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Sunday, May 18, 2025

Steven Pinker

From Wikipedia, the free encyclopedia
Steven Pinker
Pinker in 2023
Born
Steven Arthur Pinker

September 18, 1954 (age 70)
Montreal, Quebec, Canada
Nationality
  • Canadian
  • American
Education
Notable work
Spouses

(m. 1980; div. 1992)

Ilavenil Subbiah
(m. 1995; div. 2006)

(m. 2007)
RelativesSusan Pinker (sister)

Awards
Scientific career
Fields
Institutions
ThesisThe representation and manipulation of three-dimensional space in mental images (1979)
Doctoral advisorStephen Kosslyn
Websitestevenpinker.com

Steven Arthur Pinker (born September 18, 1954) is a Canadian-American cognitive psychologist, psycholinguist, popular science author, and public intellectual. He is an advocate of evolutionary psychology and the computational theory of mind.

Pinker is the Johnstone Family Professor of Psychology at Harvard University. He specializes in visual cognition and developmental linguistics, and his experimental topics include mental imagery, shape recognition, visual attention, regularity and irregularity in language, the neural basis of words and grammar, and childhood language development. Other experimental topics he works on are the psychology of cooperation and of communication, including emotional expression, euphemism, innuendo, and how people use "common knowledge", a term of art meaning the shared understanding in which two or more people know something, know that the other one knows, know the other one knows that they know, and so on.

Pinker has written two technical books that proposed a general theory of language acquisition and applied it to children's learning of verbs. In particular, his work with Alan Prince published in 1989 critiqued the connectionist model of how children acquire the past tense of English verbs, positing that children use default rules, such as adding -ed to make regular forms, sometimes in error, but are obliged to learn irregular forms one by one.

Pinker is the author of nine books for general audiences. The Language Instinct (1994), How the Mind Works (1997), Words and Rules (2000), The Blank Slate (2002), and The Stuff of Thought (2007) describe aspects of psycholinguistics and cognitive science, and include accounts of his own research, positing that language is an innate behavior shaped by natural selection and adapted to our communication needs. Pinker's The Sense of Style (2014) is a general language-oriented style guide. Pinker's book The Better Angels of Our Nature (2010) posits that violence in human societies has generally declined over time, and identifies six major trends and five historical forces of this decline, the most important being the humanitarian revolution brought by the Enlightenment and its associated cultivation of reason. Enlightenment Now (2018) further argues that the human condition has generally improved over recent history because of reason, science, and humanism. The nature and importance of reason is also discussed in his next book Rationality: What It Is, Why It Seems Scarce, Why It Matters (2021).

In 2004, Pinker was named in Time's "The 100 Most Influential People in the World Today", and in the years 2005, 2008, 2010, and 2011 in Foreign Policy's list of "Top 100 Global Thinkers". Pinker was also included in Prospect Magazine's top 10 "World Thinkers" in 2013. He has won awards from the American Psychological Association, the National Academy of Sciences, the Royal Institution, the Cognitive Neuroscience Society, and the American Humanist Association. He delivered the Gifford Lectures at the University of Edinburgh in 2013. He has served on the editorial boards of a variety of journals, and on the advisory boards of several institutions. Pinker was the chair of the Usage Panel of the American Heritage Dictionary from 2008 to 2018.

Biography

Pinker was born in Montreal, Quebec, in 1954, to a middle-class secular Jewish family in an English-speaking community. His grandparents immigrated to Canada from Poland and Romania in 1926, and owned a small necktie factory in Montreal. His father, Harry, worked in real estate and was a lawyer. His mother, Roslyn, was originally a homemaker, but later became a guidance counsellor and a high-school vice-principal. In an interview, Pinker described his mother as "very intellectual" and "an intense reader [who] knows everything". His brother, Robert, worked for the Canadian government for several decades as an administrator and a policy analyst, while his sister, Susan Pinker, is a psychologist and writer who authored The Sexual Paradox and The Village Effect. Susan is also a columnist for The Wall Street Journal.

Pinker graduated from Dawson College in 1973. He graduated from McGill University in 1976 with a Bachelor of Arts in psychology, then did doctoral studies in experimental psychology at Harvard University under Stephen Kosslyn, receiving a PhD in 1979. He did research at the Massachusetts Institute of Technology (MIT) for a year, then became a professor at Harvard and later, Stanford University.

From 1982 until 2003 Pinker taught at the Department of Brain and Cognitive Sciences at MIT, was the co-director of the Center for Cognitive Science (1985–1994), and eventually became the director of the Center for Cognitive Neuroscience (1994–1999), taking a one-year sabbatical at the University of California, Santa Barbara, in 1995–96. Since 2003 he has served as the Johnstone Family Professor of Psychology at Harvard, and between 2008 and 2013 he also held the title of Harvard College Professor in recognition of his dedication to teaching. In the early 2010s, he gave lectures as a visiting professor at the New College of the Humanities, a private college in London.

Pinker married Nancy Etcoff in 1980 and they divorced in 1992; he married again in 1995 and again divorced. His third wife, whom he married in 2007, is the novelist and philosopher Rebecca Goldstein. He has two stepdaughters, the novelist Yael Goldstein Love and the poet Danielle Blau. Pinker adopted atheism at 13, but at various times was a "cultural Jew". Pinker is an avid cyclist.

