Cameron Smith last joined us just over a year ago with an essay on human interstellar migration in the context of biological evolution. Here he turns to issues of culture and change over time. An anthropologist and prehistorian at Portland State University in Oregon, Dr. Smith brings insights he has gained in the study of the early human experience on Earth to the manifold problems confronting us as we head for the stars. His current work on interstellar issues is part of his engagement with Project Hyperion, an attempt by Icarus Interstellar to develop parameters and reference studies for a multi-generational worldship. Be aware of Dr. Smith’s excellent recent volume Emigrating Beyond Earth: Human Adaptation and Space Colonization (Springer-Praxis, 2013), and ponder the synergies that occur between the study of past human migrations and the ongoing cultural and biological evolution of a species aspiring to leave the world that gave it birth.

by Cameron M. Smith, PhD


1. Biological and Cultural Evolution

Any change in the heritable properties of a population over generations is evolution, and we can be sure that the human genome will evolve on multigenerational interstellar voyages, just as it continues to evolve here on Earth today. Even in relatively short, 5-generation voyages, a relatively small gene pool for humanity would have to be carefully composed to prevent collapse in the form of a demographic ‘extinction vortex’ following, for example, a catastrophic plague. This is all clear from elementary population genetics, as I pointed out recently in a technical article in Acta Astronautica1—and it’s important to note that not only will we have to be careful to ensure the genetic health of humanity, but also that of all our plant and animal domesticates and symbionts.2

And, we must remember that genetic information is, in the human lineage, only one channel or stream of adaptive, evolving information; another is culture.3 Culture evolves as surely as biology; like genes, information is replicated (culturally, in the form of ideas), varies in its expression, and those variable expressions of ideas do not all survive to be transmitted to the next generation, but some are more-often copied than the rest; culture, then, does not merely change by a process analogous to biological evolution, it does indeed evolve, albeit in its own way.4 While natural selection has not been entirely buffered out with technology, in human cultural evolution it has largely been replaced by ‘cultural selection’; two examples on opposite ends of a spectrum of selection are propaganda, the deliberate spread of certain information in a population, and censorship, deliberate prevention of the spread of such information. While these are driven by conscious motives, a significant difference from natural selection, which has no intent or purpose, these remain selection in that they alter the frequency of ideas in a culture, and shape its history.

2. How Will Human Culture Evolve Beyond Earth?

We can be sure that our genome will be shaped by new conditions, and some such adaptations, to new gravity environments for example, may be predicted based on what we know of human genetic diversity and adaptability. Can we say anything similar about how human culture might evolve? We can, but we must remember that culture change is much more rapid than biological change. With mass media, an idea can be presented to, and affect the behavior of, billions of people in a matter of seconds. For this reason, culture change is more historically contingent and less orderly, we might say, than biological change. But human behavior is not random, and there are patterns.

For example, in all human cultures a number of basic issues must be solved for sheer survival; an individual needs certain quantities of calories, fresh water and nutrients daily, and the way these are obtained can be strongly conditioned by the immediate resource environment. This has led to humanity, worldwide, developing or evolving cultural traits—”human universals”—that reflect basic problem-solving for the kinds of life form that we are, biologically and socially. An example of this is our subsistence mode. While this differs widely in detail worldwide, all humans have solved basic subsistence needs in one of four main modes of subsistence; foraging (hunting and gathering), pastoralism (raising domesticated animals), horticulture (low-intensity farming and animal domestication) or agriculture (intense farming with complex irrigation and animal domestication). These work for humanity, as opposed to, for example, photosynthesis (not available to [directly] process energy in most animal life). And, the mode of subsistence strongly conditions many cultural variables; for instance, foraging people are normally rather egalitarian, with few instances of social ranking, while among horticulturalists and agriculturalists, social ranking (inequal access to resources by population members) is common. In this case, elementary issues such as social ranking ethos are strongly conditioned by subsistence mode. There are plenty of other factors that play into the shape of a culture, and responsible anthropologists are careful not to be ‘ecological determinists’. But we can learn from such cases.

3. Where to Begin? ‘Human Universals’

Where to begin? It’s easy to be overwhelmed when we begin to think about how human culture will change on multigenerational voyages. To order my thoughts, I have begun to tackle this issue by researching the above-mentioned “human universals”. Again, these are domains of behavioral regulation common to all human cultures. For example, all cultures, in one way or another, regulate sexual behavior, and incest in particular. All human cultures also have basic moral systems for dealing with truth-telling, property theft, and killing. And all human cultures have distinctive languages, styles of bodily decoration, family structure and so on. Remember, the ways that these issues are solved differs by culture (leading to tremendous cultural diversity worldwide), but a set of universal cultural facets is a good place to start when we consider what we might expect to evolve beyond Earth. Table 1 displays some universal cultural domains (over 50 have been identified by anthropologists5), explains the concept of the domain, and provides an example of some alternatives.

Table 1. Common Cultural Domains

LanguageSpecific spoken and gestural (bodily) systems of communication, including vocabularies and grammars.Some languages assign gender to nouns, while others do not.
EthicsConcepts of right and wrong, justice, and fairness.Some cultures execute murderers, while others do not.
Social RolesRights and responsibilities differ by categories such as age (child, adult), gender (man, woman), and status (peasant, King).Cultures differ in the ages at which people take on certain rights and responsibilities, and specifically what those rights and responsibilities are.
The SupernaturalConcepts regarding a universe considered fundamentally different from daily experience.Different cultures worship different gods, goddesses, and other supernatural entities.
Styles of Bodily DecorationHuman identity is often communicated by bodily decoration, either directly on the body or with clothing.Some cultures heavily tattoo the body while others communicate identity more with clothing styles
Family StructureConcepts of kinship or relations between kin, and associated ideas such as inheritanceSome cultures are polygynous, where males have several wives, and some are polyandrous, where females have several husbands.
Sexual BehaviorRegulation of sexual behavior, including incest rules.Cultures differ in the age at which sexual activity is permitted.
Food PreferencesConcepts of what are appropriate food and drink in certain situations.Some cultures eat certain animals while others consider them unfit to eat.
AestheticsConcepts of ideals, beauty, and their opposites.Some cultures value visual arts more than song, and vice versa.
Ultimate Sacred PostulatesCentral, unquestionable concepts about the nature of reality.Some cultures consider time to be cyclic while others consider it linear.

