Buzz
We are constantly surrounded by symbols that we intuitively recognize but seldom question their origins. Often, the history behind these common symbols is far more intricate than we imagine.
10. Heart Symbol
The heart symbol's shape dates back to Cro-Magnon pictograms from the last ice age, but its modern meaning likely emerged during the Middle Ages. Some believe it was inspired by the seedpod of the silphium plant, a North African species used for birth control until its extinction. The city-state of Cyrene even minted coins featuring the seedpod, which closely resembled the heart shape, potentially linking the image to themes of love and intimacy.
Others argue for a more spiritual origin, tracing the modern heart symbol to the medieval Sacred Heart, which symbolized the sacrifice of Jesus Christ and was often depicted with wounds. The Catholic Church claims the symbol was revealed to Saint Margaret Mary Alacoque in the 17th century, appearing surrounded by thorns. However, historians note that the symbol was in use long before the 1600s.
Others suggest the heart symbol was inspired by early misconceptions about the human heart, believed to have three chambers, a rounded top, and a pointed bottom. It was thought to be the seat of human emotions. Medieval artists may have popularized this depiction in their works, which later became associated with Valentine’s Day in 17th-century England.
9. Dollar Sign
The symbol widely recognized as the dollar sign originally represented the peso. The Spanish peso de ocho, backed by abundant ore mining in Central and South America, became a global currency. It surpassed the older Bohemian thaler in popularity, though the thaler influenced terms for silver coins in Germanic languages, such as the Slovenian “taler,” Dutch daalder, and the English word “dollar.”
The Spanish peso, however, became the dominant currency in Europe, the Americas, and the Far East. Merchants abbreviated “pesos” as “Ps,” eventually overlapping the letters. By the 1770s, this evolved into the “$” symbol, which the United States adopted to represent its currency.
Several other theories have been proposed about the dollar sign's origin. Ayn Rand suggested it was a combination of the letters “U” and “S,” symbolizing the nation, a free economy, and a free mind. Others argue it was derived from the monogram “PTSI” used by the Potosi silver mines, while some link it to the Portuguese cifrao, the British shilling, or Spanish terms for “slave” and “nail.”
8. Arrow Symbol
Before the arrow symbol became a directional marker, ancient Greeks used footprints, and medieval Europeans used pointing fingers. In Ephesus, a footprint and a woman’s face carved into the pavement directed visitors to a brothel. Medieval signage and early printed texts featured extended fingers, known as printer’s fists or manicules, which some trace back to the 12th century, gaining popularity in Italy during the 14th and 15th centuries.
The arrow symbol wasn’t widely used for direction until the 18th century, initially appearing in engineering diagrams and maps to indicate river flow. Early arrows included visible arrowheads and shafts, but by the 19th century, the fletching disappeared, and the arrowhead became more abstract, often depicted as triangles or intersecting lines. By the 20th century, the arrow evolved into a fully abstract symbol, used in logic and mathematical sets.
7. Mathematical Signs
The symbols for addition and subtraction first appeared in the 15th century. The “+” sign likely originated as an abbreviation of the Latin word et, meaning “and.” Ancient Greeks used the letter “psi” for addition, while Hindus used yu, and Egyptians depicted addition and subtraction with symbols of walking legs. Early 15th-century Europeans used “p” and “m” for “plus” and “minus,” but the first recorded use of “+” to mean et was by astronomer Nicole d’Oresme in the 14th century.
The “–” sign may have come from merchants marking unloaded cargo or as a shorthand for the letter “m,” which often had a line over it to indicate subtraction. Interestingly, the modern division sign was initially used for subtraction by northern European mathematicians and may have originated from notations marking questionable or incorrect passages in manuscripts.
These symbols became widely used in mathematics by the late 16th century. Mathematicians Johann Widman and Vander Hoecke used them in the 15th century, and Robert Recorde introduced them to English notation in 1557, stating, “There be other 2 signs in often use of which the first is made thus + and betokeneth more: the other is thus made — and betokeneth lesse.”
6. Asterisk And Dagger
Once rare and paired with the dagger, the asterisk has gained widespread popularity due to its use on the Internet. Traditionally, both symbols were used in footnotes, marked birth and death dates in European typography, and indicated pauses in Gregorian chants. Some trace the asterisk’s origins to ancient Sumeria, where the cuneiform symbol dingir or an represented “heaven” or “divinity,” though this connection is debated.
A more credible history links the asterisk and dagger to the Library of Alexandria, part of the Mouseion learning center. Athenian official Peisistratus paid by the line for Homeric verse, much of which had been lost. Many submissions were fraudulent, prompting Zenodotus of Ephesus, a Mouseion grammarian, to review the works and mark fake verses with a single line in the margin.
Zenodotus’s line, called the “obelus” (Greek for “roasting spit”), evolved into the dagger symbol. The asterisk was later introduced by Aristarchus of Samothrace, who edited Zenodotus’s work. Aristarchus created symbols like the angled diple for noteworthy passages and the spotted diple for disagreements. He paired the obelus with a star-like glyph called asterikos, or “little star,” to mark duplicated or misplaced passages.
Early Christians, particularly Origen, adopted these symbols to reconcile the Hebrew Old Testament with its Greek translation. Over time, the symbols’ shapes and meanings evolved, passing through Christian scholarship with varying interpretations.
5. Exit Signs
Two major standards for exit signs exist globally. The United States uses bold, red “EXIT” signs, chosen for high visibility and association with danger. In contrast, much of the world uses a green pictogram of a running man exiting a door, which is universally understandable and associated with safety.
