I am interested in social behavior, decision-making, and biases in a variety of systems. Below, please find my articles grouped by theme, and click on any title to view the paper. For the most updated list of publications and preprints, here is my Google Scholar profile. Image credit: OpenAI's GPT-5.3.
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I. Conformity and Anticonformity
Summary: Conformist and anticonformist biases in acquiring cultural variants have been documented in humans and several nonhuman species. We introduce a framework for quantifying these biases when cultural traits are ordered, with greater and lesser values, and either continuous (e.g., level of a behavior) or discrete (e.g., number of displays of a behavior). Unlike previous models, we do not measure a cultural variant’s popularity by its distance to the population mean, but rather by its distance to other variants. We find that conformity can produce a variety of population distributions that need not center around the initial population’s mean variant. Anticonformity may lead to highly polarized or uniformly distributed populations, depending on its strength and on individuals’ precision when copying others.
Summary: Polychotomous traits (i.e., traits with more than two variants) are ubiquitous in nature, from phonemes to food sources. Individuals may adopt variants nonrandomly, influenced by biases including conformity and anticonformity. Mathematical models of (anti)conformity to a dichotomous trait, with two variants, are widely accepted, but fewer conformity models incorporate more than two discrete variants, and in those that do, the level of conformity is determined by a single coefficient. We generalize standard dichotomous trait conformity models—where there may be different conformity coefficients depending on the numbers of sampled variants—to include m variants. Frequency dynamics, including polymorphic equilibria, stable cycles, and chaos, can differ from what is known for a trait with only two variants.
Summary: The evolutionary dynamics of cultural variants under conformist- and anticonformist-biased transmission have implications for humans and nonhuman animals. Humans display both conformist and anticonformist biases, and models of conformist-biased transmission have been proposed to explain large-scale human cooperation. Nonhuman animals have been shown to display conformist biases in mating and foraging decisions. Here, we investigate established mathematical models of conformist and anticonformist bias with and without selection and find complex dynamics, including multiple stable polymorphic equilibria, stable cycles, and chaos. Using modifier theory, we show that evolution will reduce anticonformist bias against a culturally advantageous variant. Migration between subpopulations subject to different selection and conformity pressures can produce interesting polymorphisms or eliminate between-group differences.
Selected other research on conformity and anticonformity
II. Coevolution
(Coming soon!) On culture-culture and gene-culture coevolution under fertility or viability selection
Denton KK*, Fogarty L*, Zhang S, Feldman MW. (In press.) Population Biology Modeling & Theory. (*Co-first authors)
Abstract will be posted soon!
Denton KK, Kendal JR, Ihara Y, Feldman, MW. (2023). Theoretical Population Biology, 153: 1-14.
In memory of our colleague and friend Freddy Christiansen.
Abstract: The evolution of a cultural trait may be affected by niche construction, or changes in the selective environment of that trait due to the inheritance of other cultural traits that make up a cultural background. This study investigates the evolution of a cultural trait, such as the acceptance of the idea of contraception, that is both vertically and horizontally transmitted within a homogeneous social network. Individuals may conform to the norm, and adopters of the trait have fewer progeny than others. In addition, adoption of this trait is affected by a vertically transmitted aspect of the cultural background, such as the preference for high or low levels of education. Our model shows that such cultural niche construction can facilitate the spread of traits with low Darwinian fitness while providing an environment that counteracts conformity to norms. In addition, niche construction can facilitate the ‘demographic transition’ by making reduced fertility socially accepted.
III. Major Evolutionary Transitions
Nonacs P, Denton KK. (2024). Insectes Sociaux, 71: 17-27.
