ArticlePDF Available

Extraterrestrial Intelligence: A Cognitive Evolutionary Perspective



We evaluate claims for extraterrestrial intelligence based on the logic behind assertions such as the absence of evidence is not evidence of absence. To assess intelligence elsewhere in the universe we outline two of the principle scientific claims for intelligence on Earth. One involves the idea that intelligence involves working out the reasons for our own existence. The other involves self-awareness and the capacity to make inferences about what others know, want, or intend to do. The famous quote from Rene Descartes "I think; therefore, I am" needs to be revised to read "I am; therefore, I think." Some of the conclusions we derive about intelligence include the idea that most species on planet Earth have clever brains but blank minds (no self-consciousness); humans are the only species where what you know could get you killed; if humans become extinct it is highly unlikely that human-like intelligence will re-emerge on this planet and the odds of human-like intelligence evolving on other worlds is infinitely small. However, if intelligence exists elsewhere in the universe it may not have revealed itself because humans are dangerous and are perceived as posing too great a risk.
Journal of Astrobiology
Extraterrestrial Intelligence… 65
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
Extraterrestrial Intelligence: A Cognitive Evolutionary Perspective
Gordon G. Gallup, Jr*. and Hesper E. Faliveno
Department of Psychology, University at Albany, SUNY, New York
Journal of Astrobiology, Vol 12, 65-75, Published 2/16/2022
(Special Edition: Evolution of Life & Consciousness in Other Solar Systems)
We evaluate claims for extraterrestrial intelligence based on the logic behind assertions such as the
absence of evidence is not evidence of absence. To assess intelligence elsewhere in the universe we
outline two of the principle scientific claims for intelligence on Earth. One involves the idea that
intelligence involves working out the reasons for our own existence. The other involves self-awareness
and the capacity to make inferences about what others know, want, or intend to do. The famous quote
from Rene Descartes “I think; therefore, I am” needs to be revised to read “I am; therefore, I think.”
Some of the conclusions we derive about intelligence include the idea that most species on planet Earth
have clever brains but blank minds (no self-consciousness); humans are the only species where what you
know could get you killed; if humans become extinct it is highly unlikely that human-like intelligence
will re-emerge on this planet and the odds of human-like intelligence evolving on other worlds is
infinitely small. However, if intelligence exists elsewhere in the universe it may not have revealed itself
because humans are dangerous and are perceived as posing too great a risk.
Key Words: self-awareness, mental state attribution, consciousness, principle of limited imagination
1. Introduction: Extraterrestrial Intelligence?
Many scientists have attempted to make inferences about technologically advanced intelligent life
on planets in other solar systems (Falk 2022; Horvat, 2015 Joseph & Duvall, 2021; Wright & Sigurdsson,
2016). NASA has even funded a project to search for energy capturing “Dyson Sphere” megastructures,
fashioned by extraterrestrial civilizations and that may be orbiting distant stars (Oberhaus & Donlin,
2021). However, although there is controversial evidence supporting the hypothesis that prokaryotes and
simple eukaryotes which may have colonized Mars in the ancient and recent past (Armstrong, 2021a,ab;
Bianciardi et al., 2021; Elewa, 2021; Joseph et al. 2020a,b; Latif et al. 2021; Suamanarathna et al., 2021)
the only empirical proof of intelligent life, is on planet Earth. Moreover, even if “Dyson Spheres” are
discovered by NASA at some future date (Oberhaus & Donlin, 2021), given the history of life on Earth,
Journal of Astrobiology
Extraterrestrial Intelligence… 66
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
we must consider the possibility that self-aware, technologically advanced, intelligent life on other
planets, may have become extinct.
In the history of our planet, over 99% of all eukaryotic species have gone extinct (Jablonski,
2004), over 5 billion species including terrestrial mammals. As a result, life as we know it today is the
mere tip of the iceberg when it comes to the history of life on this planet.
2. Intelligence and Questioning the Why of One’s Existence
What distinguishes intelligent life from other life forms? Dawkins (1979) speculated that
intelligent life comes of age when it works out the reasons for its own existence. Falk (2022) makes
reference to brain size, cognition and intelligence, and notes that despite their large brains cetaceans lack
the ability to create tools and technology, whereas a subset of primates developed tool technology and
grammatical language and became the intellectually dominant species on this planet.
The theory of evolution is the most widely accepted scientific account of life on planet earth and,
by that yardstick, the only species that we know of, that has attempted to identify the reasons for its own
existence is Homo sapiens; and no other life form past or present comes even close to developing the
technology we have today. The stepping stones for the impetus to human technology consisted of such
things as the discovery of leverage and the invention of the wheel. Civilization can be defined by the
development of means to store acquired information in a relatively permanent form that can be
reproduced and widely disseminated over time and space. Although Gutenberg’s printing press was
created in 1450, it was not until over 400 years later (1859) that Charles Darwin published his account of
life based on the theory of natural selection.
