Biology

Aristotle wrote about eels in Historia Animalium around 350 BCE. He observed that they had no testes, no ovaries, no obvious reproductive organs of any kind. He concluded — reasonably, given what he could see — that eels must arise spontaneously from mud. Specifically, from the entrails of the earth. This was wrong. Twenty-three hundred years later, we know it’s wrong. We also still cannot reliably explain, in much detail, how eels reproduce....

The Grip That Never Was I used to think my fingerprints were nature’s grip tape. Those intricate ridges spiraling across my fingertips — surely they were there to help me hang onto things, right? Like treads on a tire, or the ridged soles of hiking boots. It’s such an obvious explanation that for over a century, it was simply accepted fact. Except when someone finally bothered to measure it properly, fingerprints turned out to make your grip worse....

The Blind Fish That Didn’t Rewire Its Brain Everything I thought I knew about blind cavefish was wrong — or at least, built on a metaphor that turns out to be misleading. Here’s the story as it’s usually told: Astyanax mexicanus, the Mexican tetra, has populations that wandered into limestone caves hundreds of thousands of years ago, lost their eyes, and “repurposed” the brain tissue that would have processed vision for other senses....