The concept of memes is that of self-replicating entities of human culture, the same way genes replicate through a biological organism. As materialist reductionism says "Cultures are survival machines blindly programmed to preserve the selfish entities known as memes." Memes are thought of as thought-chains that propagate and compete in the cultural environment. Parasitizing the brain, the way a virus parasitizes the genetic mechanism of the host cell, they are described not just metaphorically but technically as living structures. We are talking about living entities living off humans, eating brain when they do not battle themselves in memetic cannibalism, preying on each other like flip-flop cellular automatons.
Out of this some questions arise. Memes are eating brains, but then who harvests memes? Where in the food chain are memes? Maybe they are milked and used to produce cheese. And if it is not the milk, meat or wool, but some body fluid of memetic cultures? Could it be a sexual secretion which is used as an aphrodisiac, like musk or ambergris - when it costs the life of a whale to gain its expensive perfume? Is it not a classic theme of paranoids, psychotics and UFO abductees to report surgical manipulation of body parts related to sexual reproduction?