While there are many animals that exhibit considerable sophistication and complexity in their
anatomy, physiology, and behavior, humans are unique in applying these evolved cognitive abilities to
answering questions about their origins, existence and mortality. It is often presumed that any intelligent
highly technologically advanced extraterrestrial life we encounter may have insights into these matters
that are on a par with or even exceeding our own. Yet, what if “intelligent” extraterrestrials “evolved”
from insects? Although insect societies appear complex and intelligent, there is no reason to suspect they
ask questions about the nature of existence. With the exception of humans, even complex, sophisticated
life forms do not appear capable of possessing knowledge about life and death or asking questions about
the cosmos. If intelligent life evolved on other planets there is no reason to suspect they may think like
3. Self-Awareness
Journal of Astrobiology
Extraterrestrial Intelligence… 67
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
As a testable alternative to Dawkins (1979) approach, another way to define intelligent life both
here and elsewhere is self-awareness. Some scientists contend that because there is no way to experience
anyone else’s experience, a sense of self or self-awareness falls outside the realm of science. Although no
one can experience your experience, behavioral scientists can experience and measure your behavior and
therefore they can use your behavior to infer your experience. If self-recognition is defined by the
capacity to become the object of your own attention (Gallup & Anderson. 2020), when you confront
yourself in a mirror you have literally become the object of your own attention; i.e. self-consciousness.
Unlike humans, most other visually capable species react to themselves in mirrors as if their
reflection represented another individual; and thus they engage in a variety of species typical social
responses (e.g., aggressive behavior, social gesturing, and vocalizations) directed toward their mirrored
image (Gallup & Anderson 2020). Even after prolonged experience with mirrors most species seem
incapable of realizing that their behavior is the source of the behavior being depicted in the mirror. Some
species eventually habituate to the presence of the “other” individual in the mirror and lose interest, while
others persist in showing social behavior toward the mirror (De Veer et al. 2003).
When chimpanzees initially see their reflections in mirrors they respond as if they were seeing
other chimpanzees (Gallup, 1970). But after several days they begin to use the mirror to inspect and
manipulate features of themselves that they have never seen before, such as making faces at the mirror,
inspecting their anal/genital area, and looking inside their mouths. After being anesthetized and marked
with a red dye on parts of their faces that cannot be seen without a mirror, and as evidence for self-
recognition they then use the mirror to touch and investigate these strange red marks (Gallup. 1970).
Although many claims have been made for mirror self-recognition in other animals, using this
procedure there are only three species (chimpanzees, orangutans, and humans) that have consistently
shown compelling, reproduceable, and rigorous experimental evidence of being able to decipher mirrored
evidence about themselves (Gallup & Anderson. 2020). All of the great apes, including humans, share a
now extinct protohominid ancestor in common. Orangutans were the first to diverge from this line and are
thought to be the most similar to the protohominid precursor. There is a provocative theory that the
impetus for social intelligence got its start from the fact that because of their large body mass there was
selective pressure on arboreal orangutans to develop a sense of personal agency as a means of testing the
fragility of limbs in the canopy to minimize the chances of falling (Povinelli & Cant 1995).
It should also be noted that despite frequent claims for intelligence in cetaceans and especially
bottlenose porpoises (Falk 2022), not only is the evidence for mirror self-recognition weak and the
Journal of Astrobiology
Extraterrestrial Intelligence… 68
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
methodology often questionable, but in spite of unusually large brains, their other accomplishments in the
intellectual domain are not nearly as profound as some would like to believe (Marino et al. 2007; Marino
et al. 2008). For a compelling and rigorous review of the faulty thinking, poor methodology and weak
evidence for intelligence in cetaceans see Manger (2013). It is important to remember that sophisticated,
symbolic communication among cetaceans must be a matter of fact and not faith. Unlike the latter, the
former remain in short supply.
Prior to 18 months of age most human infants respond similarly to non-human animals when
confronted with their reflection in a mirror and treat their image as if it were another child. Despite the
time and effort many parents spend in front of mirrors attempting in vain to train their children to
“recognize” themselves in the mirror, it is not until two years of age that most children show self-
Mirror self-recognition is an important cognitive indicator. For example, it has been argued that an
organism that can become the object of its own attention is in a position to begin to use its own
experience to make inferences about comparable experiences in others (Gallup, 1982). Most human
beings share the same receptors and underlying brain mechanisms in common and therefore there is
bound to be considerable overlap between your experience and those of others.
