The science of handedness is going through a bit of a renaissance right now. Just in the past few months, researchers have uncovered more about why roughly 90 percent of humans are right-handed and have come up with theories that suggest that handedness may depend more on practice than genetics. Researchers have even come up with ways that you can determine your dog’s handedness.
Now, according to research published in Scientific Reports and covered by The New York Times, a completely different team has pushed the origins of handedness back another half-billion years by identifying what may be the oldest right-handed animal ever discovered.
The fossil once belonged to a small wormlike critter called a Spriggina that lived about 550 million years ago during the Ediacaran Period. That’s way before the dinosaurs and even before complex animal life exploded across the planet. To the untrained eye, its imprint would look like a small palm tree branch fell into some wet cement, but this fossil, along with more than 100 fossils found in South Australia, helped researchers determine that about twice as many of the preserved animals seem to have curved to the right, suggesting that the right was their dominant side, meaning that these otherworldly creatures were right-handed.
Right-Handed Before There Were Hands to Write
Or right… legged? Because the Spriggina didn’t have hands. Regardless, the fossil record suggests it consistently favored one side of its body while moving across the seafloor. There were other possible explanations that the research team had ruled out, like that ocean currents possibly influenced the fossil and that the bodies curled up after death, making it seem like they favored one side over another. But the team found that the fossils preserved animals in different positions and orientations, which means that they were moving under their own control and, thus, any evidence suggesting that they were favoring one side over another was an accurate indicator of handedness.
If this does indeed turn out to be the case, then it means the Spriggina likely had a primitive nervous system that made it able to coordinate muscles that could control directional behavior, meaning it had already evolved a preference for turning one way or the other.
We tend to view handedness through the prism of humanity, but the more we dig through the fossil record, the more we learn that preference for one side of our body or another didn’t start with us, and it didn’t even start with hands.
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