For over 80 years, scientists have been trying to resolve a great mystery: Why can’t humans walk straight? Without a visible guidepoint like the sun or the moon or a mountain top in sight, we seem to go around in circles — quite literally. Here, NPR correspondent Robert Krulwich distills decades of inconclusive research, with the help of animator Benjamin Arthur.

There are countless experiments throughout history to test this curious quirk.

In 1920s, a young scientist asked a friend to walk across a field in a straight line, blindfolded. But here’s what the friend did:

In 1928, three men left a barn on a very foggy day and set out to walk to a point a mile away, straight ahead. Instead, this is how their journey went:

Also in 1928, a man was blindfolded, then asked to jump into a lake and swim straight to the other side. Here’s what he ended up doing:

When a man was asked to get in a car and drive straight across an empty Kansas field, he did the following:

There is, apparently, a profound inability in humans to stick to a straight line when blindfolded.” ~ Robert Krulwich

And while this particular mystery might not yet have an answer, on the subject of fascinating factoids from the folks at NPR, don’t forget the excellent All Facts Considered — an answers-laden compendium of curiosities from NPR’s endearing, librarianly librarian.