Abstract: Major evolutionary transitions (METs) across Earth’s biological history describe fusions of lower-level entities into higher-level individuals (evolutionary transitions in individuality: ETIs) as well as novel forms of information storage and transmission (Information Leaps). Obligate eusociality is frequently listed as a MET—most often in the context of being an ETI and with an extrapolation that the ETI requires inclusive fitness maximization for all parties. However, obligate eusociality neither fundamentally alters how information is stored and transmitted nor meets the various criteria proposed for an ETI. We argue that rather than representing a higher-level individual, the evolution of non-reproductive worker castes is more analogous to a novel ‘organ’ that maintains homeostasis and nurtures the gonadal tissue of mated queens. Worker castes benefit queens by performing dangerous but necessary functions such as foraging, while enabling the gamete-producing functions to be kept relatively safe. This is an ecologically successful and significant evolutionary innovation, which can be thought of as a major competitive transition (MCT). In this context, we hypothesize that worker castes are most likely to evolve through parental manipulation. Employing such a MCT perspective generates a broad series of predictions about eusocial life histories.
Abstract: The emergence of human societies with complex language and cumulative culture is considered a major evolutionary transition. Why such a high degree of cumulative culture is unique to humans is perplexing given the potential fitness advantages of cultural accumulation. Here, Boyd & Richerson’s (1996 Why culture is common, but cultural evolution is rare. Proc. Br. Acad. 88, 77–93) discrete-cultural-trait model is extended to incorporate arbitrarily strong selection; conformist, anti-conformist and unbiased frequency-dependent transmission; random and periodic environmental variation; finite population size; and multiple ‘skill levels.’ From their infinite-population-size model with success bias and a single skill level, Boyd and Richerson concluded that social learning is favoured over individual learning under a wider range of conditions when social learning is initially common than initially rare. We find that this holds only if the number n of individuals observed by a social learner is sufficiently small, but with a finite population and/or a combination of success-biased and conformist or unbiased transmission, this result holds with larger n. Assuming social learning has reached fixation, the increase in a population’s mean skill level is lower if cumulative culture is initially absent than initially present, if population size is finite, or if cultural transmission has a frequency-dependent component. Hence, multiple barriers to cultural accumulation may explain its rarity.
Abridged abstract: A small number of extraordinary “Major Evolutionary Transitions” (METs) have attracted attention among biologists. They comprise novel forms of individuality and information, and are defined in relation to organismal complexity, irrespective of broader ecosystemlevel effects. This divorce between evolutionary and ecological consequences qualifies unicellular eukaryotes, for example, as a MET although they alone failed to significantly alter ecosystems. Additionally, this definition excludes revolutionary innovations not fitting into either MET type (e.g., photosynthesis). We recombine evolution with ecology to explore how and why entire ecosystems were newly created or radically altered – as Major System Transitions (MSTs). In doing so, we highlight important morphological adaptations that spread through populations because of their immediate, direct-fitness advantages for individuals. These are Major Competitive Transitions, or MCTs. We argue that often multiple METs and MCTs must be present to produce MSTs. For example, sexually-reproducing, multicellular eukaryotes (METs) with anisogamy and exoskeletons (MCTs) significantly altered ecosystems during the Cambrian. Therefore, we introduce the concepts of Facilitating Evolutionary Transitions (FETs) and Catalysts as key events or agents that are insufficient themselves to set a MST into motion, but are essential parts of synergies that do.
IV. Artificial Intelligence
(Preprint) Do AI models perform human-like abstract reasoning across modalities?
Beger C, Yi R, Fu S, Denton KK, Moskvichev A, Tsai SW, Rajamanickam S, Mitchell M. (2025). arXiv:2510.02125.
Abstract: OpenAI's o3-preview reasoning model exceeded human accuracy on the ARC-AGI-1 benchmark, but does that mean state-of-the-art models recognize and reason with the abstractions the benchmark was designed to test? Here we investigate abstraction abilities of AI models using the closely related but simpler ConceptARC benchmark. Our evaluations vary input modality (textual vs. visual), use of external Python tools, and reasoning effort. Beyond output accuracy, we evaluate the natural-language rules that models generate to explain their solutions, enabling us to assess whether models recognize the abstractions that ConceptARC was designed to elicit. We show that the best models' rules are frequently based on surface-level "shortcuts," capturing intended abstractions considerably less often than humans. In the visual modality, AI models' output accuracy drops sharply; however, our rule-level analysis reveals that a substantial share of their rules capture the intended abstractions, even as the models struggle to apply these concepts to generate correct solutions. In short, we show that using accuracy alone to evaluate abstract reasoning can substantially overestimate AI capabilities in textual modalities and underestimate it in visual modalities. Our results offer a more faithful picture of AI models' abstract reasoning abilities and a more principled way to track progress toward human-like, abstraction-centered intelligence.
