Originally Posted by M Levac

I think there's an assumption that needs corrected. Protein is not the "more plentiful energy source". Fat is.

Protein is barely used for energy. Instead, fat is the primary source of fuel. Between plants and animal flesh, it's obvious which provides the most fat and the most readily available fat. With populations that have limited access to fatty animal flesh they supplement their diet with some form of fatty plant like coconut for instance.

As Stefansson observed, lean animal flesh is not suitable on its own. We must eat the fat as well or we quickly suffer. We could argue that the results of various studies showing a problem with meat consumption found a problem because those people did not eat enough fat. I could name a few examples like Kimkins, Ancel Keys or Stefansson to support this idea of toxic protein in the absence of fat. In the case of Kimkins and Ancel Keys, the subjects suffered emaciation. In the case of Stefansson, the subjects suffered from something called rabbit starvation.

On the genetic aspect, we could argue that since humans lost the ability to produce vitamin C our body must see this molecule as an intruder and the body must defend itself against it. However, a hypothesis is based on the facts and the facts show that vitamin C is beneficial to some degree. If other animals have the ability to produce this molecule, it can't be that bad for those who eat them. It can't be bad for those who adapted to eat those animals.

We could also make the case of cholesterol. All our cells have the ability to manufacture cholesterol yet cholesterol is blamed for heart disease. It's absurd to contend that our cells work to destroy the organism that they compose. In a similar manner, it's absurd to contend that NeuG5c is now bad for those who have lost the ability to produce it merely because they have lost the ability to produce it. For this molecule to be deemed bad, we would have to show its effect by excluding all other potential sources of harm. Specifically, we would have to put people on an exclusive all red meat diet for a period of time and see if they develop cancer. Because that is the contention: That this molecule causes cancer in humans.

Correction. The contention is that the molecule causes cancer. This molecule is found in red. Therefore red meat cause cancer.

As history has shown, red meat in any quantity does not cause cancer nor does it cause any ill whatsoever unless the meat in question is still alive when we try to eat it and tramples us to death instead.