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# The search for extraterrestrial life is currently built on two pillars: chemistry and radio signals
- URL: https://theparnassian.com/en/poisk-vnezemnoi-zhizni-seichas-stroitsia-na-dvukh-aspektakh-khimiia-i-radiosignaly/
- Published: 2026-07-17T12:59:56.000Z
- Updated: 2026-10-01T05:25:36.000Z
- Author: Alexandr Radayev
- Tags: Archaeology, Observations, Science

The search for extraterrestrial life is currently built on two pillars: chemistry and radio signals. Astrobiologists, astronomers and planetary scientists use spectroscopy to look in the atmospheres of distant planets for oxygen and methane, which may point to life in general, even if only bacteria. Radio astronomers listen for radio signals, that is, for evidence of an advanced technological civilisation.

Between the appearance of bacteria and the appearance of technology lie billions of years of evolution: on Earth, for instance, roughly 3.5 billion years passed. Yet if someone had tried to catch traces of technological activity on our planet with a radio telescope a few thousand years ago, nothing would have come of it, although by then the development of life on the planet had gone far beyond the kingdom of bacteria.

The gap between the search for biosignatures and technosignatures, strangely enough, may be connected with the province of ordinary terrestrial archaeologists and palaeontologists, who dig up potsherds, bones and fossils. An astrobiologist from the United States has proposed the term “noosignatures”, which could describe the as yet unidentified traces of the intermediate stages of intelligent life: everything, so to speak, between paddling in the primordial soup and sending snapshots by AirDrop.

Everyone understands that living creatures leave behind many traces of their mental activity, even without electronic technology. Tools, buildings, patterns, complex sound signals, alterations to the biosphere. The American proposes devising ways to tell a genuine trace of intelligence from mere chance.

At present the discussion concerns terrestrial archaeology, as one application of her reflections. A stone may split without any human involvement, simply from climatic or chemical action, or because another stone has fallen on it. But it may also be split deliberately, with a tool, and then worked by intelligent labour. Here one needs to introduce assembly theory, which would, for example, count how many joining operations are required to put an object together from simple parts, or what is the minimum number of iterations needed to produce a particular figure. The more such operations there are, the smaller the chance that the object came about by accident, and the greater the probability that a mind stood behind it.

Assembly theory has not merely never been applied to tools or buildings; it has not even been fully worked out. Moreover, there are plenty of “buts”, such as natural objects like crystals, which can also look intricately constructed yet exist without any biological intelligence.

Still, as an idea it is rather interesting.

Say, the stones resembling tools from Lomekwi in Kenya, 3.3 million years old and recognised as the oldest tools of all, would do very nicely as working material for testing this theory. Besides, there are dozens of still older stone finds that might lay claim to being the first industries, but which archaeologists reject as unsuitable