This proposition can be tested in any number of ways. If given experience with different visual
obstructions such as blindfolds or opaque goggles, most people are able to infer the inability to see in
other comparably obstructed individuals. In one such study after children of different ages were given the
opportunity to play with both clear and opaque goggles in a nursery school setting, the next day when
confronted by their mothers wearing opaque goggles, the children old enough to recognize themselves in
the mirrors acted as if their mothers could not see. Prior to reaching that age, younger children failed to
distinguish between whether their mother was wearing either clear or opaque goggles and did not realize
that while wearing opaque goggles she could not see. To apply the same logic to a hypothetical example,
imagine that you were to teach a captive baboon to vocalize in order to receive a food reward such as a
raisin. Once the baboon learns over a series of days to vocalize when you enter the room for raisins, you
give the baboon experience with different auditory obstructions such as headphones. Then the next day
you enter the room wearing the familiar pair of headphones to see if the baboon will raise the volume of
its initial vocalizations in an attempt to compensate for your inability to hear. This is a testable/falsifiable
hypothesis and given that baboons consistently fail tests of mirror self-recognition (Anderson & Gallup.
1999) they would be expected to fail to use their experience with headphones to infer your obstructed
Journal of Astrobiology
Extraterrestrial Intelligence… 69
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
ability to hear.
The expansion and refinement of self-awareness paves the way for the development of social
intelligence (Gallup, 1982). Not only can we use our experience to infer comparable experiences in others
but, given a knowledge of our own mental states and their relation to external events, we now have a
means of inferring mental states in others. In other words, knowledge of self builds the foundation for an
introspectively derived knowledge of others. As a result, social intelligence is expressed by the
emergence of increasingly more sophisticated social strategies for inferring and effectively responding to
emotions and mental states in others such as gratitude, grudging, sympathy, empathy, deception, and
sorrow. Based on this ability to infer what other people know, want, or intend to do, human competition
for scarce resources and mating opportunities has come to be waged, not only in terms of physical
prowess, but increasingly in terms of more cognitively sophisticated social interactions. Indeed, with the
industrial revolution intellectual prowess in humans has in many instances come to supplant physical
prowess as a means of achieving upward mobility in socioeconomic dominance hierarchies.
It is important to acknowledge that self-awareness and social intelligence, rather than being an
alternative to Dawkins’ definition of intelligence actually subsume it. One first has to be aware of their
own existence before they can begin to work out the reasons for that existence. From this perspective, the
famous quote from Rene Descartes, “I think; therefore, I am” would have to be rewritten to read, “I am;
therefore, I think.” It is your ability to conceive of yourself in the first place and ponder your own
existence that makes mental state attribution and thinking possible.
4. Extraterrestrial Life
Should we ever encounter complex life elsewhere in the universe--species more advanced that
bacteria, algae, lichens, and fungi-- a parsimonious and straightforward measure of whether it might be
intelligent would be to assess its capacity to recognize and decipher mirrored information about itself.
The history of biology on earth makes it clear that intelligent, technologically sophisticated life is
the exception rather than the rule. Despite billions of different lifeforms, the track record of intelligent
life with complex tool-making capabilities and the cognitive ability to achieve self-consciousness,
indicate that it has only appeared once, which makes the prospect of finding technologically sophisticated
intelligent life elsewhere exponentially remote.
Consider again, the planet Mars. Although prokaryotes and perhaps algae may have colonized the
Red Planet over 3 billion years ago, and despite controversial evidence that tube worms and simple
legless metazoans may have evolved (Armstrong, 2021a,ab; Bianciardi et al., 2021; Elewa, 2021; Joseph
Journal of Astrobiology
Extraterrestrial Intelligence… 70
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
et al. 2020a,b; Latiff et al. 2021; Suamanarathna et al., 2021) no serious scientist has made the claim that
this progression led to the evolution of intelligent Martians. Likewise, although light-blocking mega-
structures appear to be orbiting ancient stars, suggestions about energy capturing “Dyson Spheres” are
purely speculative (Horvat, 2015 Joseph & Duvall, 2021; Wright & Sigurdsson, 2016) and may be due to
massive groupings of orbiting comets or moon-size debris.
Due to the number evolutionary transitions necessary for tool-making, grammatically speaking,
intelligent life to emerge, the chances of anything resembling human intelligence to have evolved
elsewhere would be “vanishingly small” (Gould, 1990). Another way to emphasize this point is with
statistics. Statistical inferences require taking into account the sample size (N) to determine the degrees of
freedom by the formula N-1. With a sample based on a single instance, the degrees of freedom drop to
zero. Which means that based on inductive logic there is no statistically responsible basis for inferring
that technologically advanced intelligent life exists elsewhere; a principle consistent with the Law of
Parsimony or Occam’s Razor. An alternative interpretation is that the law of parsimony actually amounts
to the principle of what we call limited imagination. God, metaphorically speaking, does not always
shave with Occam’s Razor.
