© 1984 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., “Xenopsychology,” Analog Science Fiction/Science Fact, Vol. 104, April 1984, pp 41-53

URL: http://www.rfreitas.com/Astro/Xenopsychology.htm


This paper is the first known published reference to the "Sentience Quotient" invented by Robert A. Freitas Jr., which first defined the computational density of sentient matter along a wide spectrum spanning 120 orders of magnitude, as defined by universal physical constants. The concept was first created ca. 1977-78 and was described in Freitas' privately circulated but then unpublished Xenology (1979) manuscript. (The book has since been published online.)


So far we have very little direct knowledge of alien minds --
but we have some fascinating bases for speculation.

There's a story about a psychologist," science fiction writer Murray Leinster once wrote, "who was studying the intelligence of a chimpanzee. He led the chimp into a room full of toys, went out, closed the door and put his eye to the keyhole to see what the chimp was doing. He found himself gazing into a glittering interested brown eye only inches from his own. The chimp was looking through the keyhole to see what the psychologist was doing."

What the psychologist was doing was proceeding on a false assumption; that the subject would behave as expected! Obviously even a creature that looks vaguely human may, or may not act human. How vastly more difficult must it be for us to understand extraterrestrial beings who may look I like nothing we've ever seen before? Certainly we shall be at least as surprised by alien behavior as we are by earthly minds. But evolution is even more important than physical appearance, especially where alien psychology–xenopsychology–is concerned. All living creatures, whether of this world or another, survivors in an endless chain of "winners," organisms whose behavior and sentience allowed them to succeed and increase their numbers.


Intelligence on Earth

On Earth, evolution favored voted the appearance of intelligence in two major classes of animal nervous systems, called ganglionic and chordate. It has its own peculiar psychology.

The invertebrates, representing perhaps 97% of all animal species alive today, took the ganglionic intelligence option. The earthworm is typical. Each of its many segments is almost an individual organism unto itself, having its own set of kidneys, muscles, sensors and so forth. Coordination is achieved by a thin latticework of nerve fibers crisscrossing from side to side and lengthwise. The ganglionic system resembles a ladder with bulbous neural tissues at the joints. Invertebrate organisms thus are comprised of a collection of sub-brains, each of which controls a separate part of the animal with fairly complete autonomy and no real centralized control. Sensors and their ganglia tend to cluster nearer the head, making not a true brain as we understand the term but rather a large bundle of distinct fibers. Such a nervous system is highly efficient for responding quickly to stimuli. Each clump of nerve cells becomes expert at some particular function–detecting and passing along sensory information, sweeping a leg or swing in wide uniform arc, opening and closing the jaws in slow munching motions during feeding, and so on.

Might extraterrestrials develop a high ganglionic intelligence that has, never developed on Earth despite hundreds of millions of years of opportunity? Many an evolutionary biologists believe the system is too complicated to scale up in size – invertebrates are much less intelligent than vertebrates, kilogram for kilogram. Also, ganglionic intelligence may be physically self-limiting. Typical invertebrate nervous systems just have room to accommodate mostly preprogrammed behaviors. Little space is left for growth of surplus neural matter that might eventually evolve into higher intellect. Finally, the endless cross-connections within the body can become so entangled that they actually begin to strangle other body organs. For example, massive head ganglia ringing the spider's gullet squeeze the throat so tightly that the animal must swallow its food in a thin trickle.

It is hard for us to imagine the mentality of beings with advanced ganglionic intelligence. Dr. H. Chandler Elliot, a neurologist at the University of Nebraska College of Medicine, notes that humans normally disregard their internal organs. We respond to an empty stomach or a feeling of indigestion but normally we ignore its activities. Says Elliot: "The head of an insect apparently regards not only its viscera but also its legs, wings, and so on, with similar detachment. If one deftly clips off the abdomen of a feeding wasp, the head may go on sucking, obviously not distressed. The mind of such a creature, must be alien to us almost beyond comprehension."

The second option for advanced intelligence on Earth, spinal-cord or chordate intelligence, was tried by just a few tens of thousands of species–mostly the vertebrates such as amphibians, birds. and mammals. Neural centralization is the key idea, with any number of modular sensory, analytical, or other information-processing units plugged into a coordinating "data bus." With this simple invention organisms could evolve to any size, yet continue to increase their intelligence by hooking up more "peripherals." Because of centralization spinal cords could grow far more massive than invertebrate ganglia, yet never entangle other organs of the body. The simple brain was more compact and had plenty of room to grow, perched on the tip of the notochord.

