The PITfall of SETI

When people consider intelligent life, they often picture humanity. Most would not contend the fact that humanity is the only intelligent species on Earth. However, have we exhausted the search for traces of ancient, intelligent species? That is to say, have we considered the possibility an intelligent species existed millions of years ago, on or near Earth, with comparable intelligence? Jason Wright notes the dearth of literature on “indigenous technological species” in his recent paper. He contemplates that a search for Solar System artifacts can serve as a vector to answer the perennial question of whether life exists elsewhere.

Wright begins by providing a history of the search for extraterrestrial intelligence (SETI). Conventional SETI prioritizes interstellar radio signals, waste heat, or other methods to find life in the form of extraterrestrial intelligence. Within our local neighborhood, the search is biologically driven, focusing on the search for microorganisms on moons or biochemical markers as proxies for life. Wright makes the case to search for artifacts within our Solar System. While the exact probabilities are unknown, Wright postulates it should be easier for the origin of any artifacts or technosignatures to “be local, [rather than] an extraterrestrial species crossed interstellar space and deposited [it] here”. Given this, he coins the phrase “prior indigenous technological species” to convey an ancient species dwelling in the Solar System. Such a species possessed high intelligence but has since become either extinct or left the Solar System.

Any artifacts from this species could remain here to inform us of their past and Wright argues there are various locations to search for these artifacts, even on Earth. Many may argue the post-Cambrian fossil record should remove all doubts of another intelligent species, particularly due to the existence of endocasts. However, it is impossible to unambiguously gauge intelligence and cognitive ability from the fossil record. Wright also mentions the “Earth is quite efficient, on cosmic timescales, at destroying evidence of technology on its surface”. Geologists do believe there is a technosphere which might leave impact on the fossil record. However, artifacts on billion year timescales would probably be destroyed by tectonic processes and, at best, one could probably detect unnatural isotopic ratios. There is also the question of magmatism on an early Earth-like planet. While the oldest crust is 4.4 billion years old, the early Earth suffered from magmatism. The modern continental crust, along with plate tectonics, would have emerged much later, potentially eradicating any traces of earlier intelligent life. Wright appears to favor searching in places with little surface restructuring (unlike Venus), such as Mars, and suggests the subsurface should be searched. Other areas of interest are old objects such as asteroids or Kuiper belt objects. Exactly what type of life would persist to leave artifacts is not mentioned and this warrants consideration given the climatic changes on Earth (and Mars/Venus).

Wright’s hypothesis could read as a script for a video game like Halo. The fact that his hypothesis can reflect science fiction (or a video game) does little to bolster a search. Furthermore, this paper is easily distorted, perhaps unfairly and to Wright’s distress, to make a claim that aliens existed in the past (see here, here, or here, for less low-brow articles see here or here). This concept of an indigenous technological species is as plausible as dragons or unicorns. There is no evidence against either mythical creature, but this has not fueled a search for them. To this blogger, it is not apparent how one searches for an artifact or technosignature. We assume it is something readily disentangled from nature, but we are limited by our anthropocentric machinations. It is unsettling to form argument where (i) the answer may be beyond recognition or (ii) a conclusion is that all evidence was simply destroyed. Furthermore, it appears that a non-detection can be rendered insignificant as one could always imagine a different condition for artifact preservation. If one’s hypothesis is not testable, then it does not merit scientific consideration.