Some might argue that the absence of evidence is not evidence of absence, and therefore the
presence of human-like intelligent life elsewhere remains viable. Hence, NASA’s program designed to
detect energy capturing megastructures orbiting distant stars (Oberhaus & Donlin, 2021). Yes, something
is blocking the light from a few stars in other solar systems. Yes, anomalous objects have been observed
and filmed moving at tremendous speeds by U.S. Navy pilots. However, a few hundred years ago,
similar observations--including comets passing overhead or eclipses of the sun or moon-- have been
claimed as evidence of angels or the wrath of god. Science is a matter of fact, not faith, and it is important
to realize that in some instances the absence of evidence can indeed be evidence of absence. In order to
be a scientific question, it has to be an empirical question, a question that can be answered based on
convincing evidence that can be scientifically replicated and validated; i.e. a testable hypotheses that can
be verified or falsified.
Replication is one of the cornerstones of science. This also applies with equal force to the null
hypothesis or the absence of an effect. If the absence of an effect can be replicated enough times under
different conditions, then eventually we have to begin to take the null hypothesis seriously. For instance,
there is no evidence for mirror self-recognition in children prior to one year of age. By the same token,
although the search for extraterrestrial life and the technology available to do so is only in its infancy, the
Journal of Astrobiology
Extraterrestrial Intelligence… 71
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
accumulation of failed attempts with each passing day builds the case in favor of the absence of evidence.
Any discussion of extraterrestrial intelligence whether it is pro or con should acknowledge Carl
Sagan as an outspoken proponent (Sagan, 1995). Since the Drake equation laid out a probabilistic
argument for intelligent life beyond Earth (Drake, 1962), there have been numerous attempts to estimate
the number of extraterrestrial life forms present in the Milky Way galaxy (Vakoch & Dowd, 2015) and
there is wide disagreement about estimates for extraterrestrial intelligence (Golden 2021). A similarly
large number of opinions exist when estimating the number of potentially life-bearing planets (Sandberg.
2018; Scarf & Cronin, 2016).
Despite continuous assessments prompting researchers to propose high estimates of extraterrestrial
intelligent species (see Cai et al. 2021), and despite evidence of megalithic light-blocking structures
orbiting a few stars in other solar systems (Horvat, 2015 Joseph & Duvall, 2021; Wright & Sigurdsson,
2016) there remains no proof to support any claims these were constructed by advanced alien
civilizations (i.e., the Fermi paradox). Moreover, even with extensive and coordinated international
efforts to scan space via Breakthrough Listen (see Price. 2021), no meaningful techno signatures have
been detected beyond our solar system. Hence, recent arguments for the discovery of an extraterrestrial
artifacts (Loeb, 2021; Oumuamua, 2021) are highly controversial and flawed (Cowie, 2021).
5. Extinction Events & Intelligent Life
If humans were to become extinct there is no compelling reason to expect that a similar form of
intelligent life might re-emerge on this planet.! Evolution does not occur by design; it occurs by natural
selection, improving the probability of reproductive success. Each species has emerged via complex
interactions involving genetic and fluctuating environmental conditions that add to stochastic changes in
allele frequencies over time.! These complex interactions make it unlikely that the same species might
again evolve at some future date on this planet. The odds of similar interactions leading to the evolution
of humans on another world may be infinitely remote.
Perhaps a more prudent explanation for the lack of any compelling evidence for extraterrestrial
intelligence is that intelligent life commensurate with the intellectual abilities of humans is exceptionally
rare (Carter, 1983; Mayer, 1995). Consistent with this view, recent analyses which incorporate the series
of improbable steps required for the emergence of intelligence on Earth suggests that the amount of time
for the evolutionary transitions required for intelligence to evolve (1 to 2 billion years) may exceed the
habitable windows of many exoplanets (Synder-Beattie et al. 2021). Mars and Venus, for example, orbit
within the habitable zone of our solar system; yet there is no evidence of intelligent life. Even if Mars and
Journal of Astrobiology
Extraterrestrial Intelligence… 72
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
Venus may have been habitable billions of years ago, and despite evidence supporting the possibility that
algae, fungi, and lichens may have colonized the Red Planet (Armstrong, 2021a,ab; Bianciardi et al.,
2021; Elewa, 2021; Joseph et al. 2020a,b; Latif et al. 2021), there is again no evidence of intelligent life.
Even if intelligent life evolved on other planets, they may have become extinct. Consider, again,
that over 99% of complex eukaryotic life has become extinct. Estimates are that there have been five
major extinctions, and with species continually evolving and becoming extinct. Again, consider the
controversial evidence from Mars. Even if we grant that algae, fungi, lichens and simple metazoans
evolved, there is no evidence of any progression leading to intelligence or “Martian” self-awareness.
Earth may be the exception, and Mars may be typical of habitable planets throughout this and other
galaxies, where life remains no more intelligent or complex than a mushroom.
Many believe that evolution lacks a conscious, intentional, deliberate component. Yet the process
of evolution has paradoxically given rise to humans that are capable of conscious, intentional, deliberate
acts – even those leading to the demise of other species and putting the existence of our own species at
risk. Humans are not only unique in their capacity to apply a scientific approach to the reasons for their
own existence, they are unique in their capacity to speculate about intelligent life here and elsewhere in
the universe. They are also unique in that they have developed the technological capability to cause their
own extinction.
