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The Specifications of Extraterrestrial Intelligence

by John G. Cramer

Alternate View Column AV-177
Keywords: extraterrestrial, intelligence, sociobiology, natural, selection, individual, group
Published in the May-2015 issue of Analog Science Fiction & Fact Magazine;
This column was written and submitted 11/07/2014 and is copyrighted 2014 by John G. Cramer.
All rights reserved. No part may be reproduced in any form without
the explicit permission of the author.

    The eminent Harvard biologist and philosopher of science, Edward O. Wilson, noted for his creation of the field of sociobiology and for his many books, has written a new book, The Meaning of Human Existence. It should be of great interest to the readers and writers of science fiction. The book attempts to explain how humanity has come to its present state of existence because of the forces of natural selection as they act on individuals and on groups. In particular, based on the lessons learned from the record of evolution that lead from viruses and bacteria to vertebrates to human beings, Wilson has attempted to produce a list of specifications of how some hypothetical intelligent beings that might have evolved on an earth-like planet of another star system would look and act.

    SF writers usually base their intelligent aliens on the assumption that the processes of evolution on an alien planet have produced some intelligent life form that in the course of time, because of its intelligence, proceeds to develop a complex technological civilization. Some of my favorite SF writers have invented fascinating alien species that combine instinctual animal behavior with high intelligence. Examples are Larry Niven's tiger-like carnivorous Kzin, his sheep-like herbivorous Puppeteers, and Poul Anderson's eagle-like territorial Ythrians. All became intelligent enough to form highly developed technological civilizations, carrying their innate animal behaviors with them to the stars.

    However, Wilson would say that the SF writers have it backwards: the random walk of evolutionary development and varying conditions of environment generates a species that by chance develops a cooperative social structure. Then, if the conditions are just right, the existence of that cooperative social structure pushes the development of intelligence. He traces the development of intelligence from the primarily vegetarian Australopithecines (which had a 600 cc brain volume) to meat-eating Homo Habilis (680 cc brain volume) to Homo Erectus (900 cc brain volume) to Homo Sapiens (1,400 cc brain volume). Wilson suggests that the initial innovation in Homo Habilis of including meat in their diet led to the establishment of semi-permanent camps in which the young were protected and to which roving cooperative hunters brought meat to feed the group. This led to villages with complex cooperative social structures. These ultimately led to cities, civilization, and technology. At each step along this path, increased intelligence provided group and individual advantages, and so high intelligence emerged.

    Wilson points out that such cooperative social structures are very rare among the animal species. The 400 million years of evolution on Earth has produced only 20 examples of species, with complex social structures, and most of these are insects. All of these social species developed rather late in the game, and all have been very successful. For example, among all of the highly variable insect species, only two groups of socialized insects, ants and termites, comprise about half of the total global insect biomass by weight, which can be taken as a measure of their success.

    In Chapter 10 of his book, Wilson uses the lessons learned in analyzing the intellectual and social development of Homo Sapiens to predict the characteristics of a hypothetical intelligent alien species that might develop on an earth-like planet of another star system. In what follows I have condensed and paraphrased Wilson's logic, but the arguments are basically his. We will consider his predictions one at a time:

(1) Intelligent Aliens will be land-dwellers, not aquatic. The final ascent to human intelligence required the use of fire as a portable high-energy source in developing technology beyond the stone-age level. It is difficult to imagine an ocean-dwelling species reaching iron-age technology.

(2) Intelligent Aliens will be relatively large animals. The most intelligent land animals, in descending order, are Old World apes and monkeys, elephants, pigs, and dogs, all at the high end of the animal size spectrum. Small body size means smaller brains, on the average, less memory capacity, and lower intelligence. The hypothetical aliens would probably have a body mass around 10 to 100 kg, i.e., somewhere between a dog and a human.

(3) Intelligent Aliens will be biologically audio-visual. In terms of sensory perception, humans, with their reliance on sound and sight in very restricted frequency bands, represent a rather isolated group. Most of the animal world depends much more directly on smell and on the use of specialized body-generated pheremone chemicals for signaling and communication. However, pheremones are unsuitable for rapid communication, and therefore represent a road block on the path to high intelligence. The hypothetical aliens could use facial expressions or sign language for communication. However, "telepathy" is ruled out, unless a species developed the capability of internally generating and detecting radio waves or electrical signals as communication. While electric eels and catfish have some capabilities in this direction, it has developed because they are adapted to murky environments in which vision is not useful.

(4) Intelligent Aliens will have a large distinct head located up front. All land animals have elongated, bilaterally symmetric bodies, with brains and key sensory inputs located in a head adapted for quick scanning and action. The hypothetical aliens should be similar.

