@OuchThatHurts Sorry, for some reason it wouldn't let me quote you.
I'm a bit rusty on my food chemistry, but eggs in their raw form will have weak hydrogen bonds. When heated, the protein will denature, or uncoil, and they will not be able to revert/refold back to their original structure. However, after denatured, and with continued heat, the protein can form bonds with other molecules and refold into stronger bonds. Through this process (I can't give a reason why) it can increase protein digestibility. Raw eggs, when cooked will lose some nutrients in it's favor, but I think these losses can be somewhat mitigated to a large degree by using low-med heat and not overcooking. So there is kind of a happy-medium state where you are trying not to over-cook the egg and lose certain nutrients (O-3/DHA, Vit D, etc), but cook enough to strengthen the new protein bonds and improve protein digestibility. One thing maybe some people get confused on when it comes to denaturing proteins is that they think it can/will change the primary structure of the protein, which is not the case. Similar to the illustration that USMC posted above, if you have a shoestring that is tied into a knot, but untie it (by hand, but in the case of proteins in eggs it would be heat or pH, or by agitation/beating), you will still have a shoestring as the primary structure, but it has been untangled, or in the case of proteins, it's been altered/denatured. Some proteins can refold back to their original state, but in the case of eggs, they can't and it's permanent...at least it was the last I checked.
I believe there was 1-2 studies that showed better 'protein' absorption from cooked eggs, I know i've posted 1 in the past, but i'd have to look for it. I had this same exact discussion with a few of my food chemistry teachers, ugh...many years ago, and they had mentioned the same thing when I asked them, in that the way the proteins get refolded (or more precise the stronger bonds formed) when heated improves the protein for better absorption compared to raw. They didn't know why that was the case either, lol.
Pasteurization of egg whites has been cooked just enough to improve digestibility, safety....and avidin deactivation so that it doesn't bind to biotin. This all may be moot if one does consume extra biotin. I know you already know all this....
Yea man, i'm not sure on when humans started cooking eggs. I'd have to look that up, it's probably easily accessible though with a simple search.
I would also say, with like almost all we do, i'd stick to whatever is working for each person....no need to complicate things.