Linguistic career

Pinker in 2011

Pinker's research on visual cognition, begun in collaboration with his thesis adviser, Stephen Kosslyn, showed that mental images represent scenes and objects as they appear from a specific vantage point (rather than capturing their intrinsic three-dimensional structure), and thus correspond to the neuroscientist David Marr's theory of a "two-and-a-half-dimensional sketch." He also showed that this level of representation is used in visual attention, and in object recognition (at least for asymmetrical shapes), contrary to Marr's theory that recognition uses viewpoint-independent representations.

In psycholinguistics, Pinker became known early in his career for promoting computational learning theory as a way to understand language acquisition in children. He wrote a tutorial review of the field followed by two books that advanced his own theory of language acquisition, and a series of experiments on how children acquire the passive, dative, and locative constructions. These books were Language Learnability and Language Development (1984), in Pinker's words "outlin[ing] a theory of how children acquire the words and grammatical structures of their mother tongue", and Learnability and Cognition: The Acquisition of Argument Structure (1989), in Pinker's words "focus[ing] on one aspect of this process, the ability to use different kinds of verbs in appropriate sentences, such as intransitive verbs, transitive verbs, and verbs taking different combinations of complements and indirect objects". He then focused on verbs of two kinds that illustrate what he considers to be the processes required for human language: retrieving whole words from memory, like the past form of the irregular verb "bring", namely "brought"; and using rules to combine (parts of) words, like the past form of the regular verb "walk", namely "walked".

In 1988 Pinker and Alan Prince published a critique of a connectionist model of the acquisition of the past tense (a textbook problem in language acquisition), followed by a series of studies of how people use and acquire the past tense. This included a monograph on children's regularization of irregular forms and his popular 1999 book, Words and Rules: The Ingredients of Language. Pinker argued that language depends on two things: the associative remembering of sounds and their meanings in words, and the use of rules to manipulate symbols for grammar. He presented evidence against connectionism, where a child would have to learn all forms of all words and would simply retrieve each needed form from memory, in favour of the older alternative theory, the use of words and rules combined by generative phonology. He showed that mistakes made by children indicate the use of default rules to add suffixes such as "-ed": for instance 'breaked' and 'comed' for 'broke' and 'came'. He argued that this shows that irregular verb-forms in English have to be learnt and retrieved from memory individually, and that the children making these errors were predicting the regular "-ed" ending in an open-ended way by applying a mental rule. This rule for combining verb stems and the usual suffix can be expressed as Vpast → Vstem + d, where V is a verb and d is the regular ending. Pinker further argued that since the ten most frequently occurring English verbs (be, have, do, say, make ... ) are all irregular, while 98.2% of the thousand least common verbs are regular, there is a "massive correlation" of frequency and irregularity. He explains this by arguing that every irregular form, such as 'took', 'came' and 'got', has to be committed to memory by the children in each generation, or else lost, and that the common forms are the most easily memorized. Any irregular verb that falls in popularity past a certain point is lost, and all future generations will treat it as a regular verb instead.

In 1990 Pinker, with Paul Bloom, published a paper arguing that the human language faculty must have evolved through natural selection. The article provided arguments for a continuity-based view of language evolution, contrary to then-current discontinuity-based theories that see language as suddenly appearing with the advent of Homo sapiens as a kind of evolutionary accident. This discontinuity-based view was prominently argued by two main authorities, linguist Noam Chomsky and Stephen Jay Gould. The paper became widely cited and created renewed interest in the evolutionary prehistory of language, and has been credited with shifting the central question of the debate from "did language evolve?" to "how did language evolve?" The article also presaged Pinker's argument in The Language Instinct.

In 2006 Pinker provided to Alan Dershowitz, a personal friend of Pinker's who was Jeffrey Epstein's defense attorney, Pinker's own interpretation of the wording of a federal law pertaining to the enticement of minors into illegal sex acts via the internet. Dershowitz included Pinker's opinion in a letter to the court during proceedings that resulted in a plea deal in which all federal sex trafficking charges against Epstein were dropped. In 2019, Pinker stated that he was unaware of the nature of the charges against Epstein, and that he engaged in an unpaid favor for his Harvard colleague Dershowitz, as he had regularly done. He stated in an interview with BuzzFeed News that he regrets writing the letter. Pinker says he never received money from Epstein and met with him three times over more than a dozen years, and said he could never stand Epstein and tried to keep his distance.

Popularization of science

Human cognition and natural language

Pinker at CSICon in 2018, hosted by the Committee for Skeptical Inquiry

Pinker's 1994 The Language Instinct was the first of several books to combine cognitive science with behavioral genetics and evolutionary psychology. It introduces the science of language and popularizes Noam Chomsky's theory that language is an innate faculty of mind, with the controversial twist that the faculty for language evolved by natural selection as an adaptation for communication. Pinker criticizes several widely held ideas about language – that it needs to be taught, that people's grammar is poor and getting worse with new ways of speaking, the Sapir–Whorf hypothesis that language limits the kinds of thoughts a person can have, and that other great apes can learn languages. Pinker sees language as unique to humans, evolved to solve the specific problem of communication among social hunter-gatherers. He argues that it is as much an instinct as specialized adaptative behavior in other species, such as a spider's web-weaving or a beaver's dam-building.

Pinker states in his introduction that his ideas are "deeply influenced" by Chomsky; he also lists scientists whom Chomsky influenced to "open up whole new areas of language study, from child development and speech perception to neurology and genetics" – Eric Lenneberg, George Miller, Roger Brown, Morris Halle and Alvin Liberman. Brown mentored Pinker through his thesis; Pinker stated that Brown's "funny and instructive" book Words and Things (1958) was one of the inspirations for The Language Instinct.

