I don't think I've read it, but I've read enough books on food anthropology and on hunter/gatherer vs nomadic herder vs farmer, so I have a pretty good idea. I'll have to look it up. It's the type of thing I'd like.
Basically farming and reliance on grains destroyed human health. Life expectancy at maturity dropped like a rock. All sorts of diseases showed up. Tooth decay which wasn't really much of a thing before then took hold. Archeologists can tell the nomadic herders from the farmers that would occupy the same relative areas at the same time frame by looking at the teeth and bone abnormalities. Farmers had more babies as well and the infant mortality was higher from diet and body stress.
Side note, life expectancy at birth is very different from life expectancy at maturity. The first is the life expectancy they are always touting but infant mortality skews that. If you make it to maturity you're likely to live your hereditary lifespan. So cavemen did not die in their 20s or 30s. Evidence has suggested 50s or 60s and most likely the dangers of age in the environment being cause of death.
I understand that calories isn't accurate. We're not a flame burning things up. So unless you're a bunsen burner it cannot work right. If I looked up the formula I can't remember, I could get a rough idea how many calories are in my firewood by burning a precise amount over a set time. Not everything is digestible. And unlike a flame, we don't actually digest fats that well unless we teach our body to use them. Carbs are the easiest thing and what is stored as our body fat.
Genetics has a lot to do with how much you need to eat. In high school I ran track (distance) and was around 1200 calorie intake. Mom thinks it was less. I didn't eat breakfast, or lunch half the time, dinner was small portions. I was still overweight enough that the Navy almost didn't take me. I was 2 pounds under the cutoff. Weighed 130 and was supposed to be 110. Now granted I had muscle mass from running and doing work at home, but I was still wearing size 8 jeans and the skinny girls were wearing size 4. Looking at the women in my family, they never eat more than a few bites at any meal if they want to stay thin.
Some of it was a surprise for me! Agriculture gave us slavery, poverty, famine, plagues, overpopulation (often followed by infanticide and cannibalism 
), took up to 50 years off human lifespan in some areas, deformities, dental disease.. yikes. But damn, the white bread is tasty! 
I'm only half-way through the book so far!
