Scientists have discovered what may be the earliest evidence of right-handedness in the animal kingdom, dating back over 550 million years. This groundbreaking finding, published on July 9, 2026, in Scientific Reports, centers on the fossil of Spriggina floundersi, an organism from the Ediacaran Period, excavated in South Australia.
Discovery of Right-Handedness in Early Animals
The research team, led by scientists from the American Museum of Natural History, Florida State University, Harvard University, and the University of California, Riverside, indicates that Spriggina exhibited a consistent preference for bending to the right. This revelation suggests that behavioral preferences associated with one side of the body emerged far earlier in evolutionary history than previously recognized.
Lead author Scott Evans, assistant curator of invertebrate paleontology at the museum, stated, "When we talk about being right- or left-handed, most people likely think about how they hold a pencil or kick a soccer ball. But our research shows that an animal without hands or feet, living over 500 million years ago, may have had its own version of handedness."
Significance of the Ediacaran Period
The Ediacaran Period, spanning from approximately 635 to 538 million years ago, is a notable chapter in the history of life on Earth. During this time, microscopic life evolved into multicellular organisms, leading to increasingly complex behaviors, including movement. The Flinders Ranges in South Australia preserve one of the most exceptional records of this fossil assemblage.
Excavations at Nilpena Ediacara National Park reveal communities of the Ediacara biota, which were buried during storm events, capturing snapshots of the seafloor from 550 million years ago. Among these fossils is Spriggina, recognized as one of the earliest known animals with bilateral symmetry—a body plan shared by humans and most animals today.
Research Findings and Implications
To investigate the left-right preference in Spriggina, researchers examined shape variation in over 100 exceptionally preserved fossils. The team discovered that roughly twice as many specimens were bent to the left compared to the right. This consistent pattern indicates that Spriggina preferentially turned to the right, marking it as the oldest known animal to display population-wide handedness.
Co-author Mary Droser, a paleontologist at the University of California, Riverside, remarked, "It's a reminder that some of the traits we take for granted today have incredibly ancient origins." The discovery also provides insights into how Spriggina might have perceived its environment, suggesting a relatively complex nervous system akin to that of modern animals.
- Research led by American Museum of Natural History
- Fossil dating back 550 million years
- Indication of early animal handedness
- Implications for understanding evolution of sensory abilities
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