Dr. Paul MacLean, chief of the Laboratory Evolution and Behavior at the National Institute of Mental Health, believes that the evolution of the human brain involved the slow accretion of three successive neural strata. This "triune" brain, explains MacLean, "amounts to three interconnected biological computers, each with its own special intelligence, its own subjectivity, its own sense of time and space, its own memory, motor, and other functions. Thus we are obligated to look at ourselves and the world through the eyes of three quite different mentalities." These three mentalities include the reptilian brain (evolved during the Age of Reptiles) which dominates in aggressive behavior, territoriality, ritualism and the establishment of social hierarchies; the limbic brain (evolved later) which generates hormonal responses and appears to be the seat of emotion as well as short-term memory, sensitivity to pain and sexual interest; and the neocortex (developed mostly in the last 30 million years), largely responsible for deliberation initiative and caution, anticipation and planning, spatial perception, audio and visual and abstract thinking.

What if alien chordate intelligences evolve with a slightly different emphasis? One likely prerequisite for rapid neocortical development is stable internal body temperature. On another planet where warm-bloodedness had not yet been invented, the reptilian brain might predominate instead of the neocortex as in humans. Some scientists have proposed just such an intelligence among the dinosaurs, whose evolution was perhaps short-circuited by a meteorite impact 65 million years ago, causing the Great Extinction. ETs with advanced reptilian brains might display dogged aggressiveness and unyielding single-mindedness of purpose, and create societies having massive impenetrable hierarchical bureaucracies with individual actions heavily dictated by ritual gestures, elaborate ceremonies and dances, "turf" rules and highly stereotyped, emotionally cold behaviors.

A predominantly limbic intellect possibly could arise in an environment favoring the rapid development of the olfactory cortex the oldest and one of the most important components of the limbic brain in mammals. A small, hot, windy, perpetually foggy world located close to a dim red star would have little energy available for vision and any images would be wavering and distorted. Strong winds and faint air would make hearing useless, but molecules travel farther faster in a hot, thin, moving gas, thus favoring the evolution of olfaction over the other senses. A predominantly limbic-brain extraterrestrial intelligence would be heavily emotional, oriented toward pain avoidance and pleasure seeking, conciliation and altruism, and familial and sexual concerns. Their minds might be easily distractible due to a relatively short attention span.

Of course. each of MacLean's neural strata represents an earthly evolutionary experiment. Fundamentally different ones might be tried. singly or in sequence, elsewhere. An example is a bipolar mentality in which "aggressive" (fight, carnivorous, solitude, competitive, genocidal) and "nurturant" (flight, herbivorous, sociability, cooperative, parental) brains vie for control according to prevailing environmental or social conditions.

Yet another possibility is alien minds incorporating the advantages of both ganglionic and chordate architectures. For instance, each invertebrate sub-brain might evolve and enlarge to avoid multiplication of internal interconnections. This development is most likely in a radially symmetrical sea creature, wherein each brain has roughly equal access to sensory input and motor controls. Such creatures would have "collegial" mentalities, something akin to the many voting computers aboard the Space Shuttle, with multiple personalities within each organism and the ability to maintain consciousness under extreme physical trauma so long as any one brain remained functional.


Extraterrestrial Sociobiology

The father of modem sociobiology, Harvard professor Edward O. Wilson, caused quite a stir several years ago with his suggestion that human social patterns are shaped by evolutionary processes acting through our genes. He did not say that out genes drive us to a series of irresistible behavioral compulsions like ants or bees, but rather that our more malleable psychology can be influenced by our genetic makeup–human behavior can be the subject of natural selection and evolve just as our physical makeup does. Some sociobiologists believe that all behavior, as well as biology, undergoes natural selection. But where genes directly control body shape, their influence on behavior is far more subtle and plastic. Each species, say the sociobiologists, is predisposed to exhibit certain behaviors such as emotionality, aggressiveness, or sociability because these are useful survival tactics in its particular environment.