V. Altruism and Morality
Denton KK, Ram Y, Feldman MW. (2022). Theoretical Population Biology, 143: 52-61.
Abstract: The evolution of altruism has been extensively modeled under the assumption of genetic transmission, whereas the dynamics under cultural transmission are less well understood. Previous research has shown that cultural transmission can facilitate the evolution of altruism by increasing (1) the probability of adopting the altruistic phenotype, and (2) assortment between altruists. We incorporate vertical and oblique transmission, which can be conformist or anti-conformist, into models of parental care, sibling altruism, and altruism between individuals that meet assortatively. If oblique transmission is conformist, it becomes easier for altruism to invade a population of non-altruists as the probability of vertical transmission increases. If oblique transmission is anti-conformist, decreasing vertical transmission facilitates invasion by altruism in the assortative meeting model, whereas in other models, there is a trade-off: greater vertical transmission produces greater assortment among genetically related altruists, but lowers the probability of adopting altruism via anti-conformity. Compared to conditions for invasion under genetic transmission, e.g., Hamilton’s rule, we show that invasion can be easier with sufficiently strong anti-conformity, and in some models, with sufficiently high assortment even if oblique transmission is conformist. We also explore invasion by an allele A that increases individuals’ content bias for altruism, in the absence of other forms of cultural transmission. If costs and benefits combine additively, A invades under previously known conditions. If costs and benefits combine multiplicatively, invasion by A and by altruism become more difficult than in the corresponding additive models.
Denton KK, Krebs DL. (2017). Evolutionary Psychological Science, 3(1), 72-85.
Abstract: Some scholars have contended that moral decision-making is primarily rational, mediated by controlled, deliberative, and reflective forms of moral reasoning. Others have contended that moral decision-making is primarily emotional, mediated by automatic, affective, and intuitive forms of decision-making. Evidence from several lines of research suggests that people make moral decisions in both of these ways. In this paper, we review psychological and neurological evidence supporting dual-process models of moral decision-making and discuss research that has attempted to identify triggers for rational-reflective and emotional-intuitive processes. We argue that attending to the ways in which brain mechanisms evolved and develop throughout the life span supplies a basis for explaining why people possess the capacity to engage in two forms of moral decision-making, as well as accounting for the attributes that define each type and predicting when the mental mechanisms that mediate each of them will be activated and when one will override the other. We close by acknowledging that neurological research on moral decision-making mechanisms is in its infancy and suggesting that future research should be directed at distinguishing among different types of emotional, intuitive, rational, and reflective processes; refining our knowledge of the brain mechanisms implicated in different forms of moral judgment; and investigating the ways in which these mechanisms interact to produce moral decisions.
Other, non-journal publications on altruism, morality, and related themes
Krebs DL, Denton KK. (2017). The evolution of sociality, helping, and morality. In P. Zuckerman and J. R. Shook (Eds.) The Oxford Handbook of Secularism, pp. 638-654. Oxford University Press.
Denton KK. (2016). Iterated Prisoner’s Dilemma model. In T. Shackelford and V. Weekes-Shackelford (Eds.) Encyclopedia of Evolutionary Psychological Science. Switzerland: Springer.
Denton KK, Krebs DL. (2016). Symbiosis and mutualism. In T. Shackelford and V. Weekes-Shackelford (Eds.) Encyclopedia of Evolutionary Psychological Science. Switzerland: Springer.
Krebs DL, Denton KK. (2016). Group selection. In H. Miller Jr. (Ed.) SAGE Encyclopedia of Theory in Psychology, Vol. 1, pp. 392-393.
Krebs DL, Denton KK. (2013). How did morality originate? A review of Christopher Boehm, Moral Origins: The Evolution of Virtue, Altruism, and Shame. Evolutionary Psychology, 11(1), 9-17.
