iiinova — where your digital self keeps evolving

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Jorge Peña 🇵🇸 @jorgeapenas.bsky.social · 08/10/2026

New preprint with Julian Garcia & @tobyhandfield.bsky.social 🧵 We tested 1,048,576 moral systems of indirect reciprocity, each pairing a strategy (how to act) with a social norm (how to judge others), across all prisoner's dilemmas, snowdrift games and stag hunts. arxiv.org/abs/2610.03832 1/6

Model diagram. Two players, each with a good or bad reputation, play a two-by-two game with payoffs R, S, T and P. Each player cooperates or defects according to a strategy table that reads both players' reputations. An observer watches and assigns both players new reputations according to a social norm table that reads both reputations and both actions. Side panels show example strategies (ALLC, ALLD, DISC, CDISC, ODISC, PDISC) and norms (Scoring, Stern Judging, Simple Standing, Standing, Consistent Standing, Generous Standing) as colored grids.

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Piret Avila @piretavila.bsky.social · 12/10/2026

New paper in Theoretical Population Biology with Laurent Lehmann: “Life history evolution and uninvadable mortality schedules with and without intergenerational energy transfers” 🧵 www.sciencedirect.com/science/arti...

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Joshua B. Plotkin @jplotkin.bsky.social · 10/08/2026

Happy to share a new paper led by the terrific Anzhi Sheng. We find that allocation policies that promote cooperation tend to concentrate benefits among the well-connected. And so structured societies must weigh collective success against the inequality it generates. www.nature.com/articles/s41...

Cooperation conflicts with equality when allocating public goods

Anzhi Sheng, Qi Su, Alex McAvoy, Long Wang & Joshua B. Plotkin
Nature 655, 1217-1225 (2026)

Cooperation is typically seen as the ideal outcome in a social dilemma. Because cooperators are vulnerable to exploitation, much of the literature has focused on mechanisms, such as spatial structure, that support prosocial behaviour and the production of public goods1,2,3,4,5,6,7,8,9,10,11. Yet the rules for distributing these goods also shape behaviour and long-term prosperity. Here we study policies for allocating public goods, comparing equitable allocation, in which returns are proportional to potential contributions, with uniform allocation, in which all individuals receive equal shares. For most social networks, we find that uniform allocation facilitates the spread of cooperation compared with equitable allocation. But this success comes with a cost. Uniform allocation concentrates resources in a small number of highly connected individuals12, whereas peripheral individuals receive fewer benefits and may even be worse off than in a non-cooperative society. We develop a theoretical analysis of the tension between cooperation and equality, and we identify this conflict across diverse empirical social networks. Our results show that inequality may be an unavoidable consequence of allocation policies designed to foster cooperation in spatially heterogeneous populations. The question of how to promote cooperation is therefore incomplete: because policies that facilitate cooperation can also generate social stratification, we must weigh the benefits of cooperation against the inequality that accompanies it.

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Dominik Deffner @dominikdeffner.bsky.social · 10/07/2026

Learning from the most successful people makes sense? We show that social learning, and especially payoff bias, is bad when choice outcomes are dependent on prior success💰 As such "rich-get-richer" dynamics are everywhere, this shows fundamental boundary conditions for the benefits of SL!

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Jeff Yoshimi @jyoshimi.bsky.social · 06/08/2026

I first learned dynamical systems theory from “Dynamics: the Geometry of Behavior” (1992), a collaboration between mathematician Ralph Abraham and artist Chris D Shaw. The book is over 600 pages long, and the visualizations stay strong and groovy the whole time.

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Paul Smaldino @psmaldino.bsky.social · 30/07/2026

A Demographic Theory of Similarity-Biased Social Learning. Now out in PNAS, led by the incomparable @apvelilla.bsky.social . We use modeling to explore conditions for the (cultural) evolution of parochial (and anti-parochial) learning biases. www.pnas.org/doi/10.1073/...