The sociobiology of competition provides one simple example. Two common forms of aggressive competition are territoriality and dominance. Territoriality is the defense of a resource-containing area by an individual or group against intruders. Dominance is the establishment of a scarce resource distribution hierarchy within a single social group based on "power" (physical strength, cunning. Wealth, etc.). Under what conditions might each behavior be favored by evolution on other worlds? Sociobiologists have learned that when important resources are distributed uniformly in space and time then is little opportunity for monopolization, and territoriality tends to occur. When important resources are highly clumped, a small proportion of the population can monopolize most of the available reward, giving rise to dominance chains or 'pecking orders.,"

Similarly, it appears that herding, flocking, and schooling are genetically preprogrammed tendencies in certain animals, mostly prey herbivores. The group avoids predation by using marginal individuals as a living shield against danger. Predators seize the first animal they encounter, so there is a great selective advantage for each individual to press toward the center of the group. "The result in evolution." explains Wilson, "would be a herd instinct that centripetally collapses populations into local aggregations."

Countless other examples of "evolved behaviors" have been examined by sociobiologists. Each behavioral predisposition appears because it allows individuals displaying it to pass more of their genes (containing, of course. the predisposition) to the next generation of offspring. In similar fashion, different alien psychologies might evolve in response to different challenges to survival elsewhere in the universe.

Wilson believes that human social behavior is best evaluated by comparison with that of other major categories of earthly species. Human beings are proud of their intelligence and many cultural achievements, but seldom pause to consider how much of their psychology can be traced back to their primate (and mammalian) ancestry. "The general traits of human nature." explains Wilson, "appear limited and idiosyncratic when placed against the backdrop of all other living species." To illustrate his point, he first refers to an inventory of the elements of human nature compiled by the American anthropologist George P. Murdock during a study of cultural universals:

Age-grading, athletic sports, bodily adornment, calendar, cleanliness training, community organizations, cooking, cooperative labor, cosmology, courtship, dancing, decorative art. divination, division of labor, dream interpretation, education, eschatology, ethics, ethnobotany, etiquette, faith healing. family feasting, firemaking, folklore, food taboos, funeral rites, games, gestures, gift giving, government, greetings, hairstyles, hospitality, housing, hygiene, incest taboos, inheritance rules, joking, kin groups, kinship nomenclature, language, law, luck superstitions, magic,. marriage, mealtimes, medicine, obstetrics, penal sanctions, personal names, population policy, postnatal care, pregnancy usages, property rights, propitiation of supernatural beings, puberty customs, religious rituals, residence rules, sexual restrictions, soul concepts, status differentiation, surgery, toolmaking, trade, visiting, weaving, and weather control.
Wilson insists that few if any of these elements are inevitable outcomes of either high intelligence or advanced social life; rather that "human nature is just one hodgepodge out of many conceivable." An entomologist by training, he has no trouble imagining an alien insectlike society whose members am even more intelligent and complexly organized than people, yet which lacks many of the qualities listed in Murdock's inventory. The alien inventory:
Age-grading, antennal rites, body licking, calendar, cannibalism, caste determinism, caste laws, colony-foundation rules, colony organization, cleanliness training, communal nurseries, cooperative labor, cosmology, courtship, division of labor, drone control, education, eschatology, ethics, etiquette, euthanasia, firemaking, food taboos, gift-giving, government, greetings, grooming rituals, hospitality, hosing, hygiene, incest taboos, language, larval care, law, medicine, metamorphosis rites, mutual regurgitation, nursing castes, nuptial flights, nutrient eggs, population policy, queen obeisance, residence rules, sex determination, solder castes, sisterhoods, status differentiation, sterile workers, surgery, symbiont care, toolmaking, trade, visiting, weather control . . . and still other activities so alien as to make mere description by our language difficult.

So intelligence and civilization are not intrinsically limited to hominoids. Only by an accident of evolution on Earth were our social characteristics linked to the anatomy of bare-skinned, bipedal mammals and the peculiar qualities of human nature. What other strange psychological "accidents" may await us on distant planets we can hardly guess.


Universal Emotions?

Emotions arc extremely important in human psychology activating our aggressiveness, sexual activity, learning and perception and a wide variety of other behaviors. Will ETs be more or less emotionally motivated than humans? Will they have emotions foreign to us, or are there any universal emotions?

First of all, what exactly do we mean by "emotion"? There is much disagreement on this, but one of the most useful definitions, by psychologist Magda Arnold, draws a careful distinction between states and behaviors. In Arnold's theory emotional experience proceeds in three steps: (1) Perception and appraisal (external stimulus is perceived and judged good, bad, useful. harmful, etc., mostly based on learned associations); (2) Emotion (internal state of arousal or "feeling" arises, involving physiological effects); then (3) Action (specific behavior such as approach, avoidance, attack, or feeding, depending on emotional intensity, learned behavioral patterns, and other motivations simultaneously present). In this view emotion is an internal state, not a behavior or a perception of external reality.