(5) Intelligent Aliens will have light to moderate jaws and teeth. Animals with heavy mandibles and massive grinding teeth are typically vegetarians that eat coarse low-energy vegetation. Animals with fangs and horns use them for defense against predators and for competition among males. The hypothetical aliens should have progressed by cooperation and strategy rather than brute strength and combat. Only a broad high-energy meat and vegetable diet could sustain the relatively large populations needed for the later stages in the development of intelligence. Hence, moderate jaws with no fangs or horns.

(6) Intelligent Aliens will have a very high social intelligence. All social insects (wasps, bees, termites, ants) and the most intelligent mammals live in groups whose members simultaneously compete and cooperate. Functioning in such a fast-moving and complex social network requires a great deal of social intelligence.

(7) Intelligent Aliens will have a small number of free locomotory appendages, levered for maximum strength with stiff internal or external skeletons composed of hinged segments (as by human elbows and knees), and with at least one pair that are terminated by digits with pulpy tips used for sensitive touch and grasping. The four-legged-ness of land vertebrates is perhaps because fishes with four lobe-fins (instead of six) colonized the land. Insects have six locomotory appendages, and spiders have eight. Evidently a relatively small number of such appendages is good for evolutionary success on land. Only chimps and human invent tool artifacts, presumably because of the utility of fingers with soft sensitive tips. A technological civilization that depended on beaks, talons, scrapers, or claws for tool manipulation is difficult to imagine.

(8) Intelligent Aliens will be moral. The cooperation apparent in all of the highly social species of the Earth is based on some degree of altruism and self sacrifice. It has arisen from natural selection at both the individual and the group levels and has led to our sense of morality. Presumably alien intelligences derived from similar group evolution would inherit a similar sense of morality.

(9) Intelligent Aliens skilled in genetic engineering will not have used genetic modification to significantly change their social nature. Our technological civilization has only very recently reached the beginnings of an ability to modify and manipulate the human genetic code. It is not difficult to imagine a future in which we take the human genome in hand and change it to eliminate genetic diseases and disease tendencies, to give us better memories, more intelligence, bodies better adapted to hostile environments, and more longevity. Perhaps we might even decide to take this process a step further and edit out the inherited "baggage" of instinctual behavior that we call "human nature". Wilson believes that we will not do this, and instead will choose to retain the inherently messy, self-contradictory, internally conflicted, endlessly creative human mind that exists today, and that similarly intelligent aliens will do the same. We and they will be existential conservatives.

    Another aspect of Wilson's book that should be of interest to SF readers is his assessment of the prospects for interstellar colonization. Wilson has serious reservations about the colonization by humans of the planets of other star systems. These reservations are similar to those expressed in Paul Davies' Afterword in the recent book Starship Century (in which I wrote a chapter on interstellar wormholes).

    Basically, any planetary ecology is a vast array of interacting virus, bacterial, plant, and animal life that, after many eons of natural selection and responses to random events, challenges, and catastrophes, has arrived at a stable system. The ecology of an alien world would necessarily be qualitatively different from that of Earth and would be wholly incompatible with our own ecology. The two worlds would necessarily have radically different origins, different molecular machinery, and would differ in fundamental ways, due to the endless paths of evolution that produced the inhabiting life forms.

    The typical grocery store contains only a tiny subset of the Earth's plant and animal material, a subset carefully selected to be edible and non-toxic. The vast majority of terrestrial organisms are unsuitable for human consumption. The organisms of alien planets would be much more so. Wilson argues that the problem of transplanting the Earth's ecosystem to another planet basically has no solution, that we must resign ourselves to living on the one planet we currently occupy, and that we should take better care of it if we wish to continue doing so.

    These discussions of intelligent aliens and interstellar colonization, while perhaps of most interest to SF readers, represent only a small fraction of Wilson's book. He displays his expertise in the study of social insects with fascinating details on the behavior of driver ants, leaf-cutter ants, termites, and bees. He addresses the "two culture" problem, the disconnect between the sciences and the humanities, by announcing and promoting the dawn of a New Enlightenment in which the new insights into provided by science on the origins and outlines of human nature can shape and encourage a new flowering of art, literature, and philosophy. He also takes on religion, describing it as an essentially destructive syndrome that exploits the tribal us-vs-them tendencies of human nature, promotes unreason, and ultimately causes good people to do bad things.

    Overall, The Meaning of Human Existence is an important contribution to our understanding of humanity and of our place on the Earth and in the universe. It is disturbing, thought provoking, fascinating, and highly recommended.


The Meaning of Human Existence, Edward O. Wilson, Liveright Publishing Corporation, NY (2014); ISBN: 978-0-87140-100-7.

Starship Century: Toward the Grandest Horizon,  Gregory and James Benford, eds., Microwave Sciences (2013); ISBN: 978-1-93905-129-5.

SF Novels by John Cramer:  my two hard SF novels, Twistor and Einstein's Bridge, are newly released as eBooks by Book View Cafe and are available at : .

AV Columns Online: Electronic reprints of about 177 "The Alternate View" columns by John G. Cramer, previously published in Analog , are available online at:

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