There has been debate about the explanatory adequacy of the theory. By 2015, the linguistic nativist views of Pinker and Chomsky had a number of challenges on the grounds that they had incorrect core assumptions and were inconsistent with research evidence from psycholinguistics and child language acquisition. The reality of Pinker's proposed language instinct, and the related claim that grammar is innate and genetically based, has been contested by linguists such as Geoffrey Sampson in his 1997 book, Educating Eve: The 'Language Instinct' Debate. Sampson argues that "while it may seem attractive to argue the nature side of the 'nature versus nurture' debate, the nurture side may better support the creativity and nobility of the human mind." Sampson denies there is a language instinct, and argues that children can learn language because people can learn anything. Others have sought a middle ground between Pinker's nativism and Sampson's culturalism.

The assumptions underlying the nativist view have also been questioned in Jeffrey Elman's Rethinking Innateness: A Connectionist Perspective on Development, which defends the connectionist approach that Pinker attacked. In his 1996 book Impossible Minds, the machine intelligence researcher Igor Aleksander calls The Language Instinct excellent, and argues that Pinker presents a relatively soft claim for innatism, accompanied by a strong dislike of the 'Standard Social Sciences Model' or SSSM (Pinker's term), which supposes that development is purely dependent on culture. Further, Aleksander writes that while Pinker criticises some attempts to explain language processing with neural nets, Pinker later makes use of a neural net to create past tense verb forms correctly. Aleksander concludes that while he doesn't support the SSSM, "a cultural repository of language just seems the easy trick for an efficient evolutionary system armed with an iconic state machine to play."

Pinker lecturing to humanists in the United Kingdom (2018)

Two other books, How the Mind Works (1997) and The Blank Slate (2002), broadly surveyed the mind and defended the idea of a complex human nature with many mental faculties that are genetically adaptive (Pinker is an ally of Daniel Dennett and Richard Dawkins in many disputes surrounding adaptationism). Another major theme in Pinker's theories is that human cognition works, in part, by combinatorial symbol-manipulation, not just associations among sensory features, as in many connectionist models. On the debate around The Blank Slate, Pinker called Thomas Sowell's book A Conflict of Visions "wonderful", and explained that "The Tragic Vision" and the "Utopian Vision" are the views of human nature behind right- and left-wing ideologies.

In Words and Rules: the Ingredients of Language (1999), Pinker argues from his own research that regular and irregular phenomena are products of computation and memory lookup, respectively, and that language can be understood as an interaction between the two. "Words and Rules" is also the title of an essay by Pinker outlining many of the topics discussed in the book. Critiqueing the book from the perspective of generative linguistics Charles Yang, in the London Review of Books, writes that "this book never runs low on hubris or hyperbole". The book's topic, the English past tense, is in Yang's view unglamorous, and Pinker's attempts at compromise risk being in no man's land between rival theories. Giving the example of German, Yang argues that irregular nouns in that language at least all belong to classes, governed by rules, and that things get even worse in languages that attach prefixes and suffixes to make up long 'words': they can't be learnt individually, as there are untold numbers of combinations. "All Pinker (and the connectionists) are doing is turning over the rocks at the base of the intellectual landslide caused by the Chomskian revolution."

In The Stuff of Thought (2007), Pinker looks at a wide range of issues around the way words related to thoughts on the one hand, and to the world outside ourselves on the other. Given his evolutionary perspective, a central question is how an intelligent mind capable of abstract thought evolved: how a mind adapted to Stone Age life could work in the modern world. Many quirks of language are the result.

Pinker is critical of theories about the evolutionary origins of language that argue that linguistic cognition might have evolved from earlier musical cognition. He sees language as being tied primarily to the capacity for logical reasoning, and speculates that human proclivity for music may be a spandrel – a feature not adaptive in its own right, but that has persisted through other traits that are more broadly practical, and thus selected for. In How the Mind Works, Pinker reiterates Immanuel Kant's view that music is not in itself an important cognitive phenomenon, but that it happens to stimulate important auditory and spatio-motor cognitive functions. Pinker compares music to "auditory cheesecake", stating that "As far as biological cause and effect is concerned, music is useless". This argument has been rejected by Daniel Levitin and Joseph Carroll, experts in music cognition, who argue that music has had an important role in the evolution of human cognition. In his book This Is Your Brain On Music, Levitin argues that music could provide adaptive advantage through sexual selection, social bonding, and cognitive development; he questions the assumption that music is the antecedent to language, as opposed to its progenitor, noting that many species display music-like habits that could be seen as precursors to human music.

Pinker has also been critical of "whole language" reading instruction techniques, stating in How the Mind Works, "... the dominant technique, called 'whole language,' the insight that [spoken] language is a naturally developing human instinct has been garbled into the evolutionarily improbable claim that reading is a naturally developing human instinct." In the appendix to the 2007 reprinted edition of The Language Instinct, Pinker cited Why Our Children Can't Read by cognitive psychologist Diane McGuinness as his favorite book on the subject and noted:

One raging public debate involving language went unmentioned in The Language Instinct: the "reading wars," or dispute over whether children should be explicitly taught to read by decoding the sounds of words from their spelling (loosely known as "phonics") or whether they can develop it instinctively by being immersed in a text-rich environment (often called "whole language"). I tipped my hand in the paragraph in [the sixth chapter of the book] which said that language is an instinct but reading is not. Like most psycholinguists (but apparently unlike many school boards), I think it's essential for children to be taught to become aware of speech sounds and how they are coded in strings of letters.

