This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When we think of extraterrestrial intelligence that might be out there among the stars, we tend to think of creatures not too unlike us, though maybe with gray skin, probably bald and with big black eyes. We focus on the familiar, humanoids.
But there are many intelligent species on Earth that are nonhumanoid: dolphins, crows, pigs and—with swarm if not individual intelligence—ants and bees. The film "Arrival" conceived of hexapod beings more capable than humans and with a more sophisticated communication system. Searches for extraterrestrial signals also mostly look for the currently familiar, primarily radio signals, the kind that we have been emitting for a hundred years.
Since 2016, the Breakthrough Listen initiative has also been looking for optical laser transmissions. Our transition to cable TV and the internet leaves Earth less "radio loud," and any aliens might have gone through a similar short period of radio activity. This suggests "new paradigmatic frameworks could be necessary to recognize intelligent alien signals in astronomical data," write a group of American scientists in the journal Scientific Reports.
Making note of the Earth Species Project, where scientists are using machine learning to study animal communication, the researchers, from universities in the southwestern United States, developed a toy model—a simplified representation of a complex system designed to focus on the most essential features—of signal detectability inspired by fireflies. In mating season, fireflies, also known as lightning bugs, glowworms, candle flies or fire beetles, produce sequences of flashes, usually during twilight, by the chemical process of bioluminescence produced from a specialized light-emitting organ located on their abdomens. Their purpose is mating, as flying males reveal themselves to females on the ground.
The flashing patterns can be altered in duration of luminescence, timing, color, the number and the rate of repetitions, the height of emission and the direction of flight. They vary by species as well as by geography. The scientists, with lead author Cameron Brooks of Arizona State University, utilized a 2022 paper by Chantal Nguyen, and others, that investigated how firefly mating signals might co-evolve amidst the visual chaos of a swarm of fireflies, while maximizing the distinctiveness from other firefly species and limiting flashing to conserve energy. (Flashes require energy from the firefly and also pose a risk from predators.) The researchers developed a toy model that evolved an alien signal that is "maximally distinct from a background of highly ordered, naturally occurring signals generated by pulsars, while also minimizing energy consumption." Pulsars are highly magnetized, rapidly spinning neutron stars that produce bright, regular emissions in a highly periodic beam sweeping across space.
There are an estimated 100,000 in the Milky Way galaxy, and, if the beam sweeps across the plane of Earth's orbit, they are detectable by us. These properties are what might be expected of the broadcasts of an alien intelligence. (In fact, when pulsars were discovered in 1967, their behavior was so odd it was speculated they might be broadcasts by extraterrestrials.) Any intelligent aliens looking to broadcast their location with a pulsed radio beam would presumably make an effort to be distinct from nearby pulsars. However, the researchers' model is not intended to search for literal firefly-like optical flashes, but instead for the more abstract structures of the signal pattern: the repetition period and pulse duration.
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