People forget two important facts about Nature:

• Nature does not deal in binary categories.

• Nature depends on diversity for survival.

Humans, on the other hand, routinely invent and use categories to hide complexity, nuance, and diversity. These artificial categories are often binary. The creation and use of convenient but inaccurate and often misleading categories and labels has been necessary for the development of communication, social collaboration, acquiring and sharing/using information. This is non-controversial in the majority of settings: we don’t have culture wars over using words like ‘apple’ rather than having to define it each time we think or talk about it.

Imagine you want your spouse to purchase an apple but there is no word for apple, so you have to describe the specifics of what you want: a roughly round, edible fruit that grows on a tree, can be held comfortably in one’s hand, is most commonly some shade of red but sometimes green or yellow, and varies in crispness, sweetness, tartness, and firmness. We all understand that ‘apple’ is a broad term of convenience that covers a very wide range of edible fruits, and in certain specific contexts we may add modifiers to the word for increased specificity: baking apple, Granny Smith, or Cortland apple for example.

Similarly, we use ‘day’ and ‘night’ as shortcut terms that imply a binary that does not exist in Nature as day and night transition imperceptibly into each other without any natural marker. We recognize and accept that ‘day’ and ‘night’ are inaccurate and limiting categories and respond by defining multiple arbitrary delimiters: civil twilight, nautical twilight, astronomical twilight, and and similar sub-groups for day, dawn, dusk, and night. It’s just easier and more convenient to say one sleeps at night and golfs during the day.

Arbitrary categories can be a useful framework for thinking, talking about, and developing policies about gender and sex precisely because they hide the complexity and nuances of the natural world. However, just because simplistic categories are useful does not mean they are either accurate or harmless.

First, two important definitions.

Gender refers to social and cultural attributes or identities that loosely relate to the biologic traits of maleness and femaleness.

Sex is a categorization that humans use to impose an arbitrary binary division related loosely and inconsistently to biologic attributes. Sex is harder than gender to define, so hard that neither science nor the general public agree on the definition. There is chromosomal sex (XX, XY, XO, XXY, and more), gamete sex (large or small gametes), hormonal sex (levels of estrogen, testosterone), phenotypic sex (observable physical characteristics like the present of a vagina, clitoris, uterus, ovaries, testes, penis, prostate, hair pattern, voice timbre). The same way we (humans) simplify our lives at the expense of accuracy when we talk about ‘day’ and ‘night’ AS IF they were clearly defined natural binaries, we tend to use an arbitrary 3G categorization for sex: genes, gonads, genitals. In this system a 3G ‘female’ has XX 23rd chromosomes, ovaries, and a clitoris while a 3G ‘male’ has XY 23rd chromosomes, testes, and a penis. While it is understandable and useful to invent and use arbitrary and artificial categories for sex (the way we do with day/night or apple/grapefruit) it is important to bear in mind that this binary system is something humans have invented for simplicity to avoid dealing with the natural reality that there is immense diversity (which Nature loves and requires) in both sex and gender. It becomes a potentially serious problem if we convince ourselves that male/female are Natural binary categories and then build morality or public policy on this false binary.

All this is not to say that there is no such thing as a 3G female or 3G male. These are definable groupings and the majority of humans are easily sorted into these two categories. However, somewhere between 5 and 10 million Americans (and roughly 13,000 Mainers) cannot be accurately categorized with this system.

Claiming that sex is binary and that individuals are EITHER and ONLY ‘male’ or ‘female’ is no more accurate or useful than claiming there is only ‘day’ and night’ (or ‘hot’ and cold’ or ‘big’ and ‘small’). Using an invented and arbitrary binary to marginalize and exclude up to 2% of the population is problematic. If, in the interest of fairness, we are going to ban transgender girls from participating in athletics because they are outliers in the invented 3G sex categorization and might have a physiologic advantage based on hormonal and genetic factors, we should remember that BY DEFINITION 2.5% of the human population is abnormal: more than two standard deviations above the mean for height, muscle mass, testosterone levels. This means that there are 15,000 3G females in Maine who have an unfair physiologic advantage over the ‘normal’ 3G female. This number dwarfs the handful of transgender females in Maine.

I offer the following option as a thought experiment. Let’s measure height, weight, and testosterone levels of all Maine citizens before the onset of puberty and at some regular intervals thereafter. If a 3G female is above the 97.5th percentile, they must participate with and compete against 3G males. Similarly, if a 3G male is below the 97.5th percentile, they must participate with and compete against 3G females. This would serve the purpose of fairness better than using 3G categories.

(For a thorough, academic and well documented objective discussion, I recommend Sex is a Spectrum. The Limits of the Binary by Agustin Fuentes, Phd, a Professor Anthropology at Princeton University.)