The Remainder Structure of Sex Unfolding
A Cross-Phylum Non-Adaptive Model of Same-Sex Sexual Behavior

Writing Declaration: This paper was independently authored by Han Qin. All intellectual decisions, framework design, and editorial judgments were made by the author.

Abstract

This paper applies the Self-as-an-End (SAE) framework to biological sex determination, focusing on the subset of same-sex sexual behavior (SSB) most directly tied to sex differentiation mechanisms: exclusive same-sex partner preference (ESSP) — the stable behavioral pattern of choosing same-sex mates even when opposite-sex partners are available. The paper argues that biological sex is not a direct readout of DNA but the outcome of a physical unfolding process in which 5DD (Law of Replication) information unfolds through 7DD (Law of Differentiation) into 8DD (Law of Reproduction) structures. Physical processes necessarily carry remainder, and this remainder can manifest behaviorally as ESSP.

By comparing four sex determination systems (mammalian XY, avian ZW, reptilian temperature-dependent, and fish social-signal systems) and a cross-phylum continuum of unfolding reversibility, the paper demonstrates that SSB is not a unitary phenomenon but a family of structurally distinct expressions of unfolding remainder under varying fixation conditions. The paper further distinguishes 8DD-level mating behavior from 9DD-level display behavior, identifies survival pressure as one important regulatory variable among several that modulate the behavioral expression rate of remainder, and advances four non-trivial predictions — each presented with supporting data and explicit falsification conditions. Asking "why does SSB exist" is like asking "why does sculpting produce debris" — the answer lies not in the uses of debris but in the structure of the sculpting act itself.

Keywords: Self-as-an-End, sex determination, same-sex sexual behavior, ESSP, unfolding remainder, 5DD / 7DD / 8DD, chisel-construct cycle, cross-phylum, non-adaptive model, sexual differentiation