We have reached the end of the T&R series. In a truth and reconciliation process, truth is required for reconciliation. There must be a consensus on what happened, even if all wrongs cannot be righted. I have had my say on what happened during the group selection controversy. Anyone who wishes to challenge my account is welcome to do so. This period in the history of evolutionary thought deserves the same kind of scholarship that is lavished upon Darwin and his contemporaries. The more scholars the merrier. Much of what I have reported in the T&R series is drawn from my book with Elliott Sober, Unto Others, which was published in 1998 and has largely withstood the test of time. I'd like to think that Samir Okasha, author of the highly respected Evolution and the Levels of Selection (2006), agrees with my account. If not, I hope he will speak up.
Once a consensus is reached on what happened, scientific inquiry can proceed in a more unified fashion than before. I end this series with a summary of what a fully reconciled field of sociobiology will look like. For a more detailed account, please consult my 2007 article co-authored with E.O. Wilson titled "Rethinking the Theoretical Foundation of Sociobiology."
1) The original problem is the fundamental problem of social life. Darwin put his finger on the key problem with the evolution of social adaptations. Traits that are "for the good of the group" are not necessarily locally advantageous. If they evolve, it is not because individuals bearing the trait survive and reproduce better than individuals bearing alternative traits in their immediate vicinity. This deserves to be recognized as the core problem of sociobiology.
2) There is only one solution to the original problem. If a trait is locally disadvantageous wherever it occurs, there is only one way for it to evolve in the total population--by being advantageous at a larger scale. Groups of individuals displaying social adaptations must survive and reproduce better than other groups, to counterbalance the disadvantage of the same adaptations within groups. All evolutionary theories of social behavior embody this logic. The groups and fitness differentials within and among groups are there for anyone to see, once one knows what to look for.
3) Selection within and among groups are factual matters, not matters of perspective. Once the groups relevant to the evolution of a particular trait are identified (something that all models of social behavior must do), selection within and among groups can be straightforwardly measured--in a model, experiment, or nature. The question of whether a given trait evolves on the strength of within-group selection, between-group selection, or a combination or both has an answer upon which everyone can agree.
4) The categorical rejection of group selection in the 1960s was an error, pure and simple. It is simply not the case that lower-level selection invariably trumps higher-level selection. Period. End of discussion. Textbooks and other accounts that imply otherwise need be revised. The erroneous rejection of group selection was especially tragic because it made the only solution to the original problem appear wrong, motivating a search for other solutions that in retrospect turned out to be the only solution in disguise. Why would anyone want to perpetuate this confusion once it is seen clearly?
5) If it walks like a duck and quacks like a duck, maybe it's a duck. Avoiding a stigmatized term makes sense as a short-sighted strategy for avoiding controversy, getting your article published, etc., but it is no way for a scientific discipline to conduct itself. If scientists aren't going to keep careful track of what was said and meant during the history of a given subject, who will? Failing to mention group selection when discussing issues that have always been central to the group selection controversy is poor scholarship and should be grounds for rejection in a peer review journal.
6) Derived issues associated with the group selection controversy should not be confused with the original problem. From Darwin to Dawkins, group selection has been centered on the original problem, as I have shown in considerable detail. During the last few decades, however, a number of other issues have arisen. The first thing we need to know about these derived issues is that they do not bear upon the original problem. Secondly, we need to evaluate them on their own merits. A short list of derived issues includes the following.
7) My formula is better than yours. Given the same set of biological assumptions about the evolution of a given trait, there is more than one way to calculate what evolves in the total population. Some methods highlight local fitness differentials in addition to the global outcome. Other methods report only the global outcome, for example by averaging the fitness of individuals across groups or the fitness of genes across all contexts. Since all of the methods make the same biological assumptions, the differences between them are empirically empty, as Andy Gardner put it (see T&R XVIII). Nevertheless, one might be preferable to another based on other criteria, such as the compactness of the formula or certain insights that are highlighted by some formulations and obscured by others. For example, Hamilton's original formulation of inclusive fitness theory obscured the fact that altruism is locally disadvantageous even in family groups, which jumps out of the Price equation. However, the Price equation can misclassify a nonsocial trait that evolves by pure individual-level selection (e.g., type A has a fitness of 1 and type B has a fitness of 0.75, no matter how they are grouped) as an example of group selection when the types are clustered into separate groups. The empirically empty preference of one formulation over another should never be confused with the empirically meaningful issues associated with the original problem.
