The sex binary and sex spectrum can actually work together in two layers, but only if one understands how they accurately fit together.

The foundation is the sex binary, from which the spectrum of *sex characteristics* is then produced (not the other way around).

THREAD

Sex is binary because it's a mechanism that fuses two gametes of differing size to produce a new individual. Because there is only one reproductive anatomy per gamete type, there are only two sexes. This applies to all species that reproduce through anisogamy.

And this gamete type is the one trait that allows us to consistently differentiate male from female in all anisogamous species.

Because of this consistency, gamete type (and the phenotype organized around either gamete) is the most objective definition of sex in biology.

The genetic, hormonal, and environmental variation within males and within females produced from this binary system creates characteristics that form two distributions--one for males and one for females.

Sometimes traits overlap, and this is the 'sex spectrum' trans activists argue for. They argue that because there is often overlap in traits, that the categories male and female are socially constructed, and that one's sense of self should be the only relevant marker.

However, this argument only works if you detach sex characteristics from the fundamental definition of sex. Sex characteristics are the RESULT of different reproductive strategies based on the different gamete size and the required structures for releasing those two gamete types.

The trans activists dispense with the sex binary to detach sex from its evolutionary function, and once it's detached, sex characteristics (primary and secondary) have no model on which to be grounded.

Detach sex from its function and it makes sense to describe sex as a spectrum (since all you're describing is statistical variation of body types and behaviors within M and F, which exist bimodally to differing degrees).

One can hold both the system of anisogamy (the sex binary) and the sex spectrum in one's mind at the same time.

The key, however, is that the sex spectrum is simply describing a spectrum of anatomy, physiology, and behavior, not a spectrum of sex.

Since sex is a mechanism, supported by only two gametes and two gamete machineries, it is not a spectrum.

Thus, sex (male or female) is binary, and the variation of physiology and behavior within males and females exists on a spectrum.