group selection hypothesis

• Subject List
• Take a Tour
• For Authors
• Subscriber Services
• Publications
• African American Studies
• African Studies
• American Literature
• Anthropology
• Architecture Planning and Preservation
• Art History
• Atlantic History
• Biblical Studies
• British and Irish Literature
• Childhood Studies
• Chinese Studies
• Cinema and Media Studies
• Communication
• Criminology
• Environmental Science

Evolutionary Biology

• International Law
• International Relations
• Islamic Studies
• Jewish Studies
• Latin American Studies
• Latino Studies
• Linguistics
• Literary and Critical Theory
• Medieval Studies
• Military History
• Political Science
• Public Health
• Renaissance and Reformation
• Social Work
• Urban Studies
• Victorian Literature
• Browse All Subjects

How to Subscribe

• Free Trials

In This Article Expand or collapse the "in this article" section Group Selection

Introduction.

• Origins of the Group Selection Controversy
• Population Genetics
• Price-Hamilton
• Quantitative Genetics
• Numerical Simulations
• Empirical Studies
• Sex Allocation
• Species Selection
• Group Adaptation and the Superorganism
• Major Transitions in Evolution
• Shifting Balance
• Cultural Group Selection

Related Articles Expand or collapse the "related articles" section about

About related articles close popup.

Lorem Ipsum Sit Dolor Amet

Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aliquam ligula odio, euismod ut aliquam et, vestibulum nec risus. Nulla viverra, arcu et iaculis consequat, justo diam ornare tellus, semper ultrices tellus nunc eu tellus.

• Cooperation and Conflict: Microbes to Humans
• Field Studies of Natural Selection
• Inclusive Fitness
• Kin Selection
• Natural Selection

Other Subject Areas

Forthcoming articles expand or collapse the "forthcoming articles" section.

• Bacterial Species Concepts
• Recombination and Evolution
• Selective Sweeps
• Find more forthcoming articles...
• Export Citations
• Share This Facebook LinkedIn Twitter

Group Selection by Andy Gardner LAST REVIEWED: 17 August 2022 LAST MODIFIED: 26 October 2023 DOI: 10.1093/obo/9780199941728-0101

The basic idea of group selection theory is that the logic of natural selection acting at the level of individual organisms can also be applied to the level of whole groups of organisms. Exactly what this means and whether it is a useful way of thinking about the biological world remains very controversial. Indeed, the development of the group selection literature often appears to have been driven as much by confusion and misstep as it has by informed reasoning. Although careful and considered foundations were laid in the nineteenth century by Charles Darwin, his contributions to the theory of group—or multilevel—selection were largely ignored and, in the twentieth century, gave way to a naïve view that ordinary natural selection leads inevitably to adaptation for the good of the species as a whole. Since the 1960s, progress has proceeded in fits and starts, with a gradual consensus building that adaptation at the level of whole populations requires that selection has been acting at a between-population level and that population-level adaptation tends to be eroded by the action of within-population selection. This development in understanding has led to an interest in conceptualizing and quantifying the action of selection at the between-group and within-group levels in a range of theoretical and empirical scenarios. However, no consensus has emerged as to how group selection and related concepts are to be formally defined. Accordingly, the theoretical literature is characterized by repeated returns to first principles and repeated reinvention of the wheel, rather than steady, cumulative, and collaborative progress. And this failure of theory has led to an empirical literature that is very patchy, with some neat studies in the laboratory and in the field being motivated and conducted within a multilevel selection framework but with little sustained progress through long-term interplay of theoretical and empirical research. As a research program, group selection has certainly enjoyed much less success than its competitor—the theory of kin selection—which appears to describe exactly the same phenomena in an alternative but exactly equivalent mathematical and conceptual language and has been shown to have enormous scientific utility in relation to biological topics as diverse as sex ratios, parasite virulence, and the evolution of altruism. But group selection does logically appear to provide a superior conceptual framework for understanding the evolution of group-level adaptation and so-called major transitions in individuality (e.g., from unicells to multicellular animals to eusocial insect “superorganisms”), and perhaps also the evolution of human culture, which, if it is Darwinian at all, may be best conceptualized as being a property rather of social groups and institutions than of individual persons. Moreover, group selection is of strong interest to philosophers and historians of biology, as well as to biologists of a philosophical and historical bent.

