One hundred and sixty-five million years before a human ear could have been present to hear it, insects were already singing in frequencies beyond human perception. Researchers have now reconstructed those ancient songs from fossilized wing fragments using lasers, machine learning, and evolutionary modeling, discovering that ultrasonic communication existed long before the bats long blamed for driving it. The finding invites us to reconsider how life shapes its own sensory world not in response to a single predator, but through a web of pressures — competition, concealment, and the crowded aco
Scientists Reconstruct 165-Million-Year-Old Insect Calls, Challenging Bat Evolution Theory
Bats emerged into a soundscape already busy with ultrasounds
Mark
How do you actually extract sound from a fossil? There's no recording, no vibration left in the rock.
Mimi
You don't extract sound directly. You measure the physical structures that made the sound. The ridges on a cricket's wing—the file and plectrum—are like the grooves on a record. Measure them precisely, understand how they would vibrate, and you can predict the frequency and tone.
Mark
So you're reconstructing, not recovering. That's a big difference.
Mimi
Exactly. But it's not guesswork. They used laser measurements of living insects' wings, compared the fossils to modern species to understand the evolutionary relationships, ran computer simulations. Machine learning trained on living insects helped predict what calls those ancient wing shapes would produce.
Mark
And they found ultrasound in the Jurassic. That's the surprise.
Mimi
Yes. Bats didn't show up until fifty-five million years ago. But these insects were already calling at frequencies above twenty kilohertz. So the whole story about bats driving insects into ultrasound—that's incomplete.
Mark
What was actually driving them, then?
Mimi
That's the open question now. Early mammals hunting by sound. Acoustic crowding—too many insects calling at the same frequencies, so they spread out into different niches. Maybe both. The point is that evolution is messier than we thought. Bats didn't invent ultrasonic communication. They inherited a world already full of it.
El Pulso
- A foundational assumption in evolutionary biology — that bats drove insects into the ultrasonic range — has been overturned by evidence 100 million years older than bats themselves.
- Twenty fossilized insects from Inner Mongolia, their wing ridges preserved in stone, became the unlikely archive of a Jurassic soundscape no living creature has ever heard.
- Researchers combined laser vibrometry, phylogenetic comparison across nearly a hundred living species, computer simulation, and machine learning to decode what those ancient wings once sang.
- One species, Sigmaboilus peregrinus, called at ultrasonic frequencies — a discovery that forces scientists to look toward early mammals and inter-species acoustic competition as the true architects of high-frequency insect communication.
- The study, published in PNAS, repositions bats not as the creators of an ultrasonic world, but as latecomers to a soundscape already rich with signals they did not invent.
One hundred and sixty-five million years before a human ear could have been present to hear it, insects were already singing in frequencies beyond human perception. Researchers have now reconstructed those ancient songs from fossilized wing fragments using lasers, machine learning, and evolutionary modeling, discovering that ultrasonic communication existed long before the bats long blamed for driving it. The finding invites us to reconsider how life shapes its own sensory world not in response to a single predator, but through a web of pressures — competition, concealment, and the crowded acoustics of a living forest.
A team led by Jun-Jie Gu of Sichuan Agricultural University has reconstructed the acoustic calls of insects that lived 165 million years ago — a feat made possible not by any surviving vocal anatomy, but by the fossilized wing structures insects use to produce sound. Male crickets and their relatives stridulate by rubbing one wing against the other, and the microscopic ridges that enable this process are preserved in exoskeleton fossils. In effect, the stone holds the song.
The researchers examined twenty fossilized insects from the Jiulongshan Formation in Inner Mongolia, representing nine species from two extinct Middle Jurassic families. They measured the wing structures of living relatives using laser vibrometry, mapped evolutionary relationships across nearly a hundred modern species, ran simulations of how the ancient wings would have vibrated, and trained machine-learning models to predict the resulting calls. What emerged was a portrait of a diverse and active ancient soundscape.