In the sociobiological view, both emotionality and behavior evolve as strategies to maximize the spread of genes. Thus the mammalian limbic brain system has been programmed to perform as if it knows that its underlying genes will be proliferated maximally only if it orchestrates behavioral responses that bring into play an efficient mixture of personal survival, reproduction and altruism.

Consider parental love. Sociobiologists believe that love is a behavioral predisposition with selective advantages for organisms which (1) are warm-blooded (love induces close physical contact permitting shared body warmth for small, high-heat-loss young), (2) produce relatively small numbers of offspring (love encourages parents to make a larger investment in time and resources per child ). (3) produce offspring that are helpless at birth (love ensures parental material support essential for infant survival), and (4) have highly plastic intelligence (love drives the parent to teach offspring very complex behaviors). Love is rare in the animal kingdom – only birds and mammals fulfill these requirements on Earth, and only these species experience the emotion. So parent love likely won't be a part of the psychology, of intelligent ETs unless they satisfy at least some of the above criteria.

Of course, extraterrestrial sentients may possess physiological states corresponding to limbic-like emotions that have no direct analog in human experience. Alien species, having evolved under a different set of environmental constraints than we, also could have a different but equally adaptive emotional repertoire. For example, assume that human observers land on another and discover an intelligent animal with an acute sense of absolute humidity and absolute air pressure. For this creature, there may exist an emotional state responding to an unfavorable change in the weather. Physiologically, the emotion could be mediated by the ET equivalent of the human limbic system; it might arise following the secretion of certain strength-enhancing and libido-arousing hormones into the alien's bloodstream in response to the perceived change in weather. Immediately our creature begins to engage in a variety of learned and socially-approved behaviors, including furious burrowing and building, smearing tree sap over its pelt, several different territorial defense ceremonies, and vigorous polygamous copulations with nearby females, apparently (to humans) for no reason at all. Would our astronauts interpret this as madness? Or love? Lust? Fear? Anger? None of these is correct, of course the alien is feeling badweather.

While xenopsychologists suspect that even emotional intelligences may not share all our feelings, they are far more certain that there exist no universal emotions among sentients. Survival and intelligence simply do not require it. Very smart aliens, is in other words, may be emotionless. Probably the cleverest nonemotional creature on Earth today is the octopus. This eight-tentacled, highly educable animal is an invertebrate mollusc with a ganglionic nervous system having 5% as many nerve cells as the human brain. The octopus has a few minor endocrine systems which influence the maturation of its sexual organs, the onset of sexual behavior, body fluids, and maternal behavior and which react to the changing length of day with the seasons – but compulsory hormonal responses appear to be absent. The animal is, from the strict mammalian viewpoint, virtually without emotion.

Octopuses are fiercely independent solitary carnivores with no social inclinations whatsoever; crowded into a small tank they will fight and establish a dominance hierarchy. They have no fear of fire and are insensitive to burns. The animal knows sex, but doesn't get very excited about it. The heartbeat of a male octopus in the midst of copulation is as steady as in a resting animal. The sexual displays of males during courtship appear to serve only for identification, never for stimulation, of the female. Broods are enormous impersonal affairs – up to 250,000 eggs per batch. No maternal love is lavished on offspring after birth so the young must fight for their own lives. Yet females often fast themselves to death guarding their own unhatched eggs.

The creature may not even know what it means to feel hungry. Mammals long deprived of food become excited and venture out in an agitated search for dinner. The response of the octopus to food deprivation is totally different and utterly alien. When crabs become scarce, octopuses resign themselves to long watchful inactivity until the day the supply improves. They become less likely to emerge from their caves and houses to attack possible prey passing by. Motivation is not as adjustable as in mammals, yet octopus behavior under stress is considerably more cool and calculating. After hundreds of hours of direct observation undersea explorer

Jacques Cousteau admitted that while the octopus is a timid animal (its first reaction to a diver is to nee or hide), "its timidity is a reasoned reaction, one that is based primarily on prudence and caution. It is not an instinctive and groundless fear (flat persists regardless of circumstances."

Octopus mentality seems to be more oriented toward calculated prudence, more plastic than reptiles and more aloof than mammals. Is this, perhaps, a clue to the possible psychology of intelligent emotionless extraterrestrials?