Humans appear to be poised at the brink of reaching the tipping point when it comes to our
dependence on fossil fuels and the resulting effects on climate change. The trajectory suggests that for the
first time in the history of Earth, we are headed for a mass extinction that is occurring as a result of the
actions of a single species; i.e., humans (Sampson & Roopnarine, 2001).
Will human cause their own extinction? If intelligent life, similar to humans evolved on other
worlds, may they have caused their own extinction? Is this why there is no compelling evidence to
support the hypothesis that intelligent life evolved on other worlds? Intelligence is not always adaptive
and there is no propensity for intelligence to emerge or evolve in the first place; if it were, intelligent
creatures would be the norm and not the exception.
6. Maybe Intelligent Extraterrestrial Life Does Not Want to be Found
Over a decade ago the famous astrophysicist, Professor Stephen Hawking raised and popularized
concerns about the dangers posed by intelligent and hostile extraterrestrials who might arrive to conquer,
enslave, destroy, and colonize humans to exploit the resources of our planet having exhausted those of
their own. According to Hawking the outcome might be analogous to when Columbus came to America
Journal of Astrobiology
Extraterrestrial Intelligence… 73
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
which did not turn out well for Native Americans.
Another way to think about intelligent life elsewhere is that if it exists it may have found us by
now and discovered that humans are dangerous, violent and ceaselessly engage in endless bloody
conflicts and war, and continually develop even more powerful weapons of mass destruction. It would
also be obvious, that as a byproduct of increasing pollution, habitat destruction, coupled with endless
wars, pillage, death, destruction and the desire for conquest, that humans pose an unparalleled and
unprecedented risk not only to other life forms on Earth but to life on other planets.
Consider the total destruction of the highly advanced Aztec and Inca civilizations, the subsequent
enslavement and genocide of the native peoples, their temples and buildings destroyed, their wealth and
natural resources stolen and shipped across the seas. If the humans of Earth became aware of advanced
civilizations and desirable resources on other worlds, might these native extraterrestrial populations
eventually suffer the same fate as befell the natives of Mexico and Peru?
If there is intelligent life elsewhere, they may view humans as extremely dangerous. Maybe this is
why there is no proof or compelling evidence of extraterrestrial intelligence: we pose too great a risk, and
they do not want to be discovered.
Acknowledgements: We thank the editors and referees at the Journal of Astrobiology, and Andrew C.
Gallup and Michael J. Frederick for helpful comments on earlier versions of this paper.
Anderson J R, Gallup G G, Jr. Self- recognition in nonhuman primates: Past and future challenges. In
Animal Models of Human Emotion and Cognition, edited by M Haug and RE Whalen, American
Psychological Association, 1999, pp 175-194.
Armstrong, R. A. (2021a). Statistical Analysis of ‘Tube-Like’Structures on Mars Photographed by
Curiosity and Opportunity and Comparisons with Terrestrial Analogues. Journal of Astrobiology, 10,
Armstrong, R. (2021b). Martian Spheroids: Statistical Comparisons with Terrestrial Hematite (‘Moqui
Balls’) and Podetia of the Lichen Dibaeis Baeomyces. Journal of Astrobiology, 7, 15-23.
Bianciardi, G., Nicolò, T., & Bianciardi, L. (2021). Evidence of Martian Microalgae at the Pahrump Hills
Field Site. A Morphometric Analysis. Journal of Astrobiology, 7, 70-79.
Cai X, Jiang J H, Fahy K A., Yung Y L. A Statistical Estimation of the Occurrence of Extraterrestrial
Intelligence in the Milky Way Galaxy. Galaxies 2021;9: 5.
Carter B. The anthropic principle and its implications for biological evolution. Philosophical Transactions
of the Royal Society of London. Series A, Mathematical and Physical Sciences 1983: 310: 347-363.
Cowie C. The ‘Oumuamua controversy. Nature Astronomy 2021; 5: 526-527. Dawkins R. The Selfish
Gene. Oxford University Press, 1979.
de Veer M W, Gallup G G, Jr., Theall L A, van den Bos, R, Povinelli D J (2003). An eight-year
Journal of Astrobiology
Extraterrestrial Intelligence… 74
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
longitudinal study of mirror self-recognition in chimpanzees (Pan troglodytes). Neuropsychologica
2003; 41: 229- 234.
Drake F. (1965). The radio search for intelligent extraterrestrial life. Current Aspects of Exobiology 1965;
32: 323.
Elewa, A. M. (2021). Fossils on Mars: A Brief Review of the Evidence. Journal of Astrobiology, 7, 29-37.
Falk, D. (2022). Implications of Brain Evolution in Cetaceans and Primates for Highly Intelligent
Extraterrestrial Life, Journal of Astrobiology, 12, 45-64.
Gallup G G, Jr. (1970). Chimpanzees: Self-recognition. Science 1970; 167: 86-87.