8) Type one vs. type two group selection. Some traits, such as altruism, can be measured in individuals. Other traits, such as group size, can only be measured in groups. Samir Okasha refers to these as type 1 and type 2 traits, respectively. Whatever the merits of this distinction, it is important to realize that virtually all of the examples of group selection discussed throughout its history have been of the type 1 variety--traits that can be easily measured in individuals but require group selection to evolve because they are locally disadvantageous. A trait need not be a "group-level" trait (type 2) to evolve by group selection. Conversely, a "group-level" trait such as group size can evolve by pure within-group selection, as we saw in T&R XVIII for the endangered bird species discussed by Hanna Kokko.
9) Everything that evolves as a form of individual selfishness. Whenever altruism evolves by group selection, the average altruist is more fit than the average non-altruist in the total population, which can be conceptualized as a form of individual selfishness. The same gambit allows individual-level adaptations to be conceptualized as a form of gene selfishness. The problem with these expanded definitions of selfishness is that they don't deny what they seem to deny. Gene selfishness is no argument against group selection and neither is the fitness of individuals averaged across groups. Theoretical biologist Alan Grafen is going to great lengths to build a formalism in which natural selection operating at all levels of the biological hierarchy (in multilevel selection terms) can be represented as a form of fitness maximization at the individual level. Strictly speaking, this enterprise is doomed to failure because natural selection operating below the level of the individual, resulting in such things as cancer and meiotic drive, can never be represented as for the good of the individual. Thus, Grafen must assume that these examples are trivial to proceed with his agenda. Even then, however, what is the point of trying to represent natural selection as a maximizing process at a single level of the biological hierarchy, much less the individual level?
10) Group selection vs. group adaptation. Generations of students have been told to avoid "for the good of the group" thinking because it requires group selection. Another way to say "for the good of the group" is "group-level adaptation". Nevertheless, according to a recent article by Andy Gardner and Alan Grafen, a trait does not count as a group-level adaptation just because it evolves by group selection; it must evolve almost exclusively by group selection. It's amazing how fast this argument has been taken up as the newest defense of individualism in evolutionary thought. Critics and proponents of group selection alike would have been mystified by it in the 1960s. For them, the question was whether group selection ever happens. The idea of restricting the concept of group-level adaptation to cases where group selection only happens would never occur to them. It shouldn't be necessary, but Elliott Sober and I are preparing to spell this out in yet another article as the academic arms race continues.
It's worth asking why so many derived issues have arisen after the original problem was settled. In the spirit of discussing cultural influences for current science rather than waiting 50 or 100 years, (see T&R VI), I submit that when the rejection of group selection failed, those drawn to individualism felt the need to produce new arguments on its behalf. All of the derived issues buttress the concept of the individual as a privileged level of the biological hierarchy. Individualism is the primary issue at stake and when one argument fails, others are created to take its place. Once we let go of individualism, these arguments seem pointless and contrived. Adaptations can evolve at all levels of the biological hierarchy, from genes to ecosystems, but only when certain conditions are met. Truth and reconciliation for group selection means regarding this statement in a positive sense and exploring its rich implications.
Reading this series of blogs—which I had not done for a long time—was a poignant experience. Bear in mind that my first article on group selection was written 35 years earlier in 1975. Now here I am, still at it twelve years later, for a total span of 47 years.1 That’s 29% of the history of evolutionary thought, starting from the publication of Darwin’s On the Origin of Species in 1859!
Don’t get me wrong. Progress has been made during the last 12 years and the trend is not in doubt. Still, there’s no getting around the fact that the history of MLS theory is bound up with larger cultural trends, such as Individualism, which span academic disciplines and popular culture. People must hear about it from other people, which is often impeded by disciplinary barriers. Then they must relate the new ideas to their current milieu of ideas, which is likely to be a complex interaction. Time is required for all of this to happen and twelve years can go by pretty fast.
In this epilogue, I will provide a brief progress report on where things currently stand.
MLS and real-world change efforts. My most recent statement on MLS theory was an online lecture titled “Multilevel Selection Theory: Past, Present and Future,” delivered on November 2 2021 to a newly formed group called the Darwin Club. This group says as much about the current status of MLS theory as the content of my lecture. It was founded by Geoffrey Hodgson, who is an eminent scholar of economics, the social sciences, and Darwinian thought. In his own work, Hodgson notes that the word “evolution” has always had a broader meaning than the specifically Darwinian emphasis on variation, selection, and replication. This remains true within the modern social sciences. Even the economic school of thought known as evolutionary economics uses the term so loosely that there is no conceptual core.3 The Darwin Club was founded to place economics and the social sciences on the foundation of Darwinian evolution, which can be defined as any process that combines the three ingredients of variation, selection, and replication—no matter what the mechanism of replication.
