The Rarest Body Features, According To Science

The human form is an incredible thing. Not only is it capable of amazing feats (we’ll never forget moms straining to lift their kids into cars), but every person’s body is a unique collection of parts, features, and qualities. And we’re not just talking about fitting into the Kibbe system’s 13 body types. Think of all the ways our bodies look and act differently—everything from ear shape and hairline to flexibility and even perception can vary from person to person. Fortunately, being unconventionally attractive pays off, as it makes your unique appearance appealing and memorable.

Of course, some looks and traits remain more common than others. So what kinds of physical characteristics really stand out? To learn more about the unique variety of the human body, Glam spoke exclusively with Dr. Raj Dasgupta, four-time board-certified physician and chief medical advisor for Fortune Recommends Health. Tackling fascinating idiosyncrasies like heterochromia and synesthesia, Dr. Dasgupta showed us some of humanity’s rarest bodily features and traits.

Multicolored eyes are an unusual but compelling feature

They say the eyes are the windows to the soul, and society seems to place a lot of importance on admiring beauty. Certain eye colors are even considered more attractive. But did you know that some people can boast more than one shade of iris? It’s a unique physical peculiarity known as heterochromia.

“Heterochromia is when a person has two different colored eyes,” Dr. Raj Dasgupta tells Glam exclusively. Apparently, this can be due to a number of factors. As the doctor continues, heterochromia can be “caused by genetics, injury, or conditions that affect melanin, the pigment in the iris.” Whatever the cause, multi-colored eyes are a rarity. According to WebMD, only 1% of people worldwide have heterochromia—that’s about 82 million people worldwide.

There are some famous examples of heterochromia among celebrities, such as actresses Jane Seymour, who has one green eye and one brown eye, and Kate Bosworth, who has one blue eye and one hazel eye. But it’s possible for heterochromia to go unnoticed: Sometimes, the trait can be hard to spot if the shades are similar or don’t take up the entire iris. That’s right, heterochromia can even manifest itself with multiple colors in the same eye, creating a striking mosaic effect. One example of this interpretation of heterochromia is Saved by the Bell star Elizabeth Berkley, who has one eye that’s half brown and half green.

Most people have two nipples — but some people have more

Unlike many other mammals, humans have evolved to stop having large nipples—after all, we don’t usually give birth to entire litters of offspring, and often a pair of nipples is enough to survive. But there are still cases where newborns may arrive with an extra bump or two. “Supernumerary nipples are extra nipples along the chest or abdomen, resulting from leftover tissue from fetal development that look like moles,” Dr. Raj Dasgupta.

Because of their mole-like appearance, some people may not even realize they have extra nipples. The location is a good clue: These appendages tend to appear along two hidden ridges called milk lines, which run from under the armpit to the groin. Most often, a person will have just one supernumerary nipple, which appears below their regular nipples, making a total of three. But occasionally, someone can be born with four, five, or even up to eight nipples.

Fortunately, supernumerary nipples are usually harmless and can even be removed. However, there’s no reason to feel self-conscious about these inconspicuous features. Supernumerary nipples are estimated to occur in around 6% of the population, according to DermNet, and even stars like Mark Wahlberg and Lily Allen have spoken openly about their vestigial nipples. So while these extra bumps are unusual, they’re not totally unheard of, and those who have them are in respectable company.

Having concentrated taste buds can turn you into a rare supertaster

Typically, having multi-colored eyes or extra nipples only affects your appearance. But some uncommon features can also affect how you experience the world—this includes having a larger than average number of taste buds, which can classify you as a “supertaster.” As Dr. Raj Dasgupta tells, “Being a supertaster means having a stronger sense of taste, due to more taste buds and certain genes that make flavors, like bitter or sweet, more intense.”

At first, being a supertaster sounds fun. Who wouldn’t want to enjoy a deeper flavor of their favorite foods? However, this ability can easily backfire. Remember, Dr. Dasgupta noted that supertasters are extra receptive to flavors like bitter, which could ruin the experience of eating foods with bitter undertones, like broccoli, beer, coffee, and even chocolate.

Ultimately, it all comes down to taste buds. Adults typically have between 2,000 and 4,000 taste buds, most of which are located across the entire tongue. This equates to about 15 to 35 taste buds in each 6-millimeter section. Meanwhile, supertasters can have anywhere from 35 to 60 taste buds in the same area — about twice as many. According to Healthline, up to 25% of the population has enough extra taste buds to be considered supertasters. So if you know someone who is especially picky about food, it’s possible that their taste receptors are more sensitive. On the other hand, a quarter of the population has fewer taste buds than average, resulting in “nontasters” who are probably happy to eat just about anything.

Folks with synesthesia experience the five senses in surprising ways

Many of our features are related to the five senses: the nose senses smell, the ear senses sound, and the eyes process sight. But sometimes the most unusual bodily traits aren’t so obvious. Dr. Raj Dasgupta draws our attention to an uncommon connection known as synesthesia. As he, “Synesthesia is when one sense triggers another (such as hearing sounds and seeing colors) because of unique brain wiring that connects different senses.”

For those of us who don’t have synesthesia, the effect can be hard to imagine. What does it really mean to experience extrasensory reactions? Often, this triggers unexpected correlations in the brain. For example, someone with synesthesia (also called a “synesthete”) might see colors when they hear sounds, experience a specific taste when they see or hear certain words, or hear an imaginary noise after smelling something.

Much like being a supertaster, synesthesia sounds a bit like a superpower. It’s no surprise that it’s sometimes linked to art. Famous creators from the past and present who suffer from synaesthesia include Billie Eilish, Marilyn Monroe, Kanye West, Nikola Tesla, and even Beyoncé. However, because synaesthesia is uncontrollable, it can sometimes be annoying and distracting, for example by making it difficult to read fluently. In any case, it remains a relatively rare trait: according to the Cleveland Clinic, it’s thought that at least 4% of people may have synaesthesia, although it’s difficult to track all possible variants.

Mirror-touch synesthesia takes empathy to the next level

Among all the interesting and wild synesthesia subtypes, Dr. Raj Dasgupta made a point to mention a particularly unusual variant known as mirror-touch synesthesia. “Mirror-touch synesthesia occurs when someone feels a touch on their own body simply by watching another person being touched,” he tells us exclusively. Typically, this experience occurs as a reflection: If you see the person in front of you being touched on the left shoulder, you might feel it on your own right shoulder, giving the condition its “mirror-touch” name.

Dr. Dasgupta reveals that the basis of mirror-touch synesthesia is due to “additional connections in the brain’s mirror neuron system.” Interestingly, there may also be a connection between mirror-touch synesthesia and empathy. A 2017 study in Cognitive Neuropsychology found that participants with this neurological trait were better able to detect emotions when shown photographs of facial expressions, suggesting a level of emotional sensitivity that is above the norm.

Unlike general synesthesia, which occurs in 4%, the University of Delaware estimates that mirror-touch synesthesia only appears in 2 out of every 100 people — or 2% of the population. Sometimes, this neural quirk can be a pleasant experience for synesthetes, such as when they get passive pleasure from watching someone get a hug or a massage. But mirror-touch synesthesia can also be a double-edged sword. Other times, it’s so intense and overwhelming that people with mirror-touch basically stay housebound in an attempt to avoid stimulation. And as one synesthete on Reddit confessed, “Mirror-touch can make the movie-watching experience very complicated.”