Description: This paper argues that the solar system can produce at most one independently emergent planetary civilization (13DD), via five a priori constraints culminating in the Lonely Star Theorem. The core engine is the colonization timescale asymmetry: post-threshold expansion speed exceeds independent emergence speed by six orders of magnitude. The argument extends fractally to species competition on a single planet. Four falsifiable predictions are given, and a preliminary estimate of galactic 13DD density is offered based on a conjectured cross-scale invariance of the SAE residual rate. Language: English License: CC BY 4.0 Series: SAE Anthropology Series, Prequel Keywords: Self-as-an-End, SAE, habitable zone, 13DD, Lonely Star Theorem, single-lineage emergence, Fermi paradox, planetary civilization, fractal constraint, colonization asymmetry, Kardashev scale, residual rate Related identifiers: SAE Foundation Papers (DOI: 10.5281/zenodo.18528813, 10.5281/zenodo.18666645, 10.5281/zenodo.18727327); SAE Physics Four Forces series (DOI: 10.5281/zenodo.19341042 ff.); SAE Cosmology series (DOI: 10.5281/zenodo.19245267 ff.); SAE Methodology VI (DOI: 10.5281/zenodo.19464506)