Iceland is known to the rest of the world as the land of Vikings and volcanos, an island caught between continents at the extremities of the map. Remote and comparatively inhospitable, it was settled only as long ago as the 9th century, and has seen little additional in-migration since. Even today, more than 90 percent of Iceland’s 390,000 residents can trace their ancestry back to the earliest permanent inhabitants, a Nordic-Celtic mix. The tradition of the Norse sagas lives on in the form of careful record-keeping about ancestry—and a national passion for genealogy. In other words, it is not the place to stumble upon old family mysteries. But growing up in the capital city of Reykjavík in the 1950s, neurologist Dr. Kári Stefánsson heard stories that left him curious. Stefánsson’s father had come from Djúpivogur, an eastern coastal town where everyone still spoke of a Black man who had moved there early in the 19th century. “Hans Jónatan”, they called him—a well-liked shopkeeper who had arrived on a ship, married a spirited woman from a local farm, and became a revered member of the community. The local census did record a man by the name of Hans Jónatan, born in the Caribbean, who was working at the general store in Djúpivogur in the 19th century—but that was all. No images of the man had survived, and his time in Iceland was well before any other humans with African ancestry are known to have visited the island. If tiny, remote Djúpivogur did have a Black man arrive in the 19th century, the circumstances must have been unusual indeed. It was an intriguing puzzle—and solid grounds for a scientific investigation. Given the amount of homogeneity in the baseline Icelandic population, the genetic signature of one relative newcomer with distinct ancestry might still stand out across a large sample of his descendants. Geneticists thus joined locals and history scholars, and they pieced together a story that bridged three continents. Continue reading ▶

It’s been a busy summer, and the large shortfall in donations last month has been demoralizing, so we’re taking a week off to rest and recuperate. The curated links section will be (mostly) silent, and behind the scenes we’ll be taking a brief break from our usual researching, writing, editing, illustrating, narrating, sound designing, coding, et cetera. We plan to return to normalcy on the 11th of September. (The word “normalcy” was not considered an acceptable alternative to “normality” until 14 May 1920, when then-presidential-candidate Warren G. Harding misused the mathematical term in a campaign speech, stating that America needed, “not nostrums, but normalcy.” He then integrated this error into his campaign slogan, “Return to Normalcy.” Also, the G in Warren G. Harding stood for “Gamaliel.”) While we are away, on 06 September 2023, Damn Interesting will be turning 18 years old. To celebrate, here are the first emojis to ever appear in the body of a Damn Interesting post: 🎂🎉🎁 If you become bored while we are away, you might try a little mobile game we’ve been working on called Wordwhile. It can be played alone, or with a friend. If you enjoy games like Scrabble and Wordle, you may find this one ENJOYABLE (75 points). Launch Wordwhile → And, as always, there are lots of ways to explore our back-catalog. View this post ▶

In the late 17th century, natural philosopher Isaac Newton was deeply uneasy with a new scientific theory that was gaining currency in Europe: universal gravitation. In correspondence with a scientific contemporary, Newton complained that it was “an absurdity” to suppose that “one body may act upon another at a distance through a vacuum.” The scientist who proposed this preposterous theory was Isaac Newton. He first articulated the idea in his widely acclaimed magnum opus Principia, wherein he explained, “I have not yet been able to discover the cause of these properties of gravity from phenomena and I feign no hypotheses […] It is enough that gravity does really exist and acts according to the laws I have explained.” Newton proposed that celestial bodies were not the sole sources of gravity in the universe, rather all matter attracts all other matter with a force that corresponds to mass and diminishes rapidly with distance. He had been studying the motions of the six known planets–Mercury, Venus, Mars, Jupiter, Saturn, and Uranus–and by expanding upon the laws of planetary motion developed by Johannes Kepler about eight decades earlier, he arrived at an equation for gravitational force F that seemed to match decades of data: Where m1 and m2 are the masses of the objects, r is the distance between their centers of mass, and G is the gravitational constant (~0.0000000000667408). But this is only an approximation; humanity may never know the precise value because it is impossible to isolate any measuring apparatus from all of the gravity in the universe. Fellow astronomers found that Newton’s theory seemed to be accurate–universal gravitation appeared to reliably forecast the sometimes irregular motion of the planets even more closely than Kepler’s laws. In 1705, Queen Anne knighted Isaac Newton to make him Sir Isaac Newton (though this honor was due to his work in politics, not for his considerable contributions to math or science). In the century that followed, Newton’s universal gravitation performed flawlessly. Celestial bodies appeared to adhere to the elegant theory, and in scientific circles, it began to crystallize into a law of nature. But in the early 19th century, cracks began to appear. When astronomer Alexis Bouvard used Newton’s equations to carefully calculate future positions of Jupiter and Saturn, they proved spectacularly accurate. However, when he followed up in 1821 with astronomical tables for Uranus–the outermost known planet–subsequent observations revealed that the planet was crossing the sky substantially slower than projected. The fault was not in Bouvard’s math; Uranus appeared to be violating the law of universal gravitation. Newton’s theory was again called into question in 1843 by a 32-year-old assistant astronomer at the Paris Observatory, Urbain Le Verrier. Le Verrier had been following the Uranus perturbations with great interest, while also compiling a painstaking record of the orbit of Mercury–the innermost known planet. He found that Mercury also departed from projections made by universal gravitation. Was universal gravitation a flawed theory? Or might undiscovered planets lurk in extra-Uranian and intra-Mercurial space, disturbing the orbits of the known planets? Astronomers around the world scoured the skies, seeking out whatever was perturbing the solar system. The answer, it turned out, was more bizarre than they could have supposed. Continue reading ▶

An American Indian man on horseback stood outlined against a steely sky past midday on 05 October 1877. Winter was already settling into the prairies of what would soon become the state of Montana. Five white men stood in the swaying grass on the other side of the field, watching the horse move closer. Four wore blue uniforms, another in civilian attire. One of the uniformed men was tall and stout, with bright blue eyes and a large, curling mustache. He watched the proceedings with an air of self-importance. The surrender of the man on horseback might have been inevitable, sure, but it was nevertheless a nice feather in his cap. Perhaps his superiors would finally grant him that promotion after this whole affair was over. The other four men were more apprehensive. All of them were experienced in fighting American Indians on the frontier, but this opponent had been different. One man, with a full, dark beard and right arm missing below the elbow, looked at the approaching chief with grudging respect. The man had lost his arm in the American Civil War 15 years earlier, so he knew battle well. And in his opinion, the man across the field was a tactical genius, a “Red Napoleon.” Despite overwhelming odds, this Red Napoleon had wormed his way out of battle after battle, somehow always coming out on top. Continue reading ▶