General Overviews

The literature on group selection has been inordinately focused on simply establishing what group selection is and whether it plays any meaningful role in the natural world. Multiple overviews have been published over the last sixty years, often in book form but also as influential review papers.

back to top

Users without a subscription are not able to see the full content on this page. Please subscribe or login .

Oxford Bibliographies Online is available by subscription and perpetual access to institutions. For more information or to contact an Oxford Sales Representative click here .

• About Evolutionary Biology »
• Meet the Editorial Board »
• Adaptive Radiation
• Amniotes, Diversification of
• Ancient DNA
• Behavioral Ecology
• Canalization and Robustness
• Cancer, Evolutionary Processes in
• Character Displacement
• Coevolution
• Cognition, Evolution of
• Constraints, Evolutionary
• Contemporary Evolution
• Convergent Evolution
• Cooperative Breeding in Insects and Vertebrates
• Creationism
• Cryptic Female Choice
• Darwin, Charles
• Disease Virulence, Evolution of
• Diversification, Diversity-Dependent
• Ecological Speciation
• Endosymbiosis
• Epigenetics and Behavior
• Epistasis and Evolution
• Eusocial Insects as a Model for Understanding Altruism, Co...
• Eusociality
• Evidence of Evolution, The
• Evolution and Development: Genes and Mutations Underlying ...
• Evolution and Development of Individual Behavioral Variati...
• Evolution, Cultural
• Evolution of Animal Mating Systems
• Evolution of Antibiotic Resistance
• Evolution of New Genes
• Evolution of Plant Mating Systems
• Evolution of Specialization
• Evolutionary Biology of Aging
• Evolutionary Biomechanics
• Evolutionary Computation
• Evolutionary Developmental Biology
• Evolutionary Ecology of Communities
• Experimental Evolution
• Founder Effect Speciation
• Frequency-Dependent Selection
• Fungi, Evolution of
• Gene Duplication
• Gene Expression, Evolution of
• Genetics, Ecological
• Genome Evolution
• Geographic Variation
• Group Selection
• Heterochrony
• Heterozygosity
• History of Evolutionary Thought, 1860–1925
• History of Evolutionary Thought before Darwin
• History of Evolutionary Thought Since 1930
• Human Behavioral Ecology
• Human Evolution
• Hybrid Speciation
• Hybrid Zones
• Hybridization and Diversification
• Identifying the Genomic Basis Underlying Phenotypic Variat...
• Inbreeding and Inbreeding Depression
• Innovation, Evolutionary
• Islands as Evolutionary Laboratories
• Land Plants, Evolution of
• Landscape Genetics
• Landscapes, Adaptive
• Language, Evolution of
• Latitudinal Diversity Gradient, The
• Macroevolution
• Macroevolution, Clade-Level Interactions and
• Macroevolutionary Rates
• Male-Male Competition
• Mass Extinction
• Mate Choice
• Maternal Effects
• Mating Tactics and Strategies
• Medicine, Evolutionary
• Meiotic Drive
• Modern Synthesis, The
• Molecular Clocks
• Molecular Phylogenetics
• Mutation Rate and Spectrum
• Mutualism, Evolution of
• Natural Selection in Human Populations
• Natural Selection in the Genome, Detecting
• Neutral Theory
• New Zealand, Evolutionary Biogeography of
• Niche Construction
• Niche Evolution
• Non-Human Animals, Cultural Evolution in
• Origin and Early Evolution of Animals
• Origin of Amniotes and the Amniotic Egg
• Origin of Eukaryotes
• Origin of Life, The
• Paradox of Sex
• Parental Care, Evolution of
• Parthenogenesis
• Personality Differences, Evolution of
• Pest Management, Evolution and
• Phenotypic Plasticity
• Phylogenetic Comparative Methods and Tests of Macroevoluti...
• Phylogenetic Trees, Interpretation of
• Phylogeography
• Polyploid Speciation
• Population Structure
• Post-Copulatory Sexual Selection
• Psychology, Evolutionary
• Punctuated Equilibria
• Quantitative Genetic Variation and Heritability
• Reaction Norms, Evolution of
• Reinforcement
• Reproductive Proteins, Evolution of
• Selection, Directional
• Selection, Disruptive
• Selection Gradients
• Selection, Natural
• Selection, Sexual
• Selfish Genes
• Sequential Speciation and Cascading Divergence
• Sexual Conflict
• Sexual Selection and Speciation
• Sexual Size Dimorphism
• Speciation Continuum
• Speciation Genetics and Genomics
• Speciation, Geography of
• Speciation, Sympatric
• Species Concepts
• Species Delimitation
• Sperm Competition
• Systems Biology
• Taxonomy and Classification
• Tetrapod Evolution
• The Philosophy of Evolutionary Biology
• Theory, Coalescent
• Trends, Evolutionary
• Wallace, Alfred Russel
• Privacy Policy
• Cookie Policy
• Legal Notice
• Accessibility

