Earlier quoted context omitted.
How the brain grows and develops in humans is not very well understood. We mostly use animal models to understand the nervous system, not humans. As an example of why this is problematic: mouse embryos pretty much turn inside out at day 3, and are the only known mammal to do this. All others, including humans, don't. Why and how are unknown, as are the effects on long term development. Basically, mice are better subj…
Embryology is a fascinating field. How does a single cell develop into a functional animal? This process developed under evolutionary pressure.
Take all the hard parts of bio normally, and now add in a ton of mitosis, long range movement of cells, hard to detect chemical gradients, cell-to-cell junctions, and pure random chance. All just going bananas fast for 'normal' bio processes.
It is a crazy tough field to get work done in. No wonder no one uses mammals to do anything.