The Better Angels of Our Nature

Detail from "Mars" in Das Mittelalterliche Hausbuch, c. 1475 – 1480. Pinker used the image in The Better Angels of Our Nature to illustrate violence in the Middle Ages.

In The Better Angels of Our Nature, published in 2011, Pinker argues that violence, including tribal warfare, homicide, cruel punishments, child abuse, animal cruelty, domestic violence, lynching, pogroms, and international and civil wars, has decreased over multiple scales of time and magnitude. Pinker considers it unlikely that human nature has changed. In his view, it is more likely that human nature comprises inclinations toward violence and those that counteract them, the "better angels of our nature". He outlines several "major historical declines of violence" that all have their own social/cultural/economic causes.

Response to the book was divided. Many critics found its arguments convincing and its synthesis of a large volume of historical evidence compelling. This and other aspects drew criticism, including the use of deaths per capita as a metric, Pinker's liberal humanism, the focus on Europe, the interpretation of historical data, and its image of indigenous people. Archaeologist David Wengrow summarized Pinker's approach to archaeological science as "a modern psychologist making it up as he goes along".

English writing style in the 21st century

In his seventh popular book, The Sense of Style: The Thinking Person's Guide to Writing in the 21st Century (2014), Pinker attempts to provide a writing style guide that is informed by modern science and psychology, given that William Strunk wrote The Elements of Style in 1918, nearly a full century prior to Pinker’s publication.

Views

Pinker and Nils Brose speaking at a neuroscience conference

Pinker identifies as a liberal who is critical of some aspects of the political left. He supports same-sex marriage, a universal basic income, the legalization of drugs, the taxation of carbon, and the abolition of capital punishment. Pinker is a strong supporter of the Democratic Party. However, Pinker has argued that the far-left has created an atmosphere of intellectual intolerance on college campuses and elsewhere, and helped form the Council on Academic Freedom at Harvard to combat what he described as an epidemic of censorship at universities. He was a signatory of the Letter on Justice and Open Debate which argued that discussion of political issues was being silenced by a widespread "intolerance of opposing views, a vogue for public shaming and ostracism, and a tendency to dissolve complex issues into a binding moral certainty."

Pinker has sharply criticized social conservatives, such as former chairman of the President's Council on Bioethics Leon Kass, for opposing stem cell research, arguing that their moral views were mere expressions of disgust that were obstructing treatments that could save millions of lives.

Pinker is a frequent participant in public debates surrounding the contributions of science to contemporary society. Social commentators such as Ed West, author of The Diversity Illusion, consider Pinker important and daring in his willingness to confront taboos, as in The Blank Slate. According to West, the doctrine of tabula rasa remained accepted "as fact, rather than fantasy" a decade after the book's publication. West describes Pinker as "no polemicist, and he leaves readers to draw their own conclusions".

In January 2005 Pinker defended comments by then-President of Harvard University Lawrence Summers. Summers had speculated that in addition to differing societal demands and discrimination, "different availability of aptitude at the high end" may contribute to gender gaps in mathematics and science. In a debate between Pinker and Elizabeth Spelke on gender and science, Pinker argued in favor of the proposition that the gender difference in representation in elite universities was "explainable by some combination of biological differences in average temperaments and talents interacting with socialization and bias".

In January 2009 Pinker wrote an article about the Personal Genome Project and its possible impact on the understanding of human nature in The New York Times. He discussed the new developments in epigenetics and gene-environment interactions in the afterword to the 2016 edition of his book The Blank Slate. Pinker has been criticised for using the data of scientific racists (on subjects unrelated to race), such as the blogger Steven Sailer, with journalist Angela Saini stating that "for many people, Pinker's willingness to entertain the work of individuals who are on the far right and white supremacists has gone beyond the pale". Pinker has stated that he condemns racism.

In a November 2009 article for The New York Times, Pinker wrote a mixed review of Malcolm Gladwell's essays, criticizing his analytical methods. Gladwell replied, disputing Pinker's comments about the importance of IQ on teaching performance and by analogy the effect, if any, of draft order on quarterback performance in the National Football League. Advanced NFL Stats addressed the issue statistically, siding with Pinker and showing that differences in methodology could explain the two men's differing opinions.

In an appearance for BBC World Service's Exchanges At The Frontier programme, an audience member questioned whether the virtuous developments in culture and human nature (documented in The Better Angels of Our Nature) could have expressed in our biology either through genetic or epigenetic expression. Pinker responded that it was unlikely since "some of the declines have occurred far too rapidly for them to be explicable by biological evolution, which has a speed limit measured in generations, but crime can plummet in a span of 15 years and some of these humanitarian reforms like eliminating slavery and torture occurred in, say, 50 years". Helga Vierich and Cathryn Townsend wrote a critical review of Pinker's sweeping "civilizational" explanations for patterns of human violence and warfare in response to a lecture he gave at Cambridge University in September 2015.

In his 2018 book Enlightenment Now, Pinker posited that Enlightenment rationality should be defended against attacks from both the political left and political right. In a debate with Pinker, post-colonial theorist Homi Bhabha said that Enlightenment philosophy had immoral consequences such as inequality, slavery, imperialism, world wars, and genocide, and that Pinker downplayed them. Pinker argued that Bhabha had perceived the causal relationship between Enlightenment thinking and these sources of suffering "backwards", responding in part that "The natural state of humanity, at least since the dawn of civilization, is poverty, disease, ignorance, exploitation, and violence (including slavery and imperial conquest). It is knowledge, mobilised to improve human welfare, that allows anyone to rise above this state." In a 2019 story in Current Affairs, proprietor Nathan Robinson criticised Pinker, saying that he misrepresents his critics' arguments against his work.