Powered by:

• [66.249.64.20|185.80.149.115]
• 185.80.149.115

December 18, 2008

Individual versus Group in Natural Selection

Does natural selection drive evolution at levels higher than selfish genes and fertile individuals?

By Steve Mirsky

Want to start a brawl at an evolution conference? Just bring up the concept of group selection: the idea that one mixed bag of individuals can be “selected” as a group over other heterogeneous groups from the same species. Biologists who would not hesitate to form a group themselves to combat creationism or intelligent design might suddenly start a pie fight to defend the principle that “it’s every man for himself.”

Yet Charles Darwin himself argued for group selection. He postulated that moral men might not do any better than immoral men but that tribes of moral men would certainly “have an immense advantage” over fractious bands of pirates. By the 1960s, however, selection at the group level was on the outs. Influential theorist George Williams acknowledged that although group selection might be possible, in real life “group-related adaptations do not, in fact, exist.”

Richard Dawkins of the University of Cambridge, whose writings have reached millions, maintains that selection might not even reach such a high level of biological organization as the individual organism. Instead, he claims, selection operates on genes—the individual is the embodiment of the selection of thousands of selfish genes, each trying to perpetuate itself.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

In the past few decades, however, group selection has made a quiet comeback among evolutionary theorists. E. O. Wilson of Harvard University and David Sloan Wilson (no relation) of Binghamton University are trying to give group selection full-fledged respectability. They are rebranding it as multilevel selection theory: selection constantly takes place on multiple levels simultaneously. And how do you figure the sum of those selections in any real-world circumstance? “We simply have to examine situations on a case-by-case basis,” Sloan Wilson says.

But the Wilsons did offer some guidelines in the December 2007 issue of Quarterly Review of Biology . “Adaptation at any level,” they write, “requires a process of natural selection at the same level, and tends to be undermined by natural selection at lower levels.”

Experiments with actual groups illustrate the point. Pseudomonas fluorescens bacteria quickly suck all the dissolved oxygen out of a liquid habitat, leaving a thin habitable layer near the surface. But some bacteria spontaneously develop a beneficial mutation. These group-saving individuals secrete a polymer that enables bunches of individuals to form floating mats. As a mat, all the bacteria survive, even though most of them expend no metabolic energy producing the polymer. But if the freeloaders get greedy and reproduce too many of their kind, the mat sinks and everybody dies, altruists and freeloaders alike. Among these bacteria, then, groups that maintain enough altruists to float outcompete groups with fewer altruists than that minimum number. The former groups survive, grow and split up into daughter groups. Thus, altruistic individuals can prosper, despite the disadvantage of expending precious resources to produce the polymer.

Perhaps the biggest change that group selection brings to evolutionary theory is its implication for so-called kin selection. What looks like group selection, some theorists argue, can actually be understood as genetic relatedness. Evolutionist J.B.S. Haldane pithily explained kin selection: “I would lay down my life for two brothers or eight cousins.” In this view, altruistic bacteria in the Pseudomonas mats are saving close relatives, thereby ensuring the survival of most of the genes they themselves also carry.

