Like height the link is probably though health and generally freedom from birth defects. It's not a 1:1 correlation, but it is a positive one.
Consistent with such views, meta-analyses
(Jackson, Hunter & Hodge, 1995; Langlois et al., 2000) show that
there is a small but significantly positive correlation between
intelligence and physical attractiveness https://personal.lse.ac.uk/kanazawa/pdfs/I2011.pdf
That said, selected populations may show a negative correlation such as when more attractive people are more easily given a job etc.
