It suggests that humans must be carnivores, because our digestive organs are different to Herbivores. I don't know about the author, but last time I checked I was an omnivore.
Reminds me of the caffeine addict who broke his jaw and had it wired shut. The next morning after surgery, he was going through agony because he couldn't have his coffee.
The only way the nurse said it could be done was via a cofffee enema. He agreed, but said he liked his coffee very hot. The nurse warned him, but he insisted.
When it started, the guy started to scream, apparently in pain. The nurse said "I told you it would be too hot."
The man shouted, "No, it isn't hot, it needs more sugar!"