Rather than generally cast about, then, grasping for what might change over generations of human cultural evolution during future voyages to distant worlds, each of us guided by our own specific ideas and interests, we can systematically use the tools of anthropology and the principles of evolutionary theory to make useful predictions and recommendations to care for the cultural health of interstellar migrant populations.

Such recommendations are often considered ‘meddling’ or ‘social engineering’ by critics, but of course every new law we pass, every tradition we begin to follow, every marriage we sanction or disallow is ‘social engineering’. I take the view that rather than interfering with ‘natural’ culture change, such informed regulation of culture would make for a better future (especially for future human voyagers) than if we left things to ‘fate’. That could too easily go wrong, as we see in the last century of global warfare, where civilization is a thin veneer, nothing more than a set of agreements that, once and easily breached, result in conflict. Thinking clearly about what might befall future generations is not social engineering, it is taking care of the future, as we do by purchasing insurance individually, or working to ensure universal human rights by the passage of international regulations on certain behaviors.6

4. Two Guidelines for Multigenerational Cultural Health

As mentioned, currently I have no clear recommendations, but I am working on many in my research for a forthcoming book, (tentatively titled Principles of Space Anthropology). For example, while we cannot be certain how the regulation of sexual behavior, a cultural universal, will play out in detail off-Earth, we can be certain that it will be adjusted to accommodate a lower population growth rate than we have in many areas of Earth today. If interstellar voyagers are to emphasize no, or very low population growth for some generations, for instance, social institutions and sanctions might well be used to delay impregnation until somewhat later in life than we see, for example, in developed countries today. Marriages themselves might be carried out at a substantially later age than we are accustomed to, and out-of-wedlock births might be significantly discouraged by social means. In one way or another, the finite size and resources of the interstellar vehicle or vehicles would demand a low-or-no population growth ethos for some centuries, and this would surely affect reproductive rights and result in some kind of regulation of sexual behavior. How do we decide what recommendations to make for planning interstellar voyaging? I have at least two guiding principles that will help condition my own recommendations.

First, human culture, and evolution in general, do not typically tolerate rapid and significant structural change. There are many reasons for this, including the fact that bodies and cultural values are somewhat tailored to modern or even ancient conditions, and radical change on a short scale might well dissolve the close connection between the anatomical or cultural feature and the environmental variable. For this reason, I tend not to recommend new and radical social structures or other arrangements for interstellar voyages. Rather, I think it will be best to use social and cultural arrangements that have been familiar to humans for thousands of years; people should not be arranged, then, in new kinds of family structure, or unfamiliar housing such as ships’s barracks, but as families living in familiar environments including villages and towns connected by travel routes that pass through uninhabited areas.

Second, concerning the populations of interstellar vessels, I strongly believe that we should go in large numbers rather than small, barely-sufficient numbers. While some human populations have been able to survive for centuries in the low hundreds, even cut off from other breeding populations, such cases are exceptions to the rule that human populations are interlinked, yielding genetic populations not of just hundreds of individuals, but multiple thousands. This accords with what we see in vertebrates in general, and mammals and primates in particular, where natural and genetically healthy populations rarely drop below 5,000. I also recommend doubling or tripling the outsetting population to guard against the possibility of catastrophe; plague is a particularly terrifying spectre for enclosed populations, and just as passenger aircraft wings are engineered to take not 3 g’s but 10 or more g’s before failure, safety margins should be built into such plans. Since populations alone can significantly affect the shape of cultural universal adaptions, these must be considered together.

The prospect of interstellar voyaging to spread and preserve humanity and civilization is too great a leap for some to make; they call it ‘pie in the sky’, ‘irresponsible dreaming’, ‘escapism’ and plenty else. My anthropological perspective suggests these are all pessimistic critiques from people lacking in creativity or foresight—or even the hindsight that reveals the ruins of each of the ancient civilizations. I am thrilled to be working with Icarus Interstellar to slowly assemble the puzzle pieces required to provide the breathtaking option of long-term space settlement for humanity over the next 100 years.


1. Smith, C.M. 2014. Estimation of a Genetically Viable Population for Multigenerational Interstellar Voyaging: Review and Data for Project Hyperion. Acta Astronautica 97(2014):16-29 (abstract).

2. Xu, J. and J.I. Gordon. 2003. Honor thy Symbionts. Proceedings of the National Academy of Sciences 100(18):10452-10459.

3. Whiten, A., R.A. Hinde, K.N. Laland and C.B. Stringer. 2011. Culture Evolves. Philosophical Transactions of the Royal Society B (366):938-948.

4. Gabora, L. 2013. An evolutionary framework for culture: Selectionism versus communal exchange. Physics of Life Reviews 10(2): 117-145.

5. Brown, D.E. 1991. Human Universals. Philadelpha, Temple University Press.

6. For example, see the United Nations’ Universal Declaration of Human Rights, and its use of sanction in many cases to ensure them. Though the UN can be ineffective, its very existence at least demonstrates the will to work in union for the betterment of all.