Extraterrestrial Evolutionary Psychology

Many aspects of the SETI/METI debate bear on our personal beliefs about the nature of intelligent beings,” writes David Brin, and this is certainly true. He goes on to ask whether “our favorite models of ‘human nature,’ including the importance of individuality, apply equally to a sapient race descended – say – from pack carnivores, like wolves? Or solitary hunters, like tigers?” So far so good. But then he leaps into a premature discussion of whether our extraterrestrials will be libertarians, and whether they will be organized in a feudal-type society or a diamond-shaped one. My response will explain why his invoking Darwin is a good beginning, but that we need a lot more Darwin before we can explore extraterrestrial social-political organization. The ideas below are based on and expanded from my previous discussions of what kinds of extraterrestrial intelligences are at least scientifically possible and perhaps even likely (Barkow 2000, 2013).

Any species we can communicate with obviously has a high technology. That fact implies that it is a social, cooperative species with some form of cultural capacity. “Culture” refers to a vast information pool that is socially transmitted both within and between generations, with knowledge generally accumulating over time. A solitary, non-cultural species, no matter how intelligent its individuals, is highly unlikely to accumulate the knowledge needed to devise the technology that enables interstellar communication. (And why would a member of such a species be interested in interstellar communication, anyway?)

How did we evolve our own cultural capacity? Many species have considerable intelligence and engage in much social learning (e.g., chimpanzees, elephants), but only our line has evolved anything like human-level capability. There must have been amplifying processes, during our evolution, which led to our intelligence and reliance on culture. Two important intelligence/culture amplifiers for our species would have involved sex and predation.

By “sex” I mean sexual selection or mate choice. Extraterrestrials are very likely to have two sexes for technical reasons that space limitations prevent me from discussing here. But see Barkow (2000). Species typically evolve some traits not primarily because they help the individual adapt to the local environment but because they increase the odds of mating with a “good genes” individual. The peacock’s feathers are an accurate indicator of health and therefore of good genes, and they attract the female of the species. The antlers of the male elk permit it to compete for dominance with other males, with the winners gaining sexual access to fertile females. Offspring resemble their parents, as Darwin taught, so these traits come to typify the species in question. For humans, research has shown that both females and males tend to prefer sexual partners with intelligence and skills (along with other characteristics, of course). Presumably, during our evolutionary history, traits that made potential mates more attractive included the ability to learn readily from others and to acquire and improve upon the social and technological skills needed for gathering and hunting, food preparation, child care, sociality, and for creating the implements necessary for these activities. These attractive people would have had more surviving offspring than the unattractive (the stupid, the uncooperative, the unskilled). If ever we communicate with extraterrestrials, we will learn a lot if we can discover what they find sexy.

The evolutionary psychologist Geoffrey Miller (2000) has argued that art, literature, large vocabulary, sports, and just about any domain in which we compete in terms of a standard of excellence, are all ways in which we show off our “good genes” to potential mates. So if our extraterrestrials are in part intelligent due to sexual competition (mate choice), they may seek to impress us with works of art or simply non-functional elaboration of tools of any kind, and they are likely to appreciate our own forms of art, or at least to recognize our art as art.

Predation is another amplifying process that would have contributed to our evolution. Predation involves culling. Individuals with certain traits – or who lack certain traits – are removed from the evolutionary line, because death prevents reproduction. Predation can be a reciprocal process in which, say, the owl culls the local rabbit population of individuals who are poor at freezing and hiding, while the rabbits in effect cull (by starvation) those owls with poor eyesight or who cannot detect small movements. During our own evolution, ancestral humans probably culled each other, destroying individuals in rival kin groups or bands. Those poor in cooperating with their fellows (say, on raiding sorties) or who could not readily learn subsistence or defensive/offensive skills or how to care for children and infants were less likely than were others to leave descendants. (Of course, the successful were also more attractive sexually than were those who barely survived.)

Predation can also occur at the group level, especially when the groups are groups of kin. Our capacity for ethnocentrism and the alacrity with which we split into antagonistic in-groups and out-groups suggest (in a somewhat circular manner) that groups with the genetic capacity to create and transmit more effective culture and cooperation were the ones that defeated their rivals and became our ancestors. Suppose our extraterrestrials also evolved in this manner, at least in part. That means that they will tend to be ethnocentric, and our communication with them should therefore emphasize our friendliness.

But suppose, instead, that their history of predation involved not competing bands of their own species but competition with a rival species (mutual culling predation). Their intelligence and cultural capacity would be heavy on defense and offense. Worse, they might well have developed an automatic, unthinking hostility to members of other intelligent species. They would be obligate xenophobes who would consider peace with aliens insanity. Their version of SETI could involve a search for enemies! Proactively sending messages to them could be highly dangerous. We would be well-advised to provide no information about our physical form in order to have the option of convincing our listeners that we are members of their own species.