Gallup G G, Jr. (1998). Self-awareness and the evolution of social intelligence. Behavioural Processes
1998; 42: 239-247.
Gallup G G, Jr. Anderson J R (2020). Self-Awareness in Animals: Where Do We Stand 50 Years Later?
Lessons from Cleaner Wrasse and Other Species. Psychology of Consciousness: Theory, Research,
and Practice, 2020; 7: 46-58.
Golden L M. (2021). A joint mind consideration of the Drake equation in the search for extraterrestrial
intelligence. Acta Astronautica, 2021;185: 333-336.
Gould, SJ. (1990). Wonderful Life: The Burgess Shale and the Nature of History. Norton, New York.
Horvat, M. (2015). KIC 8462852: Remnants of a Failed Early Type II Civilization? Cosmology, 20.
Jablonski, D. (2004). "Extinction: past and present". Nature 2004; 427: 589.
Joseph, R., & Duvall, D. (2021). Fungi on Mars and Extraterrestrial Civilizations. Genetics, Evolution,
Alien Megastructures and Ancient Stars. Journal of Cosmology 30, 103-156.
Joseph, R., Planchon, O., Duxbury, N.S., Latif, K., Kidron, G.J., Consorti, L., Armstrong, R. A., ! Gibson,
C. H., Schild, R., (2020a). Oceans, Lakes and Stromatolites on Mars, Advances in Astronomy, 2020,
Joseph, R.G., Duxbury, N.S. Kidron, G.J. Gibson, C.H., Schild, R. (2020b) Mars: Life, Subglacial
Oceans, Abiogenic Photosynthesis, Seasonal Increases and Replenishment of Atmospheric Oxygen,
Open Astronomy, 2020, 29, 1, 189-209.
Joseph, R., et al. (2021a) Tube Worms, Hydrothermal Vents, Life On Mars? A Comparative
Morphological Analysis, Journal of Astrobiology, 8.
Joseph, R., Armstrong R.A., Wei, X., Gibson, C., Planchon, O., Duvall, D., Elewa, A.M.T., Duxbury, N.,
Rabb, H., Latif, K., Schild, R. (2021b). Fungi on Mars? Evidence of Growth and Behavior From
Sequential Images. Astrobiology Research Report, 5/1/2021, https:// Journal of Cosmology, 30: 440-475.!
Latif, K., Ray, J. G., & Planchon, O. (2021). Algae on Mars: A Summary of the Evidence. Journal of
Astrobiology, 7, 22-28.
Loeb A. (2021). Extraterrestrial: The First Sign of Intelligent Life Beyond Earth. Houghton Mifflin, 2021.
Mayr E. (1995). Can SETI succeed? Not likely. Bioastron News 7, 1995.
Manger P R. (2013) Questioning the interpretations of behavioral observations of cetaceans: Is there
really support for a special intellectual status for this mammalian order? Neuroscience 250 2013;
Marino L, Connor RC, Fordyce RF et al. (2007). Cetaceans have complex brains for complex behavior.
PLoS Biology 2007; 5: 966-972.
Marino L, Butti C, Connor RC et al. (2008). A claim in search of evidence: reply to Manger’s
thermogenesis hypothesis of cetacean brain structure. Biological Review 2008; 83: 417-440.
Oberhaus, D. & Donlin, K. (2021). NASA is supporting the search for alien megastructures. https://
Povinelli DJ, Cant JG. (1995) Arboreal clambering and the evolution of self-conception. Quarterly
Journal of Astrobiology
Extraterrestrial Intelligence… 75
Journal of Astrobiology, 12, 65-75, 2022 Copyright © 2022
Review of Biology 1995; 4: 393-421.
Price D. (2021). Breakthrough Listen is scanning more of space than ever to try to find intelligent life.
IEEE Spectrum 2021; 58: 34-39.
Sagan, C. (1995). The Abundance of Life Bearing Planets. Bioastron News. 7:1-4
Sampson S, Roopnarine P. SETI Talks: Is a Sixth Mass Extinction the future of living species on Earth?
2021. Available online at
Sandberg A, Drexle, E, Ord T. (2018). Dissolving the Fermi paradox. arXiv preprint arXiv
Scharf C, Cronin L. (2016). Quantifying the origins of life on a planetary scale. Proceedings of the
National Academy of Sciences 2016; 113: 8127-8132.
Snyder-Beattie A E, Sandberg A, Drexler K E, Bonsall M B. The timing of evolutionary transitions
suggests intelligent life is rare. Astrobiology 2021; 21:265-278.
Suamanarathna, A. R., Aouititen, M., & Lagnaoui, A. (2021). Tube Worm-Like Structures, Hematite, and
Hydrothermal Vents on Mars: Support for, and Opposition to Joseph et al. Journal of Astrobiology,
10, 38-62.