The US exit sign originated after the 1911 Triangle Shirtwaist Fire, which killed 146 workers in Manhattan. This tragedy led the National Fire Protection Association (NFPA) to emphasize “life safety” and develop emergency exit signage standards in the 1930s and 1940s. Robert Solomon of the NFPA noted that an English word was chosen over a symbol because the U.S. was “more parochial” at the time.
In later decades, graphical symbols gained popularity. A Japanese fire safety association held a competition for a new exit sign, receiving 3,300 entries. Designer Yukio Ota won with his running man image, which was refined to encourage calm movement during emergencies, even adjusting the leg angle to avoid a sprinting appearance.
Meanwhile, the International Organization for Standardization (ISO) was creating global standards to facilitate international trade. The Japanese government submitted Ota’s design for consideration, which outperformed a similar Soviet proposal that included a door in the pictogram.
Although the running man symbol has been widely adopted globally, its acceptance in the U.S. has been slow. This is largely due to cultural familiarity and inertia, as well as the lack of a pressing need for change. NFPA investigations have never documented cases where people failed to recognize the “EXIT” sign, with issues only arising when signs were absent.
4. Radiation Symbol
The universally recognized radiation symbol was created in 1946 by a team at the University of California, Berkeley’s radiation laboratory, led by Nels Garden. The team considered various designs, ultimately choosing one that symbolized activity radiating from an atom. However, the exact reasoning behind the symbol’s selection remains unclear.
The symbol’s design was theorized to represent an atom, with the central circle as the radiation source and the three blades symbolizing alpha, beta, and gamma radiation. It may have been inspired by a propeller warning symbol at a nearby naval dry dock or adapted from an earlier radiation symbol featuring a red dot with radiating lightning bolts. Another possibility is that it was influenced by the Japanese battle flag, which was familiar on the West Coast.
The original radiation signs featured a magenta symbol on a blue background. Garden chose magenta for its distinctiveness and cost-effectiveness, believing it would deter misuse. The blue background was selected because it was rarely used in radiation-related environments.
While some workers felt blue was unsuitable for warning signs, Garden argued that yellow was too common due to its high visibility. In 1948, Oak Ridge National Lab experiments led to the standardization of magenta on yellow. Design variations persisted until the modern version was regulated, with black replacing magenta in some regions outside the U.S.
3. Question Mark
The question mark, once called the interrogation point, has several proposed origins. The most popular theory is that it evolved from the Latin word quaestio, abbreviated as “qo.” Others suggest it may have come from the medieval musical notation punctus interruptus or even the shape of a cat’s tail in ancient Egypt.
Another theory credits Alcuin of York, an English scholar at Charlemagne’s court, with creating the first question mark. His design, resembling a point with a tilde, gained widespread acceptance by the ninth century.
The most recent theory, proposed in 2011, is based on fifth-century Syriac Bible manuscripts known for their use of ambiguous dots. Dr. Chip Coakley of Cambridge University suggests that the zagwa elaya, or “vertical double dot,” marked questions that weren’t immediately obvious, such as “You’re leaving?” While later Greek and Latin question marks were likely independent inventions, if Coakley is correct, the zagwa elaya represents the earliest known question mark in history.
2. Male And Female Symbols
The common explanation for the male and female symbols is their connection to Greek mythology, specifically the Shield of Mars and the Mirror of Venus. However, evidence linking these objects to the symbols is scarce, and their true origins are more intricate.
In ancient astrology and alchemy, celestial bodies were linked to specific metals: the Sun (gold), Moon (silver), Mars (iron), Mercury (quicksilver), Venus (copper), Jupiter (tin), and Saturn (lead). This system influenced 18th-century botanist Carl Linnaeus, who predated modern chemical notation. Before 1814, chemists often used symbols from medieval alchemy.
Linnaeus adopted the chemical notation system for his botanical shorthand, first using it in a 1756 dissertation on hybrid plants and later in Species Plantarum. He assigned the symbols for Saturn, Jupiter, Mars, and the Sun to represent woody, herbaceous perennial, biennial, and annual plants, respectively. The symbols for Mars, Venus, and Mercury were used to denote male, female, and hermaphroditic traits.
Other botanists and zoologists soon adopted these symbols for their simplicity and memorability. Attempts to link them to pictographs, runes, or Babylonian astrology have failed, with most believing they are simplified forms of early Greek script. The female symbol is derived from the goddess Phosphorus (linked to Venus) and the male symbol from the planet Thouros (linked to Mars).
1. Stop Signs
In the early days of automobiles in the U.S., road signage was minimal, leading to chaotic competition among cars, horses, and bicycles. The first stop sign appeared in Detroit, Michigan, in 1915, the same year the first electric traffic signal was introduced in Cleveland. It was a simple 0.6-meter (2 ft) square metal sheet with black lettering on a white background.
In 1923, the Mississippi Valley Association of State Highway Departments established guidelines for signage design based on danger levels. The idea was that the number of sides on a sign indicated the level of hazard. Circles, with infinite sides, marked railway crossings, while octagons represented the second-highest danger. Diamonds were used for warnings, and rectangles for informational signs. According to Texas A&M University Professor Gene Hawkins, “This was created by engineers, who can be overly analytical.”
Early octagonal stop signs had white backgrounds, later changed to yellow. The 1935 Manual on Uniform Traffic Control Devices for Streets and Highways defined the stop sign as a 0.6-meter (2 ft) octagon with a yellow background and red or black letters. A 1954 revision introduced a color code system, adopting red for stop signs once durable reflective red materials became available in the late 1940s. Subsequent updates in 1978, 1988, and 2000 maintained the iconic design, now recognized globally.
