For decades, the search for extraterrestrial intelligence (SETI) has largely operated on the assumption that if aliens are trying to contact us, they will probably use signals that resemble our own technology. This has meant looking for unusual radio transmissions and, more recently, optical laser signals. However, what if an alien civilization communicates in a way that is nothing like human technology? A new study suggests we may be overlooking an entirely different approach to finding extraterrestrial signals, one inspired by the flashing patterns of fireflies. Rather than trying to understand what an alien message says, scientists propose looking for a signal that stands out from its natural surroundings.“The Search for Extraterrestrial Intelligence (SETI) has historically been a search for aliens like us, shaped by human-centric ideas of intelligence, communication, and technology. However, humans are not the only instance of an intelligent, communicating species on Earth, and thus not the only guide to how we might think about ETI,” the study authors note.What fireflies can teach us about alien communicationThe problem with conventional SETI strategies is that they tend to search for signals that humans recognize as potentially intelligent. Yet intelligence and communication do not necessarily have to follow human patterns. On Earth, animals such as dolphins, crows and fireflies communicate in ways that are very different from ours.Fireflies offer a particularly interesting example. During mating season, these insects use sequences of flashes to attract potential partners. Their signals vary in timing, duration, color and repetition rate, helping them distinguish themselves from other fireflies flashing nearby. Producing these flashes also costs energy and can attract predators, giving the insects reasons to make their signals both distinctive and economical.Inspired by this behavior, researchers developed a simplified mathematical model to explore how an extraterrestrial civilization might make its transmissions recognizable against the natural signals already present in space.They drew on earlier research examining how firefly mating signals could evolve to become more distinguishable from competing signals in a crowded environment while conserving energy. They applied the same underlying idea to astronomy where an artificial signal might not need to be complicated if its structure makes it noticeably different from the natural activity around it.“Our model demonstrates that alien signals need not be inherently complicated nor must we decipher their meaning to identify them; rather, signals might be distinguishable as products of engineering or evolutionary design,” the study authors added.Making an alien signal stand out from pulsarsFor their model, the researchers turned to pulsars, rapidly rotating, highly magnetized neutron stars that emit regular beams of radiation. As these beams sweep across Earth, they appear as remarkably consistent pulses. Their regularity makes them interesting candidates for comparison because a deliberately transmitted alien signal could potentially resemble a pulsar’s emissions.The researchers used data from 3,724 pulsars in the Australia Telescope National Facility database to generate simulated radio-pulse patterns. They converted the pulsar profiles into simple binary sequences, assigning a value of 1 when the measured radio brightness exceeded a selected threshold and 0 when it fell below it.For their main experiment, they selected 158 pulsars located within five kiloparsecs, or approximately 16,000 light-years, of Earth. These formed the natural astronomical background against which hypothetical alien transmissions would have to stand out. The selected pulsars had mean flux densities above 1 millijansky (mJy) at 1,400 megahertz, the frequency used in the main test. This frequency is close to the famous 1,420-MHz hydrogen emission line. Radiation at this wavelength, around 21 centimeters, can penetrate interstellar dust clouds, making it useful for astronomical observations and a potential choice for extraterrestrial broadcasting.The model then generated repeating radio-pulse patterns designed to be as different as possible from the surrounding pulsar signals while minimizing energy consumption. It focused on two properties: the period between repeating pulses and the fraction of each period during which the signal remained switched on, known as its absolute duty cycle. The researchers also accounted for differences in the timing, or phase, of incoming pulsar signals. The optimization produced two signal structures: one that prioritized maximum distinctiveness without considering energy costs, and another that balanced distinctiveness with the energy required to transmit. The latter treated the fraction of time a signal remained switched on as a measure of its energy cost. The resulting approach suggests that an artificial signal could be recognizable without being particularly complex or carrying a message that humans could decipher.Finding intelligence before understanding itThe study offers a different way to think about the search for extraterrestrial intelligence. Instead of assuming that alien civilizations must communicate through elaborate messages, scientists could first look for signals whose patterns appear deliberately different from their natural surroundings.However, this remains a conceptual demonstration, not a system that has discovered an extraterrestrial transmission. Converting continuous pulsar profiles into simple on/off sequences also discards finer details that could contain useful information. Moreover, an unusual signal is not necessarily artificial, so the approach would need to distinguish engineered patterns from naturally occurring ones in real astronomical observations, an ongoing challenge for radio telescopes searching for extraterrestrial technology.“This would complement, not replace, existing SETI methods,” the researchers note. Their broader message is that scientists may need to look beyond familiar forms of technology and consider the fundamental properties that make a signal recognizable as artificial. After all, an alien civilization might not need to send us a complicated message to announce its presence. It might simply need to stand out.The study is published in the journal Scientific Reports.