Vakoch D A, Dowd M., eds. (2015) The Drake equation: estimating the prevalence of extraterrestrial life
through the ages Vol. 8. Cambridge University Press 2015.
Wright, J. T., & Sigurdsson, S. (2016). Families of Plausible Solutions to the Puzzle of Boyajian’s Star.
The Astrophysical Journal Letters, 829(1), L3.
Full-text available
There are planets in this galaxy over 10 billion years in age. Given the necessity of a stabilizing moon to prevent chaotic obliquity, the number of habitable planets upon which human-like intelligent life could have evolved may range from a minimum of 155 worlds to over 8 billion planets in this galaxy. Intelligent life that evolved on these older worlds may have reached what Nikolai Kardashev has described as Type I, II, III extraterrestrial civilizations billions of years ago. Type I civilizations may be capable of visiting and exploiting other planets in their solar system. Humans of Earth may not reach Type I status for another 200 years. Type II extraterrestrial civilizations would have developed the capacity to exploit the energy resources of their own stars and could have engineered energy capturing megastructures (Dyson spheres). Type III may be capable of harnessing the energy of entire galaxies. It is proposed that Type IV would be capable of conquering the universe and creating a universe and other dimensions. Robotic Artificially Intelligent civilizations may have also evolved in the transition from Type I to Type II. Type II and Type III extraterrestrial civilizations may account for what is now described as "Unidentified Aerial Phenomena." If Earth is under extraterrestrial surveillance they may be relying on the non-habituation anthropological observational model so they do not affect "natural" human behavior and (A) intend us no harm; or (B) they are monitoring our technological development and if humans become a threat they may destroy our technology and civilization; or (C) as warned by Stephen Hawking, they intend to conquer our planet.
Full-text available
There are stars and Earth-like planets believed to be over 10 billion years in age. "Water worlds" and moons that contain salty oceans may be commonplace in this galaxy. The evolution of cetaceans and primates may provide some clues as to how intelligent life may have evolved on other planets. The most intelligent species of primate, Homo sapiens, has an average brain mass (~1350 g) that is considerably larger than any of the other primates but much smaller than the averages for many cetaceans, which are also believed to be very intelligent. The factors that led a subset of primates rather than the comparatively huge-brained cetaceans to dominate (from a human perspective) our planet are reviewed, including language and tool making capability. If intelligent cetacean-like beings evolved convergently in other worlds in response to aquatic habitats similar to Earth's, they would not be expected to have complex tools and technologies, whereas primate-like beings that may have evolved convergently on other planets that are much older than Earth might have long ago developed technologies that surpass our own.
Full-text available
Statistical comparisons were made between various ‘tube-like’ structures photographed on Mars by Curiosity and Opportunity rovers in Gale and Endurance craters respectively and the worm ‘cases’ of terrestrial tube worms. Various statistical analyses, including principal components analysis (PCA) based on various metrics, suggested considerable similarities between the Martian tube-like structures and their terrestrial counterparts. Although, statistical comparisons cannot ‘prove’ that these tube-like structures on Mars represent tube worms, they provide a more objective basis for morphological comparison, thus supporting the conclusions of Joseph et al. (2021a). Given the significance and implications of such data, further observations are urgently needed to increase sample sizes available for statistical study.
Full-text available
The observation of tubular structures within Endurance Crater, Mars, has been reported by Joseph et al (2021a,b) who hypothesized these may be mineralized and fossilized remnants of tube worms that in the ancient and recent past flourished within lakes of water heated by thermal vents. The discovery of what may be spherical hematite in this same vicinity supports the hydrothermal vent scenario, whereas the claims by Joseph (2021; Joseph et al. 2021c) that these spherules are fungal puffballs does not. This evidence from Endurance Crater and associated mineralogy and chemistry is reviewed. We conclude that the ancient lakes of Endurance Crater may have been heated by thermal vents and inhabited by tubular organisms that became mineralized, as hypothesized by Joseph et al; and that these same hydrothermal vents formed hematite spherules as hypothesized by the rover Opportunity team.
Full-text available
Statistical comparisons were made between the populations of Martian spheroids photographed by Opportunity and terrestrial Moqui balls and between the stalked Martian spheroids and reproductive podetia of the lichen Dibaeis baeomyces. Principal components analysis (PCA)based on various metrics suggested significant differences in statistical properties of the Martian spheroids compared with the Moqui balls but considerable similarities between the stalked spheroids and the lichen podetia. These preliminary results suggest that Moqui balls are not a good terrestrial analogue of the Martian spheroids and support the hypothesis that the stalked spheroids may represent the reproductive podetia of a lichen; albeit considerably strengthened via mineral deposition to survive the Martian environment.
