Sexualpedia is an open-ended series of articles that will explain the source of many common erotic interests using neuroscience, biology, and online behavioral data.

What lady parts do men find most beguiling? What pieces of male anatomy intrigue women the most? To answer these questions, we turned to our data.

To gain insight into male desires, we counted the number of times that men included different pieces of female anatomy in their sexual searches on Dogpile. (We also counted the number of times that pieces of male anatomy were included in searches for gay sexual content on Dogpile.) Then we gave the resulting frequencies to the graphic artists at Boy Meets Hero ^[1] and asked them to draw us a pair of “sexual homunculi.”

If you’ve ever taken a psychology course, you probably recall the “sensory homunculus” in the chapter about perception. This big-lipped fellow shows the different anatomical divisions of the primary somatosensory cortex, with pieces of anatomy sized according to how much cortical real estate they each take up in our brain. It shows that we have a lot of sensation in our hands and tongue.

Similarly, the sexual homunculus has anatomy that is sized according to how often men search for each body part. The female sexual homunculus features the lady anatomy that men search for. You could perhaps say that this is how the typical male sexual brain perceives women.The male sexual homunculus features male anatomy sized according to how frequently gay men search for each part. You might say that this is how the typical gay male sexual brain perceives men. Keep in mind that the proportionality is only approximate, since it was rendered through an artist’s interpretation of our data and he informed us that “it’s difficult to supersize someone’s butt while keeping their adjacent anatomy normal looking.”

To discern women’s interest in male anatomy, we turned to the romance novel. We analyzed the text of more than ten thousand romance novels published from 1983 to 2008 (including erotic novels) to determine the most common descriptions of the hero’s physical appearance. Here are the seven most frequently mentioned pieces of masculine anatomy:

1. cheekbones
2. jaw
3. brows
4. shoulders
5. forehead
6. waist
7. hips

If we wished to describe the ideal-looking hero, we could use the most common two-word physical descriptions: the perfect hero boasts blue eyes, a straight nose, high forehead, and square jaw together making a handsome face. His head is framed by dark hair which accents the white teeth in his sensual mouth curved into a crooked smile. He stands tall with broad shoulders, a broad chest, narrow waist, flat stomach, strong arms, big hands, big feet, and long legs—though the heroine’s eye might ultimately be drawn to his powerful thighs. We are still awaiting a romance hero homunculus, though we aren’t quite sure what a crooked smile looks like.

There’s one notable difference between the female sexual brain and the gay male sexual brain: in the hundred most common physical descriptors used to describe the romance hero, there is no synonym for penis.

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Dr. Ogi Ogas received his PhD in computational neuroscience from Boston University and was a Department of Homeland Security Fellow. His writing has been published in the Boston Globe, Wall Street Journal, Glamour, Wired, Baltimore Magazine, and Seed.  He used his knowledge of cognition to reach the million dollar question on Who Wants to Be a Millionaire and battle Ken Jennings in the finals of Grand Slam.