The Science Behind What Makes Someone Sexy

Aditi Shankardass
Symmetrical faces are more beautiful, like this one, of sexy neuroscientist Aditi Shankardass.

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This is part of our series on the Sexiest Scientists Alive.

People often think that sexiness is in the eyes of the beholder and is inextricably linked to cultural norms, but that isn’t completely true.

When you dig into the human brain there are a few things that almost everyone uses to determine a person’s attractiveness — at least, on the physical scale.

In general, we are attracted to the people who would make the best genetic match for us — those who are fertile, have good genes, and whose immune system complements ours. By mating with someone who is healthy and has good genes, we can pass those genes down to the kids we have with them.

Nina Tandon
The beautiful clear skin of sexy engineer Nina Tandon is attractive.

[credit provider=”Graeme Mitchell”]

Our bodies and brains have been tuned to spot these genetic traits through physical features in the face and body. Upon first attraction, these are what we all look for:

  • Clear, smooth skin shows that we are healthy, especially in the faces of women.
  • Symmetrical faces (which means the two sides of the face line up if you fold it down the middle) are beautiful, they also look younger and healthier. How symmetrical your face is is an indicator of your genetics, and even how good your environment was growing up. These both make for better mates. This is even evident in infants, who look longer at more symmetrical faces.
  • For females, when it comes to faces, men prefer higher forehead, fuller lips, an shorter jaw and a narrower chin.
  • The ideal face of an attractive woman has high cheek bones, big eyes and a thin jaw.
  • Clear eyes are important, since red and watery eyes are thought to be “sad and unattractive.”

Symmetry is also important when it comes to the body.

  • Men also prefer a waist-to-hips ratio of 7:10. Weight doesn’t matter. Hip width and breast size are important factors in fertility, child birth, and rearing, so there’s definitely an evolutionary connection there.
  • The ideal waist-to-hips ratio for men is 9:10.
  • The ideal male has a big jaw, a broad chin and an imposing brow. The angle between their eyes and mouth, cheekbone prominence, and facial length all play a role as well.
  • A youthful look is attractive because fertility drops as we age. Evolutionarily speaking you wouldn’t want to mate with someone who can’t bear you children.
  • A recent paper suggested that the best body fat percentage for a man is 12 per cent. Body fat percentage seems to be an indicator of how well your immune system works.
  • A BMI (Body Mass Index) of 20.85 has been determined as the most attractive weight for a woman.
  • Men are generally regarded as attractive if they are broader at the shoulder and narrower at the hips (the general “V” shape) women find a slim waist and a muscular chest attractive on men as well.

One other factor? Your smell:

  • While humans don’t have pheromones (chemical attractants secreted by animals to find mates) smell does play a role in how attracted we are to someone. Studies have found we can find our immune system match (whose genes complement ours, leading to healthier babies) by their smell.
Deva Ramanan
Sexy computer scientist Deva Ramanan is handsome AND smart.

[credit provider=”Photo courtesy of Deva Ramanan”]

Just as a parting comment, these are the physical features that evolutionarily determine sexual attractiveness. Everyone is attracted to different things and when it comes to actually having a relationship and emotional connection with someone, these factors play a much smaller role.We all know an attractive face and body can quickly become unappealing if paired with an ugly personality. A recent study actually suggested that beautiful women are more likely to have less attractive values, favouring conformity and self-promotion over independence and tolerance.

Knowing scientists, though, we doubt that our sexy female researchers fall under that category.

“I believe that each of us perceives each person they meet as beautiful or not because of a combination of physical and mental factors,” Robert Tornabe, a plastic surgeon in New York City, wrote in a blog post. “It is my contention that certain negative characteristics of one’s personality can actually make that person less attractive and less physically appealing.”

One thing our sexy scientists don’t have to worry about? Being perceived as dumb. These men and ladies are whip smart and accomplished, a trait that many people find sexually desirable.