When Did the Flat Earth Become a Globe?

A wind farm with the lower parts of the more distant towers
increasingly hidden by the horizon, demonstrating the curvature of the Earth

The persistence of the "Flat Earth" theory in the 21st century represents a sociological anomaly. Despite a rigorous empirical record dating back to antiquity, modern proponents have coalesced into a decentralized digital subculture.

Contemporary Flat Earth belief is not characterized by a formal institutional hierarchy but by a decentralized digital network. While the historical Flat Earth Society remains a vestigial entity, primary discourse occurs via social media platforms, video-sharing sites, and specialized forums.

This movement is underpinned by a profound institutional distrust. Proponents categorize data from governmental agencies (such as NASA) and mainstream scientific communication as part of a multi-generational systemic deception. This "anti-establishment" epistemology prioritizes subjective observation over established scientific consensus.

A common historical fallacy—often termed the "Flat Earth Myth"—suggests that medieval society lacked basic geographical and astronomical literacy. In reality, the spherical nature of the Earth was a settled matter among the educated elite throughout the Middle Ages (approx. 5th to 15th century).

While the Middle Ages are often oversimplified as a period of intellectual stagnation, the reality was more nuanced:

• Literacy Rates: Western European literacy was statistically low, often estimated below 20%.

• Scholarly Continuity: Despite low general literacy, the "spherical Earth" model was preserved through the transmission of Classical texts.

• Common Knowledge: It is hypothesized that even the non-literate population understood the Earth’s curvature through practical observation and the trickle-down of scholarly consensus into general folklore.

Flat Earth map drawn by Orlando Ferguson in 1893. The map contains several references
 to biblical passages as well as various supposed refutations of the "Globe Theory".

The empirical evidence for a spherical Earth was established long before the medieval era, primarily through Greek mathematical and observational astronomy.

Key Empirical Milestones

Figure	Period	Contribution
Aristotle	4th Century BCE	Identified that the Earth casts a circular shadow on the Moon during lunar eclipses and noted that ships disappear "hull-first" over the horizon.
Eratosthenes	c. 240 BCE	Utilized the varying angles of solar shadows in different latitudes (Syene and Alexandria) to calculate the Earth's circumference.

The calculated circumference by Eratosthenes was remarkably accurate, utilizing a formula with the arc length between two locations, the Earth's radius, and the difference in the angle of the sun's rays.

The existence of modern Flat Earthers is not a result of a lack of evidence, but rather a rejection of the scientific method and the institutions that uphold it. Despite the robust proofs provided by ancient polymaths and confirmed by centuries of maritime and space exploration, the movement thrives on the democratization of misinformation in the digital age.

Your Oldest Female Ancestor: Mitochondrial Eve

If we could trace everyone's family trees as far into the past as possible, you’d find we’re all related. Yes, extremely distant relatives. But the common female ancestor from whom all humans are descended is Mitochondrial Eve, and scientists believe she lived in Africa some 200,000 years ago. 

Before people start posting comments here about the Bible and the Garden of Eden, let's say that the idea of a common ancestor has led to the misconception that this ancestor, Mitochondrial Eve, was the first female human, which isn’t correct. She was the most recent common ancestor to whom every living person can trace their genealogy. 

This Eve is technically known as Mitochondrial-Most Recent Common Ancestor, or mt-Eve and mt-MRCA for short, and her lesser-known male counterpart is known as Y-chromosomal Adam. He’s also believed to have lived in Africa, around 150,000 to 300,000 years ago.

Every human on the planet carries the Eve gene, including 147 people and fetuses from the original 1987 study. That study wasn’t the first to hypothesize a common ancestor, but the researchers behind it did coin the term Mitochondrial Eve.

Because one entire branch of the human lineage is of African origin and the other contains African lineage as well, the study's authors concluded Africa is the place where this woman lived. Recent research may have narrowed down this Eve's home as an oasis in the Kalahari Desert, making it the “ancestral homeland of all humans alive today,” according to the researchers. The Kalahari Desert is a vast, semi-arid sandy savanna in Southern Africa, covering a large portion of the region across several countries.

More on the technical details: a “mitochondrial Eve” refers to mitochondrial DNA, the unique genetic code that is passed down from female to female. Mitochondrial DNA, which is responsible for energy metabolism, is cordoned off from the rest of our DNA, sitting off on its own in its own container. 

What about the actual biological Eve? It is not a woman. You would have to seek out the ancestor of our mitochondria. It would be a single cell that engulfed an even smaller single cell and eventually developed a symbiotic relationship that continues to this day. That is what made the ancestor of you, dinosaurs, trees, and butterflies. 