In 2020, an open letter to the Linguistic Society of America requesting the removal of Pinker from its list of LSA Fellows and its list of media experts was signed by hundreds of academics. The letter accused Pinker of a "pattern of drowning out the voices of people suffering from racist and sexist violence, in particular in the immediate aftermath of violent acts and/or protests against the systems that created them", citing as examples six of Pinker's tweets. Pinker said in reply that through this letter, he, and more importantly, younger academics with less protection, were being threatened by "a regime of intimidation that constricts the theatre of ideas." Several academics criticized the letter and expressed support for Pinker. The executive committee of the Linguistic Society of America declined to strike Pinker from its lists and issued a response letter stating that "It is not the mission of the Society to control the opinions of its members, nor their expression."

In December 2024, Pinker resigned from the board of honorary members of the Freedom from Religion Foundation over what he and several colleagues viewed as the Foundation's "quasi-religious" approach to defining gender. His resignation was followed by those of Jerry Coyne and Richard Dawkins.

Awards and distinctions

Pinker was named one of Time's 100 most influential people in the world in 2004 and one of Prospect and Foreign Policy's 100 top public intellectuals in both years the poll was carried out, 2005 and 2008; in 2010 and 2011 he was named by Foreign Policy to its list of top global thinkers. In 2016, he was elected to the National Academy of Sciences.

His research in cognitive psychology has won the Early Career Award (1984) and Boyd McCandless Award (1986) from the American Psychological Association, the Troland Research Award (1993) from the National Academy of Sciences, the Henry Dale Prize (2004) from the Royal Institution of Great Britain, and the George Miller Prize (2010) from the Cognitive Neuroscience Society. He has also received honorary doctorates from the universities of Newcastle, Surrey, Tel Aviv, McGill, Simon Fraser University and the University of Tromsø. He was twice a finalist for the Pulitzer Prize, in 1998 and in 2003. Pinker received the Golden Plate Award of the American Academy of Achievement in 1999. On May 13, 2006, he received the American Humanist Association's Humanist of the Year award for his contributions to public understanding of human evolution. For 2022 he was awarded the BBVA Foundation Frontiers of Knowledge Award in the category of "Humanities and Social Sciences".

From 2008 to 2018, Pinker chaired the Usage Panel of the American Heritage Dictionary. He wrote the essay on usage for the fifth edition of the Dictionary, published in 2011. In February 2001, Pinker, "whose hair has long been the object of admiration, and envy, and intense study",[122] was nominated by acclamation as the first member of the Luxuriant Flowing Hair Club for Scientists (LFHCfS) organized by the Annals of Improbable Research.

Group selection

From Wikipedia, the free encyclopedia
image of lekking blackcock, an instance of social behaviour
Early explanations of social behaviour, such as the lekking of blackcock, spoke of "the good of the species". Blackcocks at the Lek watercolour and bodycolour by Archibald Thorburn, 1901.

Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the level of the individual or gene.

Early authors such as V. C. Wynne-Edwards and Konrad Lorenz argued that the behavior of animals could affect their survival and reproduction as groups, speaking for instance of actions for the good of the species. In the 1930s, Ronald Fisher and J. B. S. Haldane proposed the concept of kin selection, a form of biological altruism from the gene-centered view of evolution, arguing that animals should sacrifice for their relatives, and thereby implying that they should not sacrifice for non-relatives. From the mid-1960s, evolutionary biologists such as John Maynard Smith, W. D. Hamilton, George C. Williams, and Richard Dawkins argued that natural selection acted primarily at the level of the gene. They argued on the basis of mathematical models that individuals would not altruistically sacrifice fitness for the sake of a group unless it would ultimately increase the likelihood of an individual passing on their genes. A consensus emerged that group selection did not occur, including in special situations such as the haplodiploid social insects like honeybees (in the Hymenoptera), where kin selection explains the behaviour of non-reproductives equally well, since the only way for them to reproduce their genes is via kin.

In 1994 David Sloan Wilson and Elliott Sober argued for multi-level selection, including group selection, on the grounds that groups, like individuals, could compete. In 2010 three authors including E. O. Wilson, known for his work on social insects especially ants, again revisited the arguments for group selection. They argued that group selection can occur when competition between two or more groups, some containing altruistic individuals who act cooperatively together, is more important for survival than competition between individuals within each group. A large group of ethologists conceded that while inclusive fitness may be debatable, it was still a useful theory in practice. However, the vast majority of behavioural biologists have not been convinced by renewed attempts to revisit group selection as a plausible mechanism of evolution.

Early developments

Charles Darwin developed the theory of evolution in his book, Origin of Species. Darwin also made the first suggestion of group selection in The Descent of Man that the evolution of groups could affect the survival of individuals. He wrote, "If one man in a tribe... invented a new snare or weapon, the tribe would increase in number, spread, and supplant other tribes. In a tribe thus rendered more numerous there would always be a rather better chance of the birth of other superior and inventive members."

Once Darwinism had been accepted in the modern synthesis of the mid-twentieth century, animal behavior was glibly explained with unsubstantiated hypotheses about survival value, which was largely taken for granted. The naturalist Konrad Lorenz had argued loosely in books like On Aggression (1966) that animal behavior patterns were "for the good of the species", without actually studying survival value in the field. Richard Dawkins noted that Lorenz was a "'good of the species' man" so accustomed to group selection thinking that he did not realize his views "contravened orthodox Darwinian theory". The ethologist Niko Tinbergen praised Lorenz for his interest in the survival value of behavior, and naturalists enjoyed Lorenz's writings for the same reason. In 1962, group selection was used as a popular explanation for adaptation by the zoologist V. C. Wynne-Edwards. In 1976, Richard Dawkins wrote a well-known book on the importance of evolution at the level of the gene or the individual, The Selfish Gene.

