Here's Why Zombie Drew Barrymore Is So Horny in 'Santa Clarita Diet'

Caution: Light spoilers for Santa Clarita Diet ahead.

As Drew Barrymore’s undead suburban housewife Sheila Hammond gruesomely illustrates in Netflix’s new Santa Clarita Diet, zombies are just like us: They get hungry, they’re impulsive, and they get really, really horny. As Eric, the nerd next door explains, it’s because “the undead are completely driven by their id.” Eric’s reliance on Freudian theories is outdated, but their modern correlates offer up a decent explanation for why Sheila’s so eager to get laid.

In Sigmund Freud’s three-part theory describing the structure of the human psyche, the id is the part of the mind responsible for our most basic animal drives: eating, killing, and getting it on. It’s outranked by the ego and superego, which work together to keep the id under control. Zombies, as they’re generally portrayed in pop culture, are essentially flesh-eating animals (granted, Sheila seems to have some ego function in the pilot), so Eric’s finger-pointing at the id isn’t wrong, exactly. It’s just that modern neuroscientists, dismissing Freud as unscientific, prefer to think of the id as the unconscious — the mysterious part of the mind that runs on autopilot.

It’s thought that our most basic sexual drives live in the non-conscious mind, but scientists still aren’t entirely sure how they arise. When people get aroused, their brains show activity in the temporal lobe, the hippocampus (the memory center), and the amygdala (the seat of emotion). Sometimes, damage to these parts of the brain causes hypersexuality: People with Klüver-Bucy syndrome, which arises when the both sides of the medial temporal lobe get injured, get super horny. Lesions in other parts of the brain, like the medial basal frontal lobe or the diencephalon, can cause hypersexuality too. The same goes for certain mental illnesses, like bipolar disorder or schizoaffective order. The common thread running through all of these instances of hypersexuality is that in all of these cases, the urges seem to be uncontrollable — definitely not the realm of the conscious mind. After all, animals have lots of sex, and they’re not conscious — right?

The unconscious mind, like it or not, controls more of our behavior than we’d like to admit. In 2015, a study in the journal Behavior and Brain Sciences, noting how slowly the conscious mind actually corrects our behavior, suggested that we are pretty much unconscious most of the time. When Sheila wants to get it on in Santa Clarita Diet, she wants it immediately — her urgent insistence that her husband Joel perform sexual favors for her suggests that she, too, is acting on a basic urge.

So, Eric wasn’t all wrong: As cognitive psychologist Axel Cleeremans, Ph.D., has pointed out has pointed out, Freud’s Id-Ego-Superego theory of the psyche matches up pretty closely to the Unconscious-Conscious-Metacognition model of the mind that is currently accepted by neuroscientists, anyway. Whether either of those apply to zombies remains to be seen, but their similarities do suggest that there’s a lot in common between the dead and undead after all.