That's basically the crux of the entire book. He's a prof at Harvard. It's not a self-help type of fitness book. It's academic almost to a fault (read: great info but not too much fun to read).

If you're looking for similar but more accessible, try "The Comfort Crisis" by Michael Easter. Same general idea (i.e., how today's world is not fitting for the type of world we evolved in) but less into the weeds of the details.