Full-text available
Hundreds of tubular and spiral specimens resembling terrestrial tube worms and worm tubes were photographed in the soil and atop and protruding from “rocks” on Sols 177, 199 and 299 in the vicinity of Endurance Crater, Meridiani Planum. Dozens of these putative “worms” and tubes are up to 3 mm in size. These tubular specimens display twisting, bending, and curving typical of biology and are different from abiogenic structures. Morphological comparisons with living and fossilized tube worms and worm tubes also supports the hypothesis that the Martian tubular structures may be biological as they are similar and often nearly identical to their terrestrial counterparts. The literature concerning abiotic and biotic formation of mineralized tubular formations is reviewed and the Martian tubular structures meet the criteria for biology. In addition, larger “anomalous” oval-specimens ranging from 3 mm to 5 mm in diameter were photographed and observed to have web-like appendages reminiscent of crustacean pleopods. That marine organisms may have evolved and flourished in the vicinity of Endurance Crater, Meridiani Planum, was originally predicted by NASA’s rover Opportunity crew in 2004, 2005, and 2006. This area is believed to have hosted a briny body of water that was heated by hydrothermal vents; and these are favored habitats of tube worms. Further, all these specimens were photographed adjacent to vents in the surface and the mineralogy of Endurance Crater is similar to that produced by tube worms and their symbiotes. However, if any of these specimens are alive, fossilized, mineralized or dormant is unknown. Abiotic explanations cannot be ruled out and it cannot be stated with absolute certainty they are biological.
Full-text available
Reviewed in this report: It took a minimum of 7 billion years of genetic duplicative events for the first gene to become a life sustaining genome; i.e. at least 2.4 billion years before Earth was formed. Potentially habitable planets have been identified at least 5 billion years older than Earth. Microfossils have been found in meteors older than this solar system including evidence of evolutionary progression leading to corals and sponges. There is evidence of life, fossils and evolution on Mars paralleling Earth leading up to the Cambrian Explosion. The implications are: life on Earth-like planets evolves in patterns similar to life on Earth. Megastructures have been observed orbiting our own and distant suns. For thousands of years there have been reports of flying craft (“Unusual Aerial Phenomena”). According to a report by the U.S.A Office of the Director of National Intelligence these “Unidentified Aerial Phenomena” engage in maneuvers at hypersonic speeds that are completely beyond our technological capabilities or understanding. The implications are that Earth and its inhabitants are under surveillance. It is concluded that intelligent life and technologically advanced extraterrestrial civilizations have evolved in this galaxy on numerous Earth-like worlds, including those billions of years older than our own.
Full-text available
The discovery and statistical analysis of fossils on Mars is reviewed. Fossilized formations similar to tube worms, and Ediacarans and Metazoans have been reported. The possibility these organisms evolved from algae that constructed stromatolites early in the history of Mars is discussed in the context of extinction using Earth as an analog.
Full-text available
Numerous estimates exist of the factors appearing in the Drake equation, which estimates the number of extant communicative civilizations in the Milky Way galaxy. Although each are presented by scholars in the field, wide disagreement of the values of those factors exist. Here we consider the six non-longevity factors as random variables and utilize estimates from six studies to determine probability density functions for those factors. We then utilize them to perform a Monte Carlo analysis to determine the most likely value for the product. We find, in moderately close agreement with the estimate by both Frank Drake and the Cyclops report, a value for the product of 0.85 ± 1.28 years⁻¹.
Full-text available
In the field of astrobiology, the precise location, prevalence, and age of potential extraterrestrial intelligence (ETI) have not been explicitly explored. Here, we address these inquiries using an empirical galactic simulation model to analyze the spatial–temporal variations and the prevalence of potential ETI within the Galaxy. This model estimates the occurrence of ETI, providing guidance on where to look for intelligent life in the Search for ETI (SETI) with a set of criteria, including well-established astrophysical properties of the Milky Way. Further, typically overlooked factors such as the process of abiogenesis, different evolutionary timescales, and potential self-annihilation are incorporated to explore the growth propensity of ETI. We examine three major parameters: (1) the likelihood rate of abiogenesis (λ_A); (2) evolutionary timescales (T_(evo)); and (3) probability of self-annihilation of complex life (P_(ann)). We found P_(ann) to be the most influential parameter determining the quantity and age of galactic intelligent life. Our model simulation also identified a peak location for ETI at an annular region approximately 4 kpc from the galactic center around 8 billion years (Gyrs), with complex life decreasing temporally and spatially from the peak point, asserting a high likelihood of intelligent life in the galactic inner disk. The simulated age distributions also suggest that most of the intelligent life in our galaxy are young, thus making observation or detection difficult.
Evidence from Mars of what may be algae, thrombolites, microbialites, microbial mats, stromatolites, and ooids is summarized. Also briefly discussed is evidence of chlorophyll, seasonal fluctuations in atmospheric oxygen, and what may be photosynthesis-oxygen gas vents adjacent to specimens resembling algae and lichens. The possible presence of calcium carbonate and calcium oxalate is also summarized the latter of which might be produced by lichens: an algae-fungi symbiotic organism that Joseph et al. (2021) believe are attached to rocks on Mars.