VI. Experimental Work on Social Signaling
Bryant GA, Fessler DMT, Fusaroli R, Clint E, Amir D, Chavez B, Denton, KK, Diaz C, Duran LT, Fančovičová J, Fux M, Ginting EF, et al. (2018). Psychological Science, 29(9), 1515-1525.
Abstract: Laughter is a nonverbal vocalization occurring in every known culture, ubiquitous across all forms of human social interaction. Here, we examined whether listeners around the world, irrespective of their own native language and culture, can distinguish between spontaneous laughter and volitional laughter—laugh types likely generated by different vocal-production systems. Using a set of 36 recorded laughs produced by female English speakers in tests involving 884 participants from 21 societies across six regions of the world, we asked listeners to determine whether each laugh was real or fake, and listeners differentiated between the two laugh types with an accuracy of 56% to 69%. Acoustic analysis revealed that sound features associated with arousal in vocal production predicted listeners’ judgments fairly uniformly across societies. These results demonstrate high consistency across cultures in laughter judgments, underscoring the potential importance of nonverbal vocal communicative phenomena in human affiliation and cooperation.
Denton KK, Nonacs P. (2018). Animal Behaviour, 141, 77-84.
Abstract: Cooperatively foraging groups have two sequential goals: to find food and thereafter efficiently exploit or retrieve it. Previous research has largely focused on searching behaviours of individuals or organization of food retrieval processes, rather than on how groups initially distribute themselves to find ephemeral food items that are unpredictable in time and space. In the present study, we examined how Argentine ants, Linepithema humile, search environments in anticipation of food appearing briefly in areas with differing spatial complexity. Nests were connected to three foraging arenas containing 1, 9 or 25 cells. Food appeared briefly in one cell each day, either randomly or more predictably in distant cells (but equally often in each arena). We recorded the number of ants in cells when food had not been recently present, and thereafter whether ants successfully located the food when presented. Surprisingly, as food location became more predictable, ants found it less frequently. Foragers were located more often in cells closer to the nest (i.e. at information ‘choke points’ that returning foragers needed to traverse), and in cells with higher connectivity and greater centralness within foraging arenas. Such distributions reduce search coverage area but likely increase information transmission. Thus, it appears that L. humile foragers distribute themselves to favour rapid recruitment when food is found rather than maximizing food encounter rates. Although the reduced foraging success with more predictably located food suggests that ants did not adjust expectations in a Bayesian manner within arenas towards individual cells, they did appear Bayesian across arenas. Because foragers missed food more often in higher-complexity arenas than in lower-complexity arenas, this could increase perceptions that the latter are more rewarding. Shifts in distributions were consistent with such biased perceptions. Future studies to determine whether other group-foraging species use analogous solutions would be highly useful.
Hedley RW, Denton KK, Weiss RE. (2017). Animal Behaviour, 131, 23-32.
Abstract: Identifying the signalling strategies employed by animals during vocal interactions is a challenge, especially for species with large vocal repertoires. We propose that efforts to study such vocal dynamics can benefit by integrating models of syntax into their analyses. In this study, we conducted playback experiments on Cassin's vireo, Vireo cassinii, to examine the role of syntax, and more specifically, shared syntactic patterns, in countersinging. We presented 11 males with song sequences ordered according to population norms, and with sequences whose order deviated from population norms. We did not find evidence that individuals markedly altered their responses based on the syntax of the playback, either in their physical approach to the speaker or in the quantity of song they delivered in response. We did, however, find evidence that syntax was important in governing their choice of phrase types in response to the playbacks. Subjects did not match the playback phrase types. Instead, they engaged in a vocal behaviour referred to as song advancing, where they responded to a stimulus phrase type by singing the phrase type that most often followed the stimulus in their own normal song sequences. When playback sequences were ordered according to population norms, song advancing resulted in birds pre-empting the upcoming playback phrase type or delivering another of the prior playback phrase types (i.e. delayed matching) at higher rates than when playback sequences deviated from population norms. The detection of song advancing was only possible with the explicit inclusion of syntax in our analysis, suggesting that studies of the vocal interactions of species with repertoires of multiple vocalizations can benefit from consideration not only of a subject's repertoire, but also their syntax.
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