Turning that argument on its head, the Wilsons assert that kin selection is a special case of group selection. “The importance of kinship,” they note, “is that it increases genetic variation among groups.” The individuals within any one group are much more like one another and much less like the individuals in any other group. And that diversity between groups presents clearer choices for group selection. Kinship thus accentuates the importance of selection at the group level as compared with individual selection within the group.

The Wilsons think evolutionists must embrace multilevel selection to do fruitful research in sociobiology—“the study of social behavior from a biological perspective.” When doing so, other investigators can keep in mind the Wilsons’ handy rule of thumb: “Selfishness beats altruism within groups. Altruistic groups beat selfish groups.”

Note: This article was originally printed with the title, "What's Good for the Group".

Oxford University Press's Academic Insights for the Thinking World

Kin selection, group selection and altruism: a controversy without end?

Since 1964, BioScience has presented readers with timely and authoritative overviews of current research in biology, accompanied by essays and discussion sections on education, public policy, history, and the conceptual underpinnings of the biological sciences.

• By Samir Okasha
• January 29 th 2015

I recall a dinner conversation at a symposium in Paris that I organized in 2010, where a number of eminent evolutionary biologists, economists and philosophers were present. One of the economists asked the biologists why it was that whenever the topic of “group selection” was brought up, a ferocious argument always seemed to ensue. The biologists pondered the question. Three hours later the conversation was still stuck on group selection, and a ferocious argument was underway.

Group selection refers to the idea that natural selection sometimes acts on whole groups of organisms, favoring some groups over others, leading to the evolution of traits that are group-advantageous. This contrasts with the traditional ‘individualist’ view which holds that Darwinian selection usually occurs at the individual level, favoring some individual organisms over others, and leading to the evolution of traits that benefit individuals themselves. Thus, for example, the polar bear’s white coat is an adaptation that evolved to benefit individual polar bears, not the groups to which they belong.

The debate over group selection has raged for a long time in biology. Darwin himself primarily invoked selection at the individual level, for he was convinced that most features of the plants and animals he studied had evolved to benefit the individual plant or animal. But he did briefly toy with group selection in his discussion of social insect colonies, which often function as highly cohesive units, and also in his discussion of how self-sacrificial (‘altruistic’) behaviours might have evolved in early hominids.

In the 1960s and 1970s, the group selection hypothesis was heavily critiqued by authors such as G.C. Williams, John Maynard Smith , and Richard Dawkins . They argued that group selection was an inherently weak evolutionary mechanism, and not needed to explain the data anyway. Examples of altruism, in which an individual performs an action that is costly to itself but benefits others (e.g. fighting an intruder), are better explained by kin selection , they argued. Kin selection arises because relatives share genes. A gene which causes an individual to behave altruistically towards its relatives will often be favoured by natural selection—since these relatives have a better than random chance of also carrying the gene. This simple piece of logic tallies with the fact that empirically, altruistic behaviours in nature tend to be kin-directed.

Strangely, the group selection controversy seems to re-emerge anew every generation. Most recently, Harvard’s E.O. Wilson , the “father of sociobiology” and a world-expert on ant colonies, has argued that “multi-level selection”—essentially a modern version of group selection—is the best way to understand social evolution. In his earlier work, Wilson was a staunch defender of kin selection, but no longer; he has recently penned sharp critiques of the reigning kin selection orthodoxy, both alone and in a 2010 Nature article co-authored with Martin Nowak and Corina Tarnita. Wilson’s volte-face has led him to clash swords with Richard Dawkins, who says that Wilson is “just wrong” about kin selection and that his most recent book contains “pervasive theoretical errors.” Both parties point to eminent scientists who support their view.

What explains the persistence of the controversy over group and kin selection? Usually in science, one expects to see controversies resolved by the accumulation of empirical data. That is how the “scientific method” is meant to work, and often does. But the group selection controversy does not seem amenable to a straightforward empirical resolution; indeed, it is unclear whether there are any empirical disagreements at all between the opposing parties. Partly for this reason, the controversy has sometimes been dismissed as “semantic,” but this is too quick. There have been semantic disagreements, in particular over what constitutes a “group,” but this is not the whole story. For underlying the debate are deep issues to do with causality, a notoriously problematic concept, and one which quickly lands one in philosophical hot water.