Honeybee social behaviour can be explained by their inheritance system
Social behavior in honeybees is explained by kin selection: their haplodiploid inheritance system makes workers very closely related to their queen (centre).

From the mid-1960s, evolutionary biologists argued that natural selection acted primarily at the level of the individual. In 1964, John Maynard Smith, C. M. Perrins (1964), and George C. Williams in his 1966 book Adaptation and Natural Selection cast serious doubt on group selection as a major mechanism of evolution; Williams's 1971 book Group Selection assembled writings from many authors on the same theme.

It was at that time generally agreed that this was the case even for eusocial insects such as honeybees, which encourages kin selection, since workers are closely related.

Kin selection and inclusive fitness theory

Experiments from the late 1970s suggested that selection involving groups was possible. Early group selection models assumed that genes acted independently, for example a gene that coded for cooperation or altruism. Genetically based reproduction of individuals implies that, in group formation, the altruistic genes would need a way to act for the benefit of members in the group to enhance the fitness of many individuals with the same gene. But it is expected from this model that individuals of the same species would compete against each other for the same resources. This would put cooperating individuals at a disadvantage, making genes for cooperation likely to be eliminated. Group selection on the level of the species is flawed because it is difficult to see how selective pressures would be applied to competing/non-cooperating individuals.

Kin selection between related individuals is accepted as an explanation of altruistic behavior. R.A. Fisher in 1930 and J.B.S. Haldane in 1932 set out the mathematics of kin selection, with Haldane famously joking that he would willingly die for two brothers or eight cousins. In this model, genetically related individuals cooperate because survival advantages to one individual also benefit kin who share some fraction of the same genes, giving a mechanism for favoring genetic selection.

Inclusive fitness theory, first proposed by W. D. Hamilton in the early 1960s, gives a selection criterion for evolution of social traits when social behavior is costly to an individual organism's survival and reproduction. The criterion is that the reproductive benefit to relatives who carry the social trait, multiplied by their relatedness (the probability that they share the altruistic trait) exceeds the cost to the individual. Inclusive fitness theory is a general treatment of the statistical probabilities of social traits accruing to any other organisms likely to propagate a copy of the same social trait. Kin selection theory treats the narrower but simpler case of the benefits to close genetic relatives (or what biologists call 'kin') who may also carry and propagate the trait. A significant group of biologists support inclusive fitness as the explanation for social behavior in a wide range of species, as supported by experimental data. An article was published in Nature with over a hundred coauthors.

One of the questions about kin selection is the requirement that individuals must know if other individuals are related to them, or kin recognition. Any altruistic act has to preserve similar genes. One argument given by Hamilton is that many individuals operate in "viscous" conditions, so that they live in physical proximity to relatives. Under these conditions, they can act altruistically to any other individual, and it is likely that the other individual will be related. This population structure builds a continuum between individual selection, kin selection, kin group selection and group selection without a clear boundary for each level. However, early theoretical models by D.S. Wilson et al. and Taylor showed that pure population viscosity cannot lead to cooperation and altruism. This is because any benefit generated by kin cooperation is exactly cancelled out by kin competition; additional offspring from cooperation are eliminated by local competition. Mitteldorf and D. S. Wilson later showed that if the population is allowed to fluctuate, then local populations can temporarily store the benefit of local cooperation and promote the evolution of cooperation and altruism. By assuming individual differences in adaptations, Yang further showed that the benefit of local altruism can be stored in the form of offspring quality and thus promote the evolution of altruism even if the population does not fluctuate. This is because local competition among more individuals resulting from local altruism increases the average local fitness of the individuals that survive.

Another explanation for the recognition of genes for altruism is that a single trait, group reciprocal kindness, is capable of explaining the vast majority of altruism that is generally accepted as "good" by modern societies. The phenotype of altruism relies on recognition of the altruistic behavior by itself. The trait of kindness will be recognized by sufficiently intelligent and undeceived organisms in other individuals with the same trait. Moreover, the existence of such a trait predicts a tendency for kindness to unrelated organisms that are apparently kind, even if the organisms are of another species. The gene need not be exactly the same, so long as the effect or phenotype is similar. Multiple versions of the gene—or even meme—would have virtually the same effect. This explanation was given by Richard Dawkins as an analogy of a man with a green beard. Green-bearded men are imagined as tending to cooperate with each other simply by seeing a green beard, where the green beard trait is incidentally linked to the reciprocal kindness trait.

Multilevel selection theory

Kin selection or inclusive fitness is accepted as an explanation for cooperative behavior in many species, but the scientist David Sloan Wilson argues that human behavior is difficult to explain with only this approach. In particular, he claims it does not seem to explain the rapid rise of human civilization. Wilson has argued that other factors must also be considered in evolution. Wilson and others have continued to develop group selection models.

Early group selection models were flawed because they assumed that genes acted independently; but genetically based interactions among individuals are ubiquitous in group formation because genes must cooperate for the benefit of association in groups to enhance the fitness of group members. Additionally, group selection on the level of the species is flawed because it is difficult to see how selective pressures would be applied; selection in social species of groups against other groups, rather than the species entire, seems to be the level at which selective pressures are plausible. On the other hand, kin selection is accepted as an explanation of altruistic behavior. Some biologists argue that kin selection and multilevel selection are both needed to "obtain a complete understanding of the evolution of a social behavior system".

