Manali MacRae’s expression is like a child’s retelling of a nightmare.  “When I was younger, I tried to trim my eyebrows with a pair of scissors on Christmas Eve, but ended up cutting one off entirely,” says the 21-year-old Furman University student. “All that was left were tiny patches here and there. It was the worst decision of my life, hands down."

The truth of her statement shouldn't be underestimated: The brow has long been cherished in its countless forms, whether natural or aesthetically enhanced. Ancient Egyptian women viewed their arches as a matter of life or death. Owners shaved their eyebrows when mourning their deceased cats, one of the most cherished animals in Egypt. When not commemorating their pets, they used kohl and mesdemet, substances derived from lead, to darken their arches (mesdemet served a dual purpose—it also worked to disinfect and keep insects away). The 69 BC aesthetic is still seen in modern times: Elizabeth Taylor showcased bold, black eyebrows in the 1963 film Cleopatra, and Kim Kardashian replicated the look on a 2011 Harper’s Bazaar cover.

The Egyptians weren't alone. Women in ancient Greece used powdered antimony to enhance their brows, while others wore false eyebrows made of dyed goat hair and attached them to their forehead with natural tree gum, according to Victoria Sherrow's Encyclopedia of Hair. Later, in Elizabethan England, many women removed or lost their eyebrows completely after repeated use of a harsh facial product called ceruse, which contained white lead. The powder lightened skin, à la Queen Elizabeth I, but caused skin irritation and hair loss through lead poisoning.

Today, American women rely on cosmetic products to achieve the same brow effects as the ancient Egyptians and Greeks. In 1919, American chemist T.L. Williams developed a product inspired by his sister’s habit of mixing Vaseline with coal to darken her arches and lashes. Years later, the invention went on to become the first product released by the cosmetics brand Maybelline.

The concept of the ideal brow has since fluctuated widely. Hollywood film siren Greta Garbo popularized pencil-thin brows in the 1920s, while Madonna preferred them lushly overgrown in the 80s. Mexican painter Frida Kahlo, who died in 1954, used her eyebrows to poke fun at conventional beauty norms. The artist, who was famous for her unibrow, once wrote, “Of my face, I like my eyebrows and eyes.” Dot Tuer, the curator of the 2013 art exhibition “Frida & Diego: Passion, Politics, and Painting,” said in an interview with the Toronto Sun, “Kahlo had a great sense of humor, a great love of life, so the unibrow is supposed to be funny.”

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Zoologist Desmond Morris has proposed that eyebrows primarily exist not for their aesthetic value, but to nonverbally communicate emotion—a raised brow may indicate skepticism while a furrowed brow can show displeasure. Morris never listened to his patients but rather watched, only observing and recording their facial expressions. In his 2007 book, Watching: Encounters with Humans and Other Animals, Morris reveals that humans only move their eyebrows in five distinct ways: We raise, lower, knit, flash, or cock them.

A 2011 study at MIT asked participants to identify 50 famous faces, including Richard Nixon and actress Winona Ryder. A series of photographs showed the faces with both eyes and eyebrows, without eyes, or without eyebrows. According to the results, participants were able to identify the popular figure without eyes 60 percent of the time. However, when the celebrity lacked eyebrows, viewers recognized them only 46 percent of the time—suggesting brows are critical to facial recognition, even more so than eyes.

Sheila Curtis, a cosmetologist whose professional title is “eyebrow artist,” backs these results up. “We talk with our brows, not our eyes. When making eye contact, people look at brows more than eyes,” she says. “It’s how people read us.” Curtis has been responsible for grooming some of Nashville, Tennessee’s most famous brows for nearly 20 years. Amy Grant, dubbed “The Queen of Christian Rock,” and Karen Fairchild, part of the country quartet Little Big Town, are two of her clients.

Eyebrows may also be crucial to how animals read our faces. Joseph Jordania, an evolutionary psychologist at the University of Melbourne, has investigated the brow’s potential to defend humans from predators. When we sleep, the eyebrow and eyelashes form what Jordania calls an “eyespot,” a shape that mimics an open eye. Potential predators, especially larger cats, are tricked into thinking the sleeper is awake and alert, an advantage that could have protected humans in the early days of civilization.

In some places, brows still serve as a line of defense against the dangers of the natural world. The Sundarbans forest (located in Bangladesh and India) is home to a population of Bengal tigers. According to forestry officials and the wildlife trust of Bangladesh, the animals kill between 60 and 80 humans each year. Starting in 1989, when going into the forest to fish, villagers began wearing human masks on the backs of their heads, as the tigers typically attacked from behind. The masks, made of a lightweight rubber, displayed human eyes and brows, creating the protective eyespot Jordania references. This temporarily eased the death toll, although locals reported in 2012 that the animals seemed to have caught onto the trick.

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Hundreds of miles from the Sundarbans, presumably safe from tiger attacks, some women reportedly pay up to $8,000 for eyebrow transplants to get the brows of their dreams. “The most popular celebrity brows my patients ask for are Kim Kardashian, Megan Fox, and Angelina Jolie,” says Dr. Marc Dauer, a Los Angeles surgeon specializing in eyebrow transplants. A 2014 study by the Hair Science Institute in the Netherlands explains how scarring and inflammatory diseases can result in eyebrow loss—so some transplants are reconstructive. However, Dauer says most of his patients want transplants because they have over-tweezed or over-waxed. “Eyebrow hair is different than any other type of hair on the body. If tweezed or waxed, it very well may not grow back,” he says. “My practice has greatly picked up since the bold brow trend emerged, especially over the past two years."

In a process referred to as “follicular unit transplantation,” hair from the center of the back of the head—the part of the scalp where wounds heal most easily—is transplanted to the patient’s brow region. Dauer, one of the first to perform the procedure, says, “I individually place anywhere from 400 to 450 hair follicles, what we call ‘hair grafts,’ onto each eyebrow. The process usually takes all day,” he says. After the procedure and a few days of swelling, the grafts scab over and fall out within a week’s time. Stem cells from the transplanted hair then slowly encourage new growth after five to six months. According to Dauer, the patient will not see the full effects of the procedure until nine months later at the earliest.

Ashley Wilkins, a 26-year-old interior designer from San Francisco, paid Dauer $5,000 to get her brows back. “Since my mom was never into beauty, I naively over-tweezed when I was young,” she says. “For some reason, they never grew back.” After the surgery, Wilkins' face swelled for four days. “It was like something out of a horror movie,” she says. “I went to the airport and people were staring like they had never seen anything like me in their lives.”

But nine months later, Wilkins says her hair grows so fast she needs to trim her brows every few days. “I finally feel normal,” she says. “Now that I have brows, I just feel like I am myself. This is my face now."