The Earliest Modern Humans

 The most current scientific understanding of the earliest modern humans—Homo sapiens—points to a complex, pan-African origin rather than a single birthplace or moment in time.

• ~800,000 years ago: Genetic divergence from Neanderthals and Denisovans begins.

• ~315,000 years ago: Jebel Irhoud, Morocco — earliest known Homo sapiens fossils.

• ~260,000 years ago: Florisbad, South Africa — partial skull with modern traits.

• ~233,000 years ago: Omo Kibish, Ethiopia — anatomically modern human remains.

• ~160,000 years ago: Herto Bouri, Ethiopia — Homo sapiens idaltu, an early form of modern humans.

This timeline reflects the current consensus that modern humans evolved gradually across Africa, with multiple populations contributing to our genetic and anatomical heritage. Let me know if you'd like a map version showing the fossil sites or a chart comparing traits across these specimens.

The oldest known Homo sapiens fossils come from Jebel Irhoud, Morocco, dated to about 315,000 years ago. These remains show a mix of modern facial features and archaic braincase shapes, suggesting a gradual evolution.

Other Early Sites:

Omo Kibish, Ethiopia: Fossils dated to around 233,000 years ago, with features typical of modern humans.

Florisbad, South Africa: A skull dated to ~260,000 years ago, showing a blend of archaic and modern traits.

Herto, Ethiopia: The Herto Bouri skull (~160,000 years ago) is classified as Homo sapiens idaltu, an early form of anatomically modern humans.

Genetic Evidence: DNA studies suggest that the lineage leading to Homo sapiens diverged from Neanderthals and Denisovans between 500,000 and 800,000 years ago, with genetic mixing occurring both within Africa and later in Eurasia.

Pan-African Evolution: Rather than emerging from one region, Homo sapiens likely evolved across multiple African populations that intermittently mixed due to climate-driven migrations. This mosaic evolution helped shape our species’ genetic diversity

Imposing Order on the World

The Frans Hogenberg portrait (1574) shows him pointing at the North magnetic pole.

This is not a leap year with 366 days and a February 29 is a reminder of the ways we (try to) impose order on the world. Some of those ways seem to work pretty well - atomic clocks, GPS, compasses, maps, and globes. One person who tried to impose some order on our world who we can learn about in the One-Page Schoolhouse today, is Gerardus Mercator. If you need a one-word description of him, it would be "mapmaker," but that is rather limiting. You could add cartographer, geographer, calligrapher, engraver, a maker of scientific instruments, and a publisher. He was interested in mathematics, astronomy, cosmography, terrestrial magnetism, history, philosophy, and theology.

Gerardus Mercator (5 March 1512 – 2 December 1594) was from the County of Flanders. He is most renowned for creating his 1569 world map based on a new projection. Mercator was one of the pioneers of cartography and, in his time, was known as a maker of globes and scientific instruments.

Mercator's early maps were in large formats suitable for wall mounting, but in the second half of his life, he produced over 100 new regional maps in a smaller format suitable for binding into his Atlas of 1595. This was the first appearance of the word Atlas in reference to a book of maps. However, Mercator used it as a neologism for a treatise (Cosmologia) on the creation, history, and description of the universe, not simply a collection of maps. He chose the word as a commemoration of the Titan Atlas, "King of Mauretania", whom he considered to be the first great geographer.

This world map was made by Mercator on two sheets in 1538. Only two copies of the map are extant.
This one is from the American Geographical Society Library; another is at the New York Public Library. 

In 1538, he produced his first map of the world, usually referred to as Orbis Imago. But it is his 1569 world map for which he is still remembered. You may have heard of the Mercator Projection, especially if you are a sailor. This cylindrical map projection became the standard map projection for navigation because of its unique property of representing any course of constant bearing as a straight segment.

Such a course is known as a rhumb or, mathematically, a loxodrome. Using it navigators can sail in a constant compass direction to reach its destination, eliminating difficult and error-prone course corrections.

But, as with many manmade ways of imposing order on our world, his constant linear scale in every direction has side effects. The Mercator projection inflates the size of objects away from the equator, starting almost imperceptibly but accelerating with latitude to become infinite at the poles. That means that while landmasses near the equator appear accurate,  landmasses at the poles, such as Greenland and Antarctica, appear far larger than their actual size.

The Mercator world map of 1569 is titled Nova et Aucta Orbis Terrae Descriptio ad Usum Navigantium Emendate Accommodata. That is Renaissance Latin for "New and more complete representation of the terrestrial globe properly adapted for use in navigation."

While the map's geography has been superseded by modern knowledge, its projection proved to be one of the most significant advances in the history of cartography.

Mercator's 1569 world map showing latitudes 66°S to 80°N.