Most species produced low-frequency calls around five kilohertz, consistent with modern crickets. But one species, Sigmaboilus peregrinus, appears to have called at ultrasonic frequencies — above twenty kilohertz — roughly one hundred million years before bats evolved. This dismantles the long-held theory that bat predation was the primary evolutionary pressure pushing insects into the ultrasonic range.
The researchers propose a more layered explanation: early mammals may have hunted by sound long before bats appeared, and the sheer acoustic density of Jurassic forests likely pushed species to carve out distinct frequency niches. The variety of call types already present — pure tones, high-pitched signals, variations in pitch and duration — suggests insects were diversifying their acoustic strategies well before any echolocating predator existed to select for them. Bats, it now appears, inherited an ultrasonic world they did not create.
A team of paleontologists has done something that seemed impossible: they have listened to insects sing from 165 million years ago. Using fossilized wing fragments pulled from rocks in Inner Mongolia, combined with lasers, computer models, and artificial intelligence, researchers led by Jun-Jie Gu of Sichuan Agricultural University reconstructed the acoustic calls of ancient relatives of crickets and katydids. What they heard rewrites a fundamental assumption about how insects evolved to communicate at frequencies beyond human perception.
The work hinges on a simple fact of paleontology: while the vocal cords of dinosaurs and other vertebrates rarely survive fossilization, the sound-producing structures of insects do. Male crickets and their relatives create sound by rubbing one wing against the other—a process called stridulation—and the microscopic ridges and teeth that make this possible are etched into the insect's exoskeleton. These structures fossilize. They leave behind, in effect, a physical record of the songs they once made.
The researchers examined twenty fossilized insects from the Jiulongshan Formation, representing nine species from two extinct families that lived during the Middle Jurassic period. They combined several analytical techniques: they measured the wing structures of modern insects using laser vibrometry, compared the fossils to nearly a hundred living species to understand evolutionary relationships, ran computer simulations of how the ancient wings would have vibrated, and trained machine-learning algorithms to predict what calls those wing shapes would have produced. The result was a map of an ancient soundscape, diverse and complex.
Most of the nine species produced low-frequency calls around five kilohertz, similar to modern crickets. But one species, Sigmaboilus peregrinus, appears to have called at frequencies above twenty kilohertz—ultrasonic, inaudible to human ears. This finding carries enormous weight because it predates the emergence of bats by roughly one hundred million years. Bats, which appeared about fifty-five million years ago, have long been credited as the evolutionary pressure that pushed insects into the ultrasonic realm. The theory was straightforward: insects evolved high-frequency calls to evade echolocating predators. But if insects were already using ultrasound in the Jurassic, that narrative breaks apart.
The researchers propose instead that multiple forces shaped the evolution of insect communication. Early mammals, long before bats, may have hunted by sound and driven insects to develop quieter, harder-to-locate calls. Acoustic competition among many calling species in crowded Jurassic forests may have pushed insects to carve out their own frequency niches. The diversity of call types—pure tones, high-pitched signals, variations in pitch and duration—suggests insects were already experimenting with different acoustic strategies millions of years before bats existed to select for them.
The paper, published in the Proceedings of the National Academy of Sciences, frames this as evidence that bats did not single-handedly drive the evolution of ultrasonic communication in insects. Instead, bats emerged into a soundscape already thick with ultrasonic signals. The ancient forests of the Jurassic were not silent. They hummed and chirped and whistled at frequencies that no ear alive today can hear. Understanding that world—reconstructing it from stone and mathematics—opens a new window onto how life adapts and diversifies under pressure, and how the sensory world itself evolves across deep time.
Citas Notables
Ultrasonic communication was likely adopted by katydid ancestors during the Middle Jurassic, some 165 million years ago, the oldest record known for ultrasound communication in animals.— Jun-Jie Gu and colleagues, Proceedings of the National Academy of Sciences
We reject the hypothesis that bats were the sole driver of ultrasound evolution in katydids. Instead, it is likely that early mammals and non-mammalian ancestors were also listening in to the songs of ensiferans.— Jun-Jie Gu et al.
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