A new hypothesis aims to explain how the complex vertebrate body, with its skeleton, muscles, nervous and cardiovascular systems, arises from a single cell during development and how these systems evolved over time. They give it a proper name, embryo geometry, but scientists are going to hold off on calling it a theory until it shows some chance of validation. Until then, it is like String Theory, more philosophy than science.
The paper, along with illustrations - or "blueprints" - depicting how it applies to different vertebrate organ systems, is in Progress in Biophysics&Molecular Biology.