If the application of specifically Darwinian evolution to economics and the social sciences is that new, then MSL theory as a topic that fits within Darwinian evolution is newer still. In other words, many members of the Darwin Club, while highly accomplished within their respective disciplines and embracing Darwinism in general terms, unsurprisingly did not yet know much about MLS theory. I therefore needed to provide a basic tutorial, not much different from my Truth and Reconciliation series, although for a more sophisticated audience.
If you have sufficient interest, I recommend that you view this lecture to compare it with my T&R series and listen to the Q&A following my talk. Nobody challenges MLS theory as a theoretical framework or the importance of higher-level selection in biological and human gene-culture coevolution. Those days are gone. Instead, the questions center on the many implications of MLS theory for a diversity of human-related topics, both academic and applied.
My own efforts during the last 12 years have been devoted to practical applications of MLS theory. Very simply, what I call “the original problem” in the T&R series and “stubborn facts” in my Darwin Club lecture must be dealt with in all real-world change efforts, just as in all academic theories of social evolution. All prosocial efforts directed toward the welfare of others or a society as a whole at a given scale are vulnerable to disruption by Darwinian processes operating at lower scales. Unless the potential for disruptive lower-level selection is suppressed—what’s known as a major evolutionary transition in genetic evolution—then higher-level social units such as businesses, cities, nations, or the whole earth will simply fail to exist as functionally organized units.
My collaboration with Elinor Ostrom is a case in point.4 A political scientist by training, Ostrom was awarded the Nobel Prize in economics in 2009 for showing that groups are capable of managing common-pool resources, avoiding the famous “tragedy of the commons”, if they implement certain core design principles (CDPs). In my collaboration with Ostrom and her postdoctoral associate Michael Cox (now a professor at Dartmouth College), we generalized the CDPs from a MLS perspective. Three implications are: 1) What Ostrom showed for a certain kind of group should be expected for all cooperative endeavors; 2) The CDPs are scale-independent and needed to govern relations among groups in addition to relations within groups; 3) Groups can be coached in the CDPs to improve their efficacy. The nonprofit organization that I helped to form, Prosocial World, is putting this possibility into action.5
Another case in point is a forthcoming article co-authored with the economist Dennis Snower titled “Rethinking the Theoretical Foundation of Economics",6 which builds upon my 2007 article with Edward O. Wilson titled “Rethinking the Theoretical Foundation of Sociobiology".7 In both cases, MLS theory is advanced as the paradigmatic alternative to individualistic accounts of evolution (my collaboration with Wilson) and economics (my collaboration with Snower).
These examples illustrate two major points. First, MLS theory is continuing to prove itself as a theoretical framework centered on Darwin’s “original problem”. Second, MLS theory is only just coming to the attention of economists, other social scientists, and change agents of all stripes. There is no mistaking the trend, but there is still a long way to go.
MLS and the human evolutionary story. Acceptance of MLS theory has become more widespread for the academic study of human genetic and cultural evolution. It is now the majority view that small-scale human groups are much more cooperative than most primate groups, including our closest chimp and bonobo relatives (with bonobos more cooperative than chimps). A major factor in the evolution of human cooperation was social control—the ability of groups to collectively suppress bullying and other disruptive self-serving behaviors among their members. In MLS terms, social control is nothing more or less than a major evolutionary transition—the suppression of disruptive lower-level selection so that higher-level selection becomes the main evolutionary force8.
Increasingly, almost everything distinctive about our species is being seen as a form of cooperation—including our capacity for symbolic thought. Maintaining an inventory of symbols with shared meaning and transmitting them across generations is inherently a cooperative endeavor. Once cultural transmission became a full-blown stream of inheritance, it coevolved with genetic evolution up to the present day. Far from genes “holding culture on a leash” (a metaphor popularized by E.O. Wilson), human populations first adapt to their environments by cultural evolution, with the slower process of genetic evolution playing a following role (e.g., the genetic evolution of lactose tolerance after some human population began using milk as an adult resource by cultural means).
