Smithsonian Magazine · Geschiedenis en cultuur

Scientists Recreated the Long-Lost Chirps of Jurassic Insects

Scientists have recreated the sounds of Jurassic insects from 165 million years ago using fossil analysis and AI. These simulated soundscapes reveal that the Jurassic period was acoustically richer than previously thought and challenge existing theories on insect sound evolution.

The Jurassic period's soundscape included chirps from cricket-like insects, some too high-pitched for humans to hear. Scientists analyzed 165-million-year-old insect fossils, focusing on wing structures and using AI to reproduce their sounds. This research, published in the Proceedings of the National Academy of Sciences, suggests the Jurassic world was acoustically more diverse than believed.

Unlike vocal cords, insect legs and wings can fossilize, preserving the "instruments" they use to produce sound through stridulation (rubbing body parts together). Scientists examined 20 fossilized insects from Inner Mongolia, belonging to nine species related to crickets and katydids, to understand their calls.

By analyzing the ridged features on the fossilized wings and comparing them with modern insects' stridulation mechanics, researchers simulated the vibrations and pitches of prehistoric insect calls. An AI model predicted the call patterns based on the fossilized wing shapes.

Most of these ancient insects likely produced low-frequency, pure-tone calls around five kilohertz, similar to modern crickets. However, one species, Sigmaboilus peregrinus, appears to have produced ultrasonic chirps between 20 and 22 kilohertz, a frequency beyond human hearing.

The discovery of ultrasonic chirps in S. peregrinus, which lived before bats, challenges the idea that bats were the sole drivers of ultrasonic call evolution in insects. The study suggests that predation by a broader range of mammals and non-mammals, or the need to stand out in a noisy environment, may have led to the evolution of higher-pitched insect sounds.

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