The existence of the first-generation fermion particle leptons and quarks, and their antiparticles, and the forces, pretty much "fall directly out of the structure of E8",
so you could say that E8 sets the stage qualitatively.
The properties of the Standard Model and Gravity forces "require additional theories/mathematics"
such as Meinhard Mayer's Higgs mechanism, MacDowell-Mansouri Gravity, M4 x CP2 Kaluza-Klein,
and
particularly for actual calculation of numerical masses and force strengths,
the mathematics of Complex Bounded Domains and their Shilov Boundaries,
which was developed by Hua Luogeng.
Since the numerical calculations are the critical thing for falsifiability tests,
the work of Hua Luogeng seems to me to be the most important single element,
the "keystone" so to speak.
Tony Smith
PS - I do not live in Valdosta, but I visit there often.