Alien Logic, Time, and Space

Logic is the way we know whether something is true. Denoting rationality and reason, logic lies at the very foundation (if all intellectual pursuits. Aristotle is largely responsible for the classical development of the so-called "laws of thought." 'Perhaps the best-known tenet is the Law of the Excluded Middle, which holds that if a statement is true. then its negation cannot also be true. For example, if the statement "the sky is blue" is true, then its negation "the sky is not blue" must be false. This so" of reasoning seems intuitively obvious to most people. Aristotelian logic is just common sense.

Thus not a few writers have suggested that intelligent extraterrestrials matter how physically strange they may appear, probably will think much like human beings. ETs, in other words, will be good Aristotelians. This is an unfounded and potentially dangerous assumption, even if alien sociobiology proves remarkably similar to our own. Aristotelian logic is just one of many different formal systems of logic, all of which are equally valid in mathematics and philosophy.

The danger inherent is relying on any single logic system is that it tends to limit the diversity of problems that can be addressed. One good example of this may be found in modem quantum mechanics. Imagine (the following physics experiment: A solid plate with two small parallel slits is placed in front of a beam of electrons. Behind the slits on the other side is a photographic screen to record the arrival of electrons. During the experiment, electrons are sent toward the slits one by one, some bouncing off the blocking plate and others passing through the slits to be recorded as they hit the screen. The Law of the Excluded Middle demands that any recorded electron must pass either "through the left slit" or "not through the left slit " (i.e. through the right slit). These two choices define all logical outcomes, but unfortunately nature does not cooperate. When physicists perform the experiment the "impossible" happens: The pattern recorded on the photographic screen could only have been generated if each electron passed through both slits simultaneously!

Perhaps the most exciting development for xenologicians in this century is Gödel's Incompleteness Theorem. In 1931 an American mathematician named Kurt Gödel devised a brilliant proof that any system of logic must necessarily either be internally inconsistent or incomplete. Gödel's proof demonstrated for the first time that there exist statements that are unprovable in any logic system (even the Aristotelian system) and that all arithmetic as we know it is at best incomplete, at worst inconsistent. Further, it is logically impossible to construct a single grand "metalogic" capable of subsuming all other modes of logic while remaining consistent itself. So human mathematics–the language of the physical sciences–is incomplete.

The implications in xenology are far reaching indeed. We now know, for instance, that no single system of thinking can hold, even in principle, all answers to all questions while remaining internally consistent: All logics must harbor unresolvable paradoxes. Therefore each new logic system we discover I most likely will teach us something new, some novel way of looking at the universe and understanding it in a consistent fashion which may be imperceptible–even impossible–from within previous systems of logic. To this extent all human thinking necessarily in must be incomplete. Contact with alien minds will almost certainly open new vistas of knowledge and beauty to us. Extraterrestrial logicians may find many of our most enduring paradoxes to be trivially solvable, just as we may be able to resolve some of theirs equally effortlessly.

Most living organisms possess natural cycles and rhythms, so sentient aliens should have some finite sense of duration. Dr. Bernard Aaronson, at the Bureau of Research in Neurology and Psychiatry in Princeton, New Jersey, conducted some fascinating experiments in regard to subjective time that may he highly instructive for xenopsychologists. Dr. Aaronson gave posthypnotic suggestions to human subjects to test their reactions to expanded or contracted time frames, such as: "Do you know how we divide time into the three categories of past, present, and future? When I wake you, the future will be gone. There will be no future." Subjects with no future experienced a loss of identity and a profound euphoric mystical sensation–one person reported that he "found himself in a boundless. immanent present." Expanded futures canceled all fear of death, inducing serene calmness and happiness. Elimination of the present was found to be most disturbing (subjects were inordinately depressed and behaved almost schizophrenically), whereas deprivation of the subjective past produced drowsiness, memory loss, speech difficulty, and a vague sense of meaninglessness. These kinds of experiments may someday help us understand apparently incomprehensible alien psyches.

Alien languages might incorporate concepts wholly unfamiliar to any human culture. For instance, astronomer Carl Sagan has written that if dolphins are clever enough to have language they may not have words which are arbitrary representations of concrete objects, as do humans. Rather, because of their fine sonar sense, their words may consist of sonic pictures of the object in question. Instead of an arbitrary sound for "shark," they may instead transmit a set of clicks corresponding in the audio reflection spectrum the animal would obtain upon irradiating a shark with sound waves. Another interesting proposal by psychologists David and Doris Jonas is that sentient ETs who could see polarized light (as bees can) would create a language whose vocabulary–and thinking–incorporates a running sense of time. To such eyes, objects and colors must appear different at various times of the day because of the changing angle of polarized light due to the motion of the Sun. The aliens might use a dozen words for what appears to us to he a single object.

