Software Testing Methodologies and the brain
Large software projects are almost entirely driven by test design, because at every iteration of the project, there are many unknowns, but one of the few things that a developer can stand behind is that the software passes a particular number of tests at each release.
I would be surprised if this was not a general truth in “development", and would be shocked if it did not apply to the development of the brain in the human placenta.
It would be an interesting question, how can we isolate the tests that the growing brain must pass to continue to move onto the next phase.