All parties agree that differential group success is common in nature. Dawkins uses the example of red squirrels being outcompeted by grey squirrels. However, as he notes, intuitively this is not a case of genuine group selection, as the success of one group and the decline of another was a side-effect of individual level selection. More generally, there may be a correlation between some group feature and the group’s biological success (or “fitness”); but like any correlation, this need not mean that the former has a direct causal impact on the latter. But how are we to distinguish, even in theory, between cases where the group feature does causally influence the group’s success, so “real” group selection occurs, and cases where the correlation between group feature and group success is “caused from below”? This distinction is crucial; however it cannot even be expressed in terms of the standard formalisms that biologists use to describe the evolutionary process, as these are statistical not causal. The distinction is related to the more general question of how to understand causality in hierarchical systems that has long troubled philosophers of science.

Recently, a number of authors have argued that the opposition between kin and multi-level (or group) selection is misconceived, on the grounds that the two are actually equivalent—a suggestion first broached by W.D. Hamilton as early as 1975. Proponents of this view argue that kin and multi-level selection are simply alternative mathematical frameworks for describing a single evolutionary process, so the choice between them is one of convention not empirical fact. This view has much to recommend it, and offers a potential way out of the Wilson/Dawkins impasse (for it implies that they are both wrong). However, the equivalence in question is a formal equivalence only. A correct expression for evolutionary change can usually be derived using either the kin or multi-level selection frameworks, but it does not follow that they constitute equally good causal descriptions of the evolutionary process.

This suggests that the persistence of the group selection controversy can in part be attributed to the mismatch between the scientific explanations that evolutionary biologists want to give, which are causal, and the formalisms they use to describe evolution, which are usually statistical. To make progress, it is essential to attend carefully to the subtleties of the relation between statistics and causality.

Image Credit: “Selection from Birds and Animals of the United States,” via the Smithsonian American Art Museum .

Samir Okasha is Professor of Philosophy of Science at the University of Bristol, and co-author of " Kin Selection and its Critics " (BioScience, 65.1). He is the author of numerous articles and two OUP books: Philosophy of Science: A Very Short Introduction  and Evolution and the Levels of Selection , which was awarded the 2009 Lakatos Prize for an outstanding contribution to the philosophy of science.

• Earth & Life Sciences
• Science & Medicine

Our Privacy Policy sets out how Oxford University Press handles your personal information, and your rights to object to your personal information being used for marketing to you or being processed as part of our business activities.

We will only use your personal information to register you for OUPblog articles.

Or subscribe to articles in the subject area by email or RSS

Related posts:

No related posts.

Recent Comments

Dawkins’ book “The Selfish Gene” is about how selection is not at the individual level at all but at the GENE level.

Mr Okasha has missed this.

Because selection is at the gene level I would argue there is some individual selection and group selection as well in the sense that the genes in the body want to replicate themselves. By using what Dawkins calls “genesmanship” genes have evolved to recognise other bodies that have copies of themselves in community with other genes that work well to make that individual successful in reproduction. Kin selection results from recognising this compatibility on a gene level. The genes in a homogeneous group would favour altruism in that group because the copies of the genes would benefit from the group’s survival. The more genetically diverse the group the less altruism could help the genes in that individual’s body to preserve and increase copies outside of the individual – leading to a less innately social attitude in that individual.

[…] fittest individuals? Kin selection believes in the former. Group selection believes in the latter. Kin selection, group selection and altruism: a controversy without end? The answer to kin selection and group selection is probably a little bit of both in humans. Kin […]

[…] here’s the thing these people forgot.  Nature doesn’t just select for individuals.  If hyper-competitiveness was the way to the future, we would all be 8ft tall muscle bound rage […]

[…] us to be sociable. However, Denworth fails to mention the hotly debated attendant theory of “group selection,” which seems just as relevant to the genesis of friendship. According to this theory, the […]

[…] sociable. On the different hand, Denworth fails to claim the hotly debated attendant thought of “neighborhood desire,” which appears to be like factual as connected to the genesis of friendship. Based mostly fully […]

[…] us to be sociable. Nonetheless, Denworth fails to say the hotly debated attendant concept of “group selection,” which appears simply as related to the genesis of friendship. Based on this concept, the […]

Comments are closed.

