Forget everything you know about dexterity. Or rather, remember it. You favor the right hand, the rest of humanity likely does too. 85 percent to 90 percent. It is not an accident. It is a legacy. One that stretches back five hundred fifty million years.
“The dominance of bends to the left in suggests a preference for right turns…”
Scientists looked at fossils. Not bones, but impressions in rock. From South Australia. From a place called Nilpena Ediacara. They studied Spriggina floundersi. A worm-like creature. An inch long. Wriggling around in the mud of the Ediacaran period.
They found over a hundred of these ghosts in the stone. Almost all of them curved to the left. Think about the mirror image of that. A left-curving fossil means a right-turning animal in life. These creatures turned right. Consistently.
It is the oldest known evidence of handedness in any animal. Ever.
Trapped in Stone
Spriggina was not just goop. It had a front. A back. A top. A bottom. Bilateral symmetry. Just like you. Just like me. It could move. Complex movement for the time. The Ediacaran was a weird era. The first multicellular things anyone could actually see with their own eyes appeared then.
This isn’t about holding a pen. It is deeper. Much deeper. Scott Evans, the guy who led the study, said it plainly. An animal without hands, without feet, had its own version of sidedness. Half a billion years ago.
The fossils were buried by a storm. Preserved for half a millennium. It seems abrupt, that kind of luck. A flash flood turning a wriggling worm into data.
Is It Genetic?
So why are we all right-handed?
Partly genes. Forty different genes might play a part. The preference starts in the womb. Fetuses show a thumb-sucking bias before they even blink.
But culture gets in the way. Some places thought left-handedness was unclean. Worse than unclean, really. Satanic. Parents forced their kids to use the right hand. Scissors cut from the right. Scissors made for right-handed people.
Still, the bias remains. Why? Maybe it’s random mutations during brain development. Maybe not. Left-handed people are a minority. That’s a disadvantage in a right-world. It can be an advantage in combat, though. Tennis pros like Rafael Nadal switched hands for the edge.
Spriggina had no sports to play. No pencils. Yet the bias was there.
Four hundred eighty million years separate that worm from our ancestors. That’s a lot of evolutionary time. But the thread holds. We might not be the innovators of our own dexterity. Just the inheritors.
Does that make the choice any less free? Or just more ancient?
The rock says yes. The rock does not say why.
