Prions very rarely affect other species, vCJD was unusual in that it was a cow cannibalism illness (mad cow disease) that also caused fatal mental illnesses in humans.

Sheep prions mess up sheep but not us, you’re incredibly unlikely to get a prion disease from a random wild animal, and you’re very safe if you only take healthy animals

The only populations that still live off the land that suffer prion disease are those that practice cannibalism. All of them eat brains. Humans probably evolved taking brains from lion kills; bashing the skulls open with rocks the same way chimps bash open nuts

Sheep prion disease doesn’t affect humans

Beef prion disease came from feeding beef beef waste including beef brain. It isn’t much of a risk

Human prion disease happens in populations where people eat people’s brains

Brains run on ketones when ketones are present even when glucose is also present. Brains run on ethanol in preference to glucose.

People find their brains work better on ketogenic diets

Lard is rendered pig fat. It would be strange if that cake and pastry ingredient was what brains are made of.

Brains are an excellent emergency baby food, they’re good food regardless with plenty of high energy fat and loads of nutrients

It’s a pretty good fat health wise, lamb brains have been a very popular weaning food. I remember eating brain as a small child