Examples of Group Selection

• Living reference work entry
• First Online: 12 June 2018
• Cite this living reference work entry

• Carey Fitzgerald 3  

172 Accesses

• Group Selection
• Altruistic Punishment
• Multilevel Selection Theory
• Nectar Collection
• Eusocial Insect Societies

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Institutional subscriptions

Boyd, R., Gintis, H., Bowles, S., & Richerson, P. J. (2003). The evolution of altruistic punishment. Proceedings of the National Academy of Sciences, 100 , 3531–3535.

Article   Google Scholar  

Clutton-Brock, T. H., O’Riain, M. J., Brotherton, P. N. M., Gaynor, D., Kansky, R., Griffin, A. S., & Manser, M. (1999). Selfish sentinels in cooperative mammals. Science, 284 , 1640–1644.

Fehr, E., & Fischbacher, U. (2003). The nature of human altruism. Nature, 425 , 785–791.

Hamilton, W. D. (1964). The genetical evolution of social behavior. Journal of Theoretical Biology, 37 , 1–52.

Nowak, M. A. (2006). Five rules for the evolution of cooperation. Science, 314 , 1560–1563.

Nowak, M. A., Tarnita, C. R., & Wilson, E. O. (2010). The evolution of eusociality. Nature, 466 , 1057–1062.

Rebers, S., & Koopmans, R. (2012). Altruistic punishment and between-group competition. Human Nature, 23 , 173–190.

Reid, C. R., Lutz, M. J., Powell, S., Kao, A. B., Couzin, I. D., & Garnier, S. (2015). Army ants dynamically adjust living bridges in response to a cost-benefit trade-off. Proceedings of the National Academy of Sciences, 112 , 15113–15118.

Seeley, T. D. (1997). Honey bee colonies are group-level adaptive units. The American Naturalist, 150 , S22–S41.

Trivers, R. L. (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46 , 35–57.

Download references

Author information

Authors and affiliations.

University of South Carolina Beaufort, Bluffton, SC, USA

Carey Fitzgerald

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Carey Fitzgerald .

Editor information

Editors and affiliations.

Department of Psychology, Oakland University, Rochester, Michigan, USA

Todd K. Shackelford

Rochester, Michigan, USA

Viviana A. Weekes-Shackelford

Section Editor information

Pennsylvania State University, University Park, PA, USA

Karin Machluf

Rights and permissions

Reprints and permissions

Copyright information

© 2018 Springer International Publishing AG, part of Springer Nature

About this entry

Cite this entry.

Fitzgerald, C. (2018). Examples of Group Selection. In: Shackelford, T., Weekes-Shackelford, V. (eds) Encyclopedia of Evolutionary Psychological Science. Springer, Cham. https://doi.org/10.1007/978-3-319-16999-6_2126-1

Download citation

DOI : https://doi.org/10.1007/978-3-319-16999-6_2126-1

Received : 04 May 2016

Accepted : 04 June 2018

Published : 12 June 2018

Publisher Name : Springer, Cham

Print ISBN : 978-3-319-16999-6

Online ISBN : 978-3-319-16999-6

eBook Packages : Springer Reference Behavioral Science and Psychology Reference Module Humanities and Social Sciences Reference Module Business, Economics and Social Sciences

• Publish with us

Policies and ethics

• Find a journal
• Track your research

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• Proc Natl Acad Sci U S A
• v.72(1); 1975 Jan

A theory of group selection.

In organisms possessing a dispersal phase the processes of mating, competition, feeding, and predation are often carried out within "trait-groups," defined as populations enclosed in areas smaller than the boundaries of the deme. A simple model shows that this can lead to the selection of "altruistic" traits that favor the fitness of the group over that of the individual. The extent of group selection that occurs depends mainly on the variation in the composition of genotypes between trait-groups. The traditional concepts of group and individual selection are seen as two extremes of a continuum, with systems in nature operating over the interval in between.

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (604K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References .

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

• Boorman SA, Levitt PR. Group selection on the boundary of a stable population. Theor Popul Biol. 1973 Mar; 4 (1):85–128. [ PubMed ] [ Google Scholar ]