The evolutionary psychology of a species must affect its sociology and political organization. For example, think of our communicating with an ancient species in which only those who conform get to breed, only those who readily learn to behave properly get to procreate, while the nonconformists are neutered or even killed. This enduring eugenics policy would result in a process called the genetic assimilation of culture. Eventually, individuals would almost automatically learn their culture and the behaviors expected of them, and the result would be a society that changed only very slowly (and would be vulnerable to unanticipated environmental change, but that is another story). They could even be considered genetic libertarians because they would have little need of external pressures to make them behave “properly” – acting otherwise would be literally unthinkable. They would not need much in the way of government regulation, and police would be unnecessary.

Here is another example of the importance of evolved psychology for social/political structure. A powerful aspect of our psychology is that we want more for our own children than we do for the children of others. In the small-scale, largely hunting-gathering societies in which we evolved, other people would “level” – act against – any single individual who tried to dominate others. Moreover, there was no way in which high rank could be hereditary, no way to leave superior hunting or leadership or story-telling abilities to one’s own children alone. All this changed once we developed agriculture and herding and now had goods that could be accumulated and passed on to our own children and no one else’s. Now we could and did develop massive social inequality, as Brin points out.

Suppose, however, that our extraterrestrials do not know whose children are whose and have no concept of parenthood. Perhaps the young hatch independently like frogs and insects, and only at the second or third developmental stages do they begin social learning. The resulting society might have the transitory social inequality of our own hunting-gathering ancestors, but it could hardly develop feudalism. The species’ evolutionary psychology would produce a sociology unfamiliar to us, one without the possibility of hereditary social inequality or stratification.

Before we can address issues of extraterrestrials and social-political organization and philosophy, we need to unleash the evolutionary anthropologists and the behavioral ecologists and ask them to delimit the evolutionary psychologies we could find out there. Only then will we be ready to think about the sociologies and politics that beings with such psychologies could develop.

Finally, should we “shut the hell up”? Yes. The thought experiment suggests that there could be dangerous xenophobes out there, so I must agree with Robin Hanson. If we must yell we should be very, very careful about what we say, what we reveal, and how we present ourselves. Sending out non-representational art would probably be the safest message.



Barkow, Jerome H. (2000). Do Extraterrestrials Have Sex (and Intelligence)? In Dori LeCroy & Peter Moller (Eds.), Evolutionary Perspectives on Human Reproductive Behavior (Vol. 907, pp. 164-181). New York: Annals of the New York Academy of Sciences.

Barkow, Jerome H. (2013). Eliciting Altruism While Avoiding Xenophobia: A Thought Experiment. In Douglas A. Vakoch (Ed.), Extraterrestrial Altruism: Evolution and Ethics in the Cosmos. New York: Springer.

Miller, Geoffrey. (2000). The Mating Mind: How Sexual Choice Shaped Human Nature. New York: Doubleday.

Also from this issue

Lead Essay

  • David Brin criticizes the possibly reckless turn in recent SETI research. He also speculates on what the great silence may say about human societies. It may not be such a good idea to go about shouting to the cosmos - not when we have so little idea of what may be out there.

    That said, Brin speculates on the nature of any intelligent life we are likely to meet. He notes that our scientific and technological society is very unusual when compared to societies of the past: It is, he says, diamond-shaped, with relatively few at either the bottom or the top, and with a broad equality of social station, rights, and even wealth in the middle. Maintaining such a society is hard work, and one reason we seem to be alone in the universe may simply be that very few alien civilizations have escaped from feudalism or something like it.

Response Essays

  • Robin Hanson runs a cost-benefit analysis on our use of very loud radar signals. He finds that if there is even a small probability of a hostile civilization hearing us, then the risks are not worth the rewards. This conclusion holds up under fairly severe assumptions, and it grows much firmer as we consider our likely technological developments in the near future. Astronomy, moreover, is advancing rapidly, and it will likely tell us much more about the probability of existence and the nature of extraterrestrial life. When it does, we may have a better idea of the wisdom of sending out very loud radio signals. In the meantime, he concludes that yes, humanity should indeed shut the hell up.

  • We have few tools at our disposal to learn about intelligent extraterrestrials - if they even exist. But one relatively powerful tool is evolutionary psychology. Jerome H. Barkow reviews some findings from terrestrial evolutionary psychology and considers their implications for alien life. We will learn a lot if we can discover what aliens find sexy, he claims - because sexual selection has overwhelmingly influenced terrestrial animals, including ourselves.

    We will also learn a great deal by observing aliens’ predation history, their group cooperation, and their genetic transmission of culturally favored traits. Of course, these observations will have to wait for first contact. Barkow concludes by agreeing with Robin Hanson - until we know more, humanity should probably keep relatively quiet.

  • Douglas Vakoch argues that active SETI is not to be feared: If highly advanced civilizations exist out there, they will have highly advanced radio detection equipment. If they are anywhere near us, then they will have known about us for decades. Messaging them can do no more harm than what we have already done, and it may do us a great deal of good, particularly if these civilizations are waiting for us to make the first move, and if messaging them directly is the signal they need to initiate contact.