Why did some discoveries take so much longer than others?

From Adam Mastroianni at Experimental History: "There's something very weird about the timeline of scientific discoveries. For the first few thousand years, it’s mostly math. The Greeks had the beginnings of trigonometry by ~120 BCE. Chinese mathematicians figured out the fourth digit of pi by the year 250. In India, Brahmagupta devised a way to “interpolate new values of the sine function” in 665. Meanwhile, we didn't discover things that seem way more obvious until literally a thousand years later. It's not until the 1620s, for instance, that English physician William Harvey figured out how blood circulates through animal bodies by, among other things, spitting on his finger and poking it into the heart of a dead pigeon. We didn't really understand heredity until Gregor Mendel started gardening in the mid-1800s, and we didn't really grasp the basics of learning until Ivan Pavlov started feeding his dogs in the early 1900s."

The MacArthur Genius who discovered that COVID transmission was airborne

From Gabriel Spitzer for NPR: "To understand why the MacArthur Foundation singled out Linsey Marr for one of this year's fellowships – the so-called "genius grants" –  you have to go back to the first days of the COVID-19 pandemic. The early guidance from health experts emphasized washing hands and keeping six feet from others with no recommendation to wear masks or avoid gathering indoors. Linsey Marr, an aerosols expert and professor of civil and environmental engineering at Virginia Tech, became convinced that advice was based on a flawed idea of how respiratory viruses spread. Her groundbreaking research and tireless advocacy showed that the virus is airborne as opposed to traveling in large droplets that fall with gravity. That work helped lead to a course correction in the public health guidelines and likely saved lives."

What can archaeology tell us about what the Druids were really like?

From Miranda Aldhouse-Green at Aeon magazine: "Gaius Verius Sedatus was a respectable citizen of the community of Chartres in the early 2nd century CE. He was a member of his local town council (a sort of mini-senate), where he and his colleagues presided over its laws and management, under the aegis of Roman law. Gaul had been conquered by Julius Caesar two centuries earlier and was now administered by trusted locals such as Sedatus, overseen by distant Roman officials. But Sedatus lived a double life. In the evening, he donned the mantle of a magician-priest and descended to his underground temple in the small cellar of his house. There he kept a group of four large incense-burners, placed symmetrically at the points of a square. He filled these vessels with aromatic, perhaps hallucinogenic herbs, and lit fires beneath them."