Fossils of an ancient sea creature are the oldest evidence of right-handedness

by | Jul 9, 2026 | Science

If you happen to be right-handed, you may be able to trace the origins of that trait to a wormlike animal that lived about 550 million years ago and had a tendency to bend to the right.Spriggina floundersi appeared in oceans during the Ediacaran Period (635 million to 542 million years ago) at the dawn of the first forms of animal life.The small creature’s flat, segmented body, known only from fossils found in what’s now South Australia, was a stretched-out oval. It tapered to a tip at one end and had a large, curved structure at the other, making it the earliest known animal with a head.AdvertisementAdvertisementPaleontologists described the first Spriggina fossils in 1958. Since then, scientists have debated whether the animal could move on its own. To answer that question, researchers recently examined more than 100 fossils in the most comprehensive analysis of Spriggina since its discovery.The scientists concluded that not only did Spriggina wriggle across the seafloor, but the abundance of fossil specimens curving left meant that these early animals favored their right sides, a behavioral preference seen in modern animals that are right-handed.No animal quite like Spriggina exists today, but it set the evolutionary stage for directional preference, a trait possessed not only by most humans but also by other primates, mice , frogs and insects.”Fossils of early animals, to most people — even to me — they look weird,” said Scott Evans, lead author of the study detailing the findings that published Thursday in the journal Scientific Reports. But if you push past that weirdness, “what we see is that a lot of the fundamental characters that we associate with animals today, things like the ability to move and even having this behavioral handedness, are present in these earliest animal communities.”A ‘really surprising’ discoveryIn some of the fossils, the bodies were straight, while others were curved. The fossils were mirrored imprints of the animals’ soft bodies. Most bent left in the roc …

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