In 1994, David Sloan Wilson and Elliott Sober argued that the case against group selection had been overstated. They considered whether groups can have functional organization in the same way as individuals, and consequently whether groups can be "vehicles" for selection. They do not posit evolution on the level of the species, but selective pressures that winnow out small groups within a species, e.g. groups of social insects or primates. Groups that cooperate better might survive and reproduce more than those that did not. Resurrected in this way, Wilson & Sober's new group selection is called multilevel selection theory.

In 2010, Martin Nowak, C. E. Tarnita and E. O. Wilson argued for multi-level selection, including group selection, to correct what they saw as deficits in the explanatory power of inclusive fitness. A response from 137 other evolutionary biologists argued "that their arguments are based upon a misunderstanding of evolutionary theory and a misrepresentation of the empirical literature".

David Sloan Wilson compared multilevel selection to a nested set of Russian dolls
David Sloan Wilson and Elliott Sober's 1994 Multilevel Selection Model, illustrated by a nested set of Russian matryoshka dolls. Wilson himself compared his model to such a set.

Wilson compared the layers of competition and evolution to nested sets of Russian matryoshka dolls. The lowest level is the genes, next come the cells, then the organism level and finally the groups. The different levels function cohesively to maximize fitness, or reproductive success. The theory asserts that selection for the group level, involving competition between groups, must outweigh the individual level, involving individuals competing within a group, for a group-benefiting trait to spread.

Multilevel selection theory focuses on the phenotype because it looks at the levels that selection directly acts upon. For humans, social norms can be argued to reduce individual level variation and competition, thus shifting selection to the group level. The assumption is that variation between different groups is larger than variation within groups. Competition and selection can operate at all levels regardless of scale. Wilson wrote, "At all scales, there must be mechanisms that coordinate the right kinds of action and prevent disruptive forms of self-serving behavior at lower levels of social organization." E. O. Wilson summarized, "In a group, selfish individuals beat altruistic individuals. But, groups of altruistic individuals beat groups of selfish individuals."

Wilson ties the multilevel selection theory regarding humans to another theory, gene–culture coevolution, by acknowledging that culture seems to characterize a group-level mechanism for human groups to adapt to environmental changes.

MLS theory can be used to evaluate the balance between group selection and individual selection in specific cases. An experiment by William Muir compared egg productivity in hens, showing that a hyper-aggressive strain had been produced through individual selection, leading to many fatal attacks after only six generations; by implication, it could be argued that group selection must have been acting to prevent this in real life. Group selection has most often been postulated in humans and, notably, eusocial Hymenoptera that make cooperation a driving force of their adaptations over time and have a unique system of inheritance involving haplodiploidy that allows the colony to function as an individual while only the queen reproduces.

Wilson and Sober's work revived interest in multilevel selection. In a 2005 article, E. O. Wilson argued that kin selection could no longer be thought of as underlying the evolution of extreme sociality, for two reasons. First, he suggested, the argument that haplodiploid inheritance (as in the Hymenoptera) creates a strong selection pressure towards nonreproductive castes is mathematically flawed. Second, eusociality no longer seems to be confined to the hymenopterans; increasing numbers of highly social taxa have been found in the years since Wilson's foundational text Sociobiology: A New Synthesis was published in 1975. These including a variety of insect species, as well as two rodent species (the naked mole-rat and the Damaraland mole rat). Wilson suggests the equation for Hamilton's rule:

rb > c

(where b represents the benefit to the recipient of altruism, c the cost to the altruist, and r their degree of relatedness) should be replaced by the more general equation

rbk + be > c

in which bk is the benefit to kin (b in the original equation) and be is the benefit accruing to the group as a whole. He then argues that, in the present state of the evidence in relation to social insects, it appears that be>rbk, so that altruism needs to be explained in terms of selection at the colony level rather than at the kin level. However, kin selection and group selection are not distinct processes, and the effects of multi-level selection are already accounted for in Hamilton's rule, rb>c, provided that an expanded definition of r, not requiring Hamilton's original assumption of direct genealogical relatedness, is used, as proposed by E. O. Wilson himself.

Spatial populations of predators and prey show restraint of reproduction at equilibrium, both individually and through social communication, as originally proposed by Wynne-Edwards. While these spatial populations do not have well-defined groups for group selection, the local spatial interactions of organisms in transient groups are sufficient to lead to a kind of multi-level selection. There is however as yet no evidence that these processes operate in the situations where Wynne-Edwards posited them.

Rauch et al.'s analysis of host-parasite evolution is broadly hostile to group selection. Specifically, the parasites do not individually moderate their transmission; rather, more transmissible variants – which have a short-term but unsustainable advantage – arise, increase, and go extinct.

Applications

Differing evolutionarily stable strategies

The problem with group selection is that for a whole group to get a single trait, it must spread through the whole group first by regular evolution. But, as J. L. Mackie suggested, when there are many different groups, each with a different evolutionarily stable strategy, there is selection between the different strategies, since some are worse than others. For example, a group where altruism was universal would indeed outcompete a group where every creature acted in its own interest, so group selection might seem feasible; but a mixed group of altruists and non-altruists would be vulnerable to cheating by non-altruists within the group, so group selection would collapse.

