550-million-year-old fossil reveals the evolutionary origin of being right- or left-handed
要点
- By examining 550-million-year-old Spriggina floundersi fossils, researchers found the oldest known evidence of behavioral bias (right-left preference).
- It was determined that this primitive marine creature, which had no arms or legs, showed a tendency to bend its body to the right and preferred to turn right.
- The study, which examined more than 100 fossils found in Australia, confirmed the results by eliminating the influence of ocean currents or anatomical asymmetry.
数据一览
The habit of using the right or left hand is not unique to humans; today, a tendency to prefer one side of the body is seen in many creatures, from kangaroos to chimpanzees. Scientists have discovered that the history of these behavioral traits dates back much further than previously thought, to 550 million years ago. This finding was obtained by examining fossils of the Spriggina floundersi species, one of the first known animals to have a head and bilateral symmetry.
In the study published in the journal Scientific Reports, more than 100 fossils found in the Güney region of Australia were examined in detail. It was determined that this tiny creature, which lived on the seafloor during the Ediyakaran period and had no arms or legs, showed a tendency to turn to the right when bending its body. Confirming that this situation was not caused by ocean currents or the fossilization process, researchers accepted the phenomenon as a behavioral bias.
This discovery indicates that even in the early stages of the evolution of bilaterally symmetrical organisms, the nervous system might have possessed a certain directional organization. It is thought that the creature needed muscles and a primitive nervous system to coordinate its different movements. However, scientists have not yet been able to fully determine why this side preference emerged or what function it served.
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常见问题
- Exactly when and where did the fossilized creature in question live?
- The creature named Spriggina floundersi lived on the seafloors of the Güney region of Australia during the Ediyakaran period (more than 550 million years ago), the period before the Cambrian explosion.
- How can a creature without feet and arms be 'right-handed' or 'left-handed'?
- There is no question of hand or foot usage in these creatures; the bias manifests itself as a statistical tendency regarding whether the animal bends its body to the right or to the left while moving on the seafloor.
- How did scientists make sure that this bend was a bias?
- Seeing that the fossils on the same surface bent in different directions and that there was no common directional tendency, they decided that this situation was a behavioral preference rather than a result of ocean currents, the fossilization process, or anatomical structure.