Cultural evolution is a multilevel process, no less than genetic evolution. In other words, a cultural trait might spread by benefitting some individuals relative to others within the same group, some groups relative to others within a multi-group population, and so on. It’s even possible for a cultural trait to spread like a disease, without benefitting either human individuals or groups. Empirical research is required to evaluate these different possible outcomes of cultural evolution, along with nonadaptive outcomes of evolution such as byproducts, mismatches, and drift.
What this empirical research shows is that higher levels of selection are a very strong force in human cultural evolution, accounting for a net increase in the scale of human societies over the last 10,000 years.9 This has been a zig-zag process, however, with disruptive lower-level selection an ever-present danger, just as cancer is an ever-present danger for multicellular organisms over hundreds of millions of years. What is now becoming clearly seen as a multilevel cultural evolutionary process operating over human history is also operating all around us in the present, once we know what to look for--returning us to MLS theory as essential knowledge for stewarding our cultural evolution into the future.
MLS and evolutionary biology. I have been spending so much of my time on MLS in relation to human evolution and practical applications that I do not feel in touch with developments in evolutionary biology over the last 12 years. The concept of major evolutionary transitions appears to have become mainstream and correctly interpreted as higher-level selection dominating lower-level selection.
Then there is the dawning awareness that every multicellular organism is not just a collection of largely identical genes but also a diverse microbial ecosystem (the microbiome). This means that the simple story of individual-level selection has become a more complicated story of individual-microbiome co-evolution. Terms such as holobiont selection are being coined to describe this possibility, but I have not read the literature sufficiently to know whether the ideas are being properly related to MLS theory.
In general, my sense is that the study of social evolution in non-human species is still in theoretical disarray. The mess that I describe in part VII of the T&R series still hasn’t been cleaned up. Hardly anyone outright rejects MLS as a legitimate theoretical framework or denies that higher-level selection can be a significant evolutionary force, but they still don’t see the clarity of what I call the “original problem” and how it is embedded in all theories of social evolution. Like the example of lion prides described in part XV of T&R, examples of social evolution continue to be described that invoke group selection in every way except using the words.10 New constructs are invented such as “fitness interdependence” and “self-domestication”, without being related to past constructs. Some theoretical formulations have become so esoteric that they have lost their capacity to inform empirical research.
I cannot effectively level these criticisms, however, without doing my own due diligence as a scientist and scholar. For me, the best news is that we don’t have to wait for these academic disputes to resolve to begin making a positive difference in the real world. MLS theory is already proving its worth on that front, which is where my own main effort will be directed.
 My 2015 book Does Altruism Exist? Culture, Genes, and the Welfare of Others provides a concise (150pp) “post-resolution” account of MLS theory. A sample of my online articles on MLS theory written since 2010 includes: What MLS Theory Tells Us About Free Speech, The Origins of Multilevel Selection Theory (with Elliott Sober),Master Class: A Conversation with Jonathan Birch About the Equivalence of Theories of Social Evolution, Group Selection in Every Way Except Using the Words: A Critique of The Goodness Paradox by Richard Wrangham, Systems Engineering as Cultural Group Selection: A Conversation with Guru Madhavan, and Reaching a New Plateau for the Acceptance of Group Selection.
 Hodgson, G. M. (2019). Evolutionary Economics: Its Nature and Future. Cambridge University Press.
 Wilson, D. S., Ostrom, E., & Cox, M. E. (2013). Generalizing the core design principles for the efficacy of groups. Journal of Economic Behavior & Organization, 90, S21–S32. https://doi.org/10.1016/j.jebo.2012.12.010
 Atkins, P. W. D., Wilson, D. S., & Hayes, S. C. (2019). Prosocial: Using evolutionary science to build productive, equitable, and collaborative groups. New Harbinger.
 Snower, D.J. and Wilson, D.S. (forthcoming). Rethinking the Theoretical Foundation of Economics.
 Wilson, D. S., & Wilson, E. O. (2007). Rethinking the theoretical foundation of sociobiology. Quarterly Review of Biology, 82, 327–348.
 Boehm, C. (2011). Moral Origins: The Evolution of Virtue, Altruism, and Shame. Basic Books.
Turchin, P. (2015). Ultrasociety: How 10,000 years of war made humans the greatest cooperators on earth. Baresta Books.
 For a recent example, see my critique of Richard Wrangham’s book The Goodness Paradox cited in footnote 6. This critique does not detract from my admiration for Wrangham’s work as a whole, appropriately interpreted.