Xenopsychologists also recognize the close association between human language and human body form. Extraterrestrials will speak, think, act, and feel differently simply because they have some other body shape and thus experience a markedly different awareness of space, position, and movement. The human body is basically bilaterally symmetric, with the upright posture universally regarded as typical. According to psychologist Donald G. MacRae, our categories for classifying, organizing, and manipulating space, and our emotions about space and the values we attach to direction in space, derive directly from our body form. Explains MacRae: "What is superior is up or high and what is inferior is down or low. Low is often dirty, but high is not necessarily clean. Right is law, morals. the holy and the strong; left is sinister, profane, weak and (often) feminine. Backward and behind are slow, hence stupid. Forward and in front are active, oriented and intelligent.  Beside is confederate or paranoid: It is an ambiguous category of place. What is clear is that these aspects of space derive from our conception of the body and would not hold for an intelligent bilateral but horizontal animal, far less for a radially symmetrical one like a clever starfish, or for spherically symmetrical beings like those of the fable in Plato's Symposium."


Sentience Quotient (SQ)

"Of all the things that have been tried by the creatures of Earth to aid survival," Cornell astronomer Frank Drake once wrote, "be it camouflage, many legs, large size as in the dinosaurs, and so forth, only one characteristic has continuously been retained and improved throughout the entire succession of species–intelligence." Perhaps the most interesting aspect of intelligence from the human point of view is that we, possibly alone among all creatures on this planet, have an awareness of self. Consciousness may be an emergent property of intelligence, a fortuitous feature of a terrestrial animal brain architecture originally designed for other jobs. Is it possible that there could exist yet higher-order emergents beyond consciousness?

Science fiction writers are fond of suggesting levels of awareness in the universe which lie totally beyond man's comprehension. In Fred Hoyle's The Black Cloud the human protagonist is killed by data overload during interaction with a vastly superior alien intellect. We may not even recognize the activities of very advanced extraterrestrial civilizations. Carl Sagan once said, "any more than an ant performing his anty labors by the side of a suburban swimming pool has a profound sense of the presence of a superior technical civilization all around him."

It is possible to devise a sliding scale of cosmic sentience universally applicable to any intelligent entity in the cosmos, based on a "figure of merit" which I call the Sentience Quotient. The essential characteristic of all intelligent systems is that they process information using a processor or "brain" made of matter-energy. Generally the more information a brain can process in a shorter length of time, the more intelligent it can be. (Information rate is measured in bits/second, where one bit is the amount of information needed to choose correctly between two equally likely answers to a simple yes/no question.) Also, the lower the brain's mass the less it will be influenced by fundamental limits such as speed of light restrictions on internal propagation, heat dissipation, and the Square-Cube Law.

The most efficient brain will have the highest information-processing rate I, and the lowest mass M, hence the highest ratio I/M. Since very large exponents are involved, for the convenience we define the Sentience Quotient or SQ as the logarithm of I/M, that is, its order of magnitude. Of course, SQ delimits maximum potential intellect–a poorly programmed or poorly designed (or very small) high-SQ brain could still be very stupid. But all else remaining equal larger-SQ entities should be higher-quality thinkers.

The lower end of our cosmic scale is easy to pin down. The very dumbest brain we can imagine would have one neuron with the mass of the universe (1052 kg) and require a time equal to the age of the universe (1018 seconds) to process just one bit, giving a minimum SQ of -70.

What is the smartest possible brain? Dr. H. Bremermann at the University of California at Berkeley claims there is a fundamental limit to intelligence imposed by the laws of quantum mechanics. The argument is simple but subtle. All information, to he acted upon, must be represented physically and be carried by matter-energy "markers." According to Heisenberg's Uncertainty Principle in quantum mechanics, the lower limit for the accuracy with which energy can be measured–the minimum measurable energy level for a marker carrying one bit–is given by Planck's constant h divided by T, the duration of the measurement. If one energy level is used to represent one bit, then the maximum bit rate of a brain is equal to the total energy available E ( = mc2) for representing information, divided by the minimum measurable energy per bit (h/T) divided by the minimum time required for readout (T). or mc2/h = 1050 bits/sec/kg. Hence the smartest possible brain has an SQ of +50.