Implications in population biology

Social behaviors such as altruism and group relationships can impact many aspects of population dynamics, such as intraspecific competition and interspecific interactions. In 1871, Darwin argued that group selection occurs when the benefits of cooperation or altruism between subpopulations are greater than the individual benefits of egotism within a subpopulation. This supports the idea of multilevel selection, but kinship also plays an integral role because many subpopulations are composed of closely related individuals. An example of this can be found in lions, which are simultaneously cooperative and territorial. Within a pride, males protect the pride from outside males, and females, who are commonly sisters, communally raise cubs and hunt. However, this cooperation seems to be density dependent. When resources are limited, group selection favors prides that work together to hunt. When prey is abundant, cooperation is no longer beneficial enough to outweigh the disadvantages of altruism, and hunting is no longer cooperative.

Interactions between different species can also be affected by multilevel selection. Predator-prey relationships can also be affected. Individuals of certain monkey species howl to warn the group of the approach of a predator. The evolution of this trait benefits the group by providing protection, but could be disadvantageous to the individual if the howling draws the predator's attention to them. By affecting these interspecific interactions, multilevel and kinship selection can change the population dynamics of an ecosystem.

Multilevel selection attempts to explain the evolution of altruistic behavior in terms of quantitative genetics. Increased frequency or fixation of altruistic alleles can be accomplished through kin selection, in which individuals engage in altruistic behavior to promote the fitness of genetically similar individuals such as siblings. However, this can lead to inbreeding depression, which typically lowers the overall fitness of a population. However, if altruism were to be selected for through an emphasis on benefit to the group as opposed to relatedness and benefit to kin, both the altruistic trait and genetic diversity could be preserved. However, relatedness should still remain a key consideration in studies of multilevel selection. Experimentally imposed multilevel selection on Japanese quail was more effective by an order of magnitude on closely related kin groups than on randomized groups of individuals.

Gene-culture coevolution in humans

Gene-culture coevolution allows humans to develop complex artefacts like elaborately decorated temples
Humanity has developed extremely rapidly, arguably through gene-culture coevolution, leading to complex cultural artefacts like the gopuram of the Sri Mariammam temple, Singapore.

Gene-culture coevolution (also called dual inheritance theory) is a modern hypothesis (applicable mostly to humans) that combines evolutionary biology and modern sociobiology to indicate group selection. It is believed that this approach of combining genetic influence with cultural influence over several generations is not present in the other hypotheses such as reciprocal altruism and kin selection, making gene-culture evolution one of the strongest realistic hypotheses for group selection. Fehr provides evidence of group selection taking place in humans presently with experimentation through logic games such as prisoner's dilemma, the type of thinking that humans have developed many generations ago.

Gene-culture coevolution allows humans to develop highly distinct adaptations to the local pressures and environments more quickly than with genetic evolution alone. Robert Boyd and Peter J. Richerson, two strong proponents of cultural evolution, postulate that the act of social learning, or learning in a group as done in group selection, allows human populations to accrue information over many generations. This leads to cultural evolution of behaviors and technology alongside genetic evolution. Boyd and Richerson believe that the ability to collaborate evolved during the Middle Pleistocene, a million years ago, in response to a rapidly changing climate.

In 2003, the behavioral scientist Herbert Gintis examined cultural evolution statistically, offering evidence that societies that promote pro-social norms have higher survival rates than societies that do not. Gintis wrote that genetic and cultural evolution can work together. Genes transfer information in DNA, and cultures transfer information encoded in brains, artifacts, or documents. Language, tools, lethal weapons, fire, cooking, etc., have a long-term effect on genetics. For example, cooking led to a reduction of size of the human gut, since less digestion is needed for cooked food. Language led to a change in the human larynx and an increase in brain size. Projectile weapons led to changes in human hands and shoulders, such that humans are much better at throwing objects than the closest human relative, the chimpanzee.

In 2015, William Yaworsky and colleagues surveyed the opinions of anthropologists on group selection, finding that these varied with the gender and politics of the social scientists concerned. In 2019, Howard Rachlin and colleagues proposed group selection of behavioural patterns, such as learned altruism, during ontogeny parallel to group selection during phylogeny.

Criticism

The use of the Price equation to support group selection was challenged by van Veelen in 2012, arguing that it is based on invalid mathematical assumptions.

Advocates of the gene-centered view of evolution such as Dawkins and Daniel Dennett remain unconvinced about group selection. Dawkins suggests that group selection fails to make an appropriate distinction between replicators and vehicles. The evolutionary biologist Jerry Coyne summarizes the arguments in The New York Review of Books in non-technical terms as follows:

Group selection isn't widely accepted by evolutionists for several reasons. First, it's not an efficient way to select for traits, like altruistic behavior, that are supposed to be detrimental to the individual but good for the group. Groups divide to form other groups much less often than organisms reproduce to form other organisms, so group selection for altruism would be unlikely to override the tendency of each group to quickly lose its altruists through natural selection favoring cheaters. Further, little evidence exists that selection on groups has promoted the evolution of any trait. Finally, other, more plausible evolutionary forces, like direct selection on individuals for reciprocal support, could have made humans prosocial. These reasons explain why only a few biologists, like [David Sloan] Wilson and E. O. Wilson (no relation), advocate group selection as the evolutionary source of cooperation.

The psychologist Steven Pinker states that "group selection has no useful role to play in psychology or social science", since in these domains it "is not a precise implementation of the theory of natural selection, as it is, say, in genetic algorithms or artificial life simulations. Instead [in psychology] it is a loose metaphor, more like the struggle among kinds of tires or telephones."

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