoria – particularly in children – is the diagnostic criteria:

    Criteria for the diagnosis of gender dysphoria in children and adolescents

    A strong desire to be of the other gender or an insistence that one is the other gender.

    A strong preference for wearing clothes typical of the opposite gender.

    A strong preference for cross-gender roles in make-believe play or fantasy play.

    A strong preference for the toys, games or activities stereotypically used or engaged in by the other gender.

    A strong preference for playmates of the other gender.

    A strong rejection of toys, games and activities typical of one’s assigned gender.

    A strong dislike of one’s sexual anatomy.

    A strong desire for the physical sex characteristics that match one’s experienced gender.[1]

    These are the criteria used at the Tavistock and Portman DIDS clinic. This is regressive nonsense.

    The criteria used for adults is essentially the same except for the mention of toys:

    Criteria for the diagnosis of gender dysphoria in adults

    A marked incongruence between one’s experienced/expressed gender and primary and/or secondary sex characteristics.

    A strong desire to be rid of one’s primary and/or secondary sex characteristics.

    A strong desire for the primary and/or secondary sex characteristics of the other gender.

    A strong desire to be of the other gender.

    A strong desire to be treated as the other gender.

    A strong conviction that one has the typical feelings and reactions of the other gender.[1]


    1. Butler, G., De Graaf, Nastasja, Wren, Bernadette, & Carmichael, Polly. (2018). Assessment and support of children and adolescents with gender dysphoria | Archives of Disease in Childhood. Bmj, Diseases in Childhood, 103(7). Retrieved from https://adc.bmj.com/content/103/7/631

  12. This was entirely my point. These are characteristics, not necessarily “conditions”, but if you have a big enough ego, and a similarly great contempt for the rest of humanity, they become excuses for controlling and damaging other individuals. There is no science involved.

  13. The difference is that being male or female is not regarded as a “condition” requiring medical intervention, merely a characteristic. An intersex “condition” gives others the license to make medical “interventions” which have no basis in science and all in the agendas and egos of those who intervene. We can all see the huge profits that would be made by a few, at no benefit to the patients or the community, if being “male” or “female” was regarded as a condition needing treatment – a mindset not unknown to those of us married to the opposite sex!

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