Where do people fit in? A human neuron has an average mass of about 10-10 kg and one neuron can process 1000-3000 bits/sec. earning us an SQ rating of +13. What is most interesting here is not the obvious fact that there's a great deal of room for improvement (there is!), but rather that all "neuronal sentience" SQs, from insects to mammals, cluster within several points of the human value. From the cosmic point of view, rotifers, honeybees, and humans all have brainpower with roughly equivalent efficiencies. Note that we are still way ahead of the computers, with an Apple II at SQ +5 and even the mighty Cray I only about +9.

Another kind of sentience, which we may call "hormonal sentience," is exhibited by plants. Time-lapse photography shows the vicious struggles among vines in the tropical rain forests, and vegetative phototaxis (turning toward light) is a well-known phenomenon. All these behaviors are mediated, it is believed, by biochemical plant hormones transmitted through the vascular system. As in the animal kingdom, most of the geniuses are hunters–the carnivorous plants. The Venus flytrap, during a 1- to 20-second sensitivity interval, counts two stimuli before snapping shut on its insect prey, a processing peak of 1 bit/sec. Mass is 10-100 grams, so flytrap SQ is about +1. Plants generally take hours to respond to stimuli, though, so vegetative SQs tend to cluster around -2.

How about intelligences greater than human? Astronomer Robert Jastrow and others have speculated that silicon-based computer brains may represent the next and ultimate stage in our evolution. This is valid, but only in a very limited sense. Superconducting Josephson junction electronic gates weigh 10-12 kg and can process 1011 bits/sec, so "electronic sentiences" made of these components could have and SQ of +23 – ten orders beyond man. But even such fantastically advanced systems fall short of the maximum of +50. Somewhere in the universe may lurk beings almost incomprehensible to us, who think by manipulating atomic energy levels and are mentally as far beyond our best future computers as those computers will surpass the Venus flytrap.

Just as consciousness is an emergent of neuronal sentience, perhaps some broader mode of thinking–call it communalness–is an emergent of electronic sentience. If this is true, it might help to explain why (noncommunal) human beings have such great difficulty comprehending the intricate workings of the societies, governments, and economies they create, and require the continual and increasing assistance of computers to juggle the thousands of variables needed for successful management and planning. Perhaps future computers with communalness may develop the same intimate awareness of complex organizations as people have consciousness of their own bodies. And how many additional levels of emergent higher awareness might a creature with SQ +50 display?

The possible existence of ultrahuman SQ levels may affect our ability, and the desirability, of communicating with extraterrestrial beings. Sometimes it is rhetorically asked what we could possibly have to say to a dog or to an insect, if such could speak, that would be of interest to both parties? From our perspective of Sentience Quotients, we can see that the problem is actually far, far worse than this, more akin to asking people to discuss Shakespeare with trees or rocks. It may be that there is a minimum SQ "communication gap," an intellectual distance beyond which no two entities can meaningfully converse.

At present, human scientists are attempting to communicate outside our species to primates and cetaceans, and in a limited way to a few other vertebrates. This is inordinately difficult, and yet it represents a gap of at most a few SQ points. The farthest we can reach is our "communication" with vegetation when we plant, water, or fertilize it, but it is evident that messages transmitted across an SQ gap of 10 points or more cannot be very meaningful.

What, then, could an SQ +50 Superbeing possibly have to say to us?


Poul Anderson, Is There Life on Other Worlds? Crowell-Collier Press, New York, 1963.

Gene Bylinsky, Life in Darwin's Universe, Doubleday & Co., New York, 1981.

James L. Christian, ed., Extraterrestrial Intelligence: The First Encounter, Prometheus Books, Buffalo, New York, 1976

Richard Dawkins, The Selfish Gene, Oxford University Press, New York, 1976.

Robert A. Wallace, The Genesis Factor, William Morrow & Co., Inc., New York, 1979.

Edward O. Wilson, Sociobiology: The New Synthesis, 1975, and On Human Nature, 1978, Harvard University Press, Cambridge, Massachusetts.

Sentience Quotient References

Editor Notes:

Creation date: July 7, 1998
Last Modified: July 15, 1998
Original HTML Editor: Robert J. Bradbury

Revised and extended by Robert A. Freitas Jr., from 19 November 2002

Last updated by Freitas, 30 December 2008