Researchers have reconstructed the sounds of insects from 165 million years ago, offering a sonic glimpse into the Jurassic period. By examining fossilized insect wings, scientists have recreated eerie calls ranging from cicada-like chirps to ultrasonic frequencies, which likely helped these creatures communicate and evade predators.
The study, which analyzed 20 fossils from nine species found in China's Inner Mongolia region, focused on ancient ancestors of modern grasshoppers and katydids. These insects produced sound through a process called stridulation, rubbing parts of their bodies together. The sound-producing structures, microscopic teeth-like ridges on their wings, are often well-preserved in fossils.
Scientists scanned these ridges under microscopes to create detailed models of the wings. These models were then fed into computer simulations, along with data from modern insects, to estimate the sound frequencies and call rates. The team used lasers to measure wing vibrations in contemporary insects and employed a machine learning model to reconstruct the ancient calls.
Lead author Dr. Fernando Montealegre-Zapata, an entomologist at the University of Lincoln, noted that the findings suggest Jurassic environments were far from silent, filled instead with a variety of sounds. "Hearing the first reconstructed call was fascinating," he stated. "It revealed that the way these insects produce sound has changed remarkably little since the Jurassic period."
Some reconstructed calls produced pure tones, similar to musical notes, concentrating their energy in a narrow frequency band. These sounds, resembling high-pitched beeps or squeaks, travel effectively through crowded, nocturnal soundscapes. Dr. Montealegre-Zapata explained that this specialization likely allowed insects to be heard by mates while making it harder for predators to locate them.
Remarkably, one species, Sigmaboilus peregrinus, appears to have produced ultrasonic calls above 20 kHz, beyond human hearing. This predates the common theory that such calls evolved as a defense against bats, suggesting ultrasound communication emerged earlier as an evolutionary arms race between insects and predators. As predators improved their auditory detection, insects shifted their calls to higher frequencies, eventually into the ultrasonic range.
This suggests that mammals in the Jurassic period may have already been developing sensitivity to ultrasound, potentially over 100 million years before bats became widespread. "Rather than introducing ultrasound to a quiet environment, bats may have entered a soundscape that was already filled with ultrasonic signals," Dr. Montealegre-Zapata commented. "In that sense, the Jurassic was not only noisier than we once imagined, but also acoustically more sophisticated."
The recreated sounds were even used in the soundtrack for the Netflix documentary series The Dinosaurs. The research highlights how well-preserved insect fossils can unlock acoustic information about ancient ecosystems, painting a richer picture of prehistoric life.