Re: Only partial picture
"One very significant argument is that our human bodies are simply not evolved into consuming the amount of meat products, included in the western mans diet nowdays. For thousands of years (actually until 100 or 200 years ago) the level of meat consumption was much less that the present one in the western world thus a reduction in meet consumption will also have a personal positive health effect."
I'm reminded of the picture of the 50 year old vegan who looks like a troll and the 50 year old chef who loves butter, eggs, meats, & cheeses and looks like quite the hot dish on her own. What is a "personal postiive health effect" for one, might not be for another. In truth if you really want to improve the health of the typical modern human dump the "fortified flour products," corn syrup derivatives, etc. that completely screw up a modern human's insulin levels.
With regard to protein consumption specifically, I'll observe that the average height, size, etc. of the modern human is significantly larger than even just a few hundred years ago - it may be that protein consumption of a few hundred years ago wasn't as adequate to a positive health effect as one might assume on face value.