Humans adapt by learning from others, but risk acquiring maladaptive behaviors when learning from individuals facing different conditions. We present an evolutionary model exploring how individuals use social identity markers to select learning targets in diverse populations. Learners evolve biases that track reliable information sources: preferring similar individuals when in-group knowledge is adaptive, and dissimilar individuals when in-group behaviors are disadvantageous. Our framework demonstrates that this adaptive bias makes social learning viable even when it is costlier than individual learning. Additionally, we show that a minimum threshold of reliable cultural information is required for social learning to spread, providing a mathematical explanation for how demographic diversity drives population-level patterns of cultural segregation and assimilation.

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xuan (ɕɥɛn / sh-yen) @xuanalogue.bsky.social · 25/07/2026

I wasn't able to attend #CogSci26 this year, but happy to share that a paper I presented there two years ago is now published in journal-length form 😊 The paper studies how people can rationally infer others' goals in open-ended spaces, and yet do so rapidly and spontaneously.

Topics in Cognitive Science
Original Article
Open Access
Infinite Ends From Finite Samples: Open-Ended Goal Inference as Top-Down Bayesian Filtering of Bottom-Up Proposals
Tan Zhi-Xuan, Gloria Kang, Vikash Mansinghka, Joshua B. Tenenbaum

Open-ended goal inference as top-down Bayesian filtering of bottom-up proposals. We model inference in open-ended goal spaces as the combination of two processes: (a) Bottom-up sampling—you (observer) see your friend (agent) enter the kitchen and come up with several plausible goals (making tea, getting a snack, grabbing drinks, checking the pot, and so on) based on the context cue that your friend is in the kitchen. (b) Top-down filtering—your friend opens the fridge, which would be irrational if they were making tea or checking the pot; these goals are hence filtered out as poor explanations. By repeating these processes as actions unfold, we can model how people draw broadly rational inferences about others' goals even when the space of possibilities is infinite or just too large for explicit enumeration.

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Paul Smaldino @psmaldino.bsky.social · 22/07/2026

I really like this paper I did with @nathan-gabriel.bsky.social and @avbell.bsky.social, now out in EHS. It's an unusual paper because we tried to model the emergence of complex, multidimensional and intersectional identity structures from a signaling perspective. www.cambridge.org/core/journal...

The evolution of identity signals for co-ordination in diverse societies
Individual social identities indicate group affiliations and are typically associated with group-typical preferences, signals that indicate group membership, and the propensity to condition actions on the social signals of others, resulting in group-differentiated interaction norms. Past work modelling identity signalling and co-ordination has typically assumed that individuals belong to one of a discrete set of groups. Yet individuals can simultaneously belong to multiple groups, which may be nested within larger groupings. Here, we introduce the generalized Bach or Stravinsky game, a co-ordination game with ordered preferences, which allows us to construct a model that captures the overlapping and hierarchical nature of social identity. Our model unifies several prior results into a single framework, including results related to co-ordination, minority disadvantage, and cross-cultural competence. Our model also allows agents to express complex social identities through multidimensional signalling, which we use to explore a variety of complex group structures. Our consideration of intersectional identities exposes flaws in naive measures of group structure, illustrating how empirical studies may overlook some social identities if they do not consider the behaviours that those identities function to afford.

Figure 1.
(a) Ancient Sumerian cities used throughout the paper as a motivating example. (b) Diagram of relationships between the different Mesopotamian identities along with shapes used to represent each of them throughout the paper.

Figure 11.
Proportion of simulations that resulted in (a) the intersectional structure, optimal when 𝛼 =2, or (b) either of the two mere conjunction structures, optimal when 𝛼 =0. The trio of stick figures at the top represent the optimal strategy profiles used by non-Kishus in all cases.

Acknowledgements
We thank the members of the MODSOC lab at UC Merced for helpful comments. We are grateful to the NSF for funding foundational research on social identity, inequality, and intersectionality.

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Paul Smaldino @psmaldino.bsky.social · 20/07/2026

Want to do a PhD to work on models of opinion dynamics and the inequalities of information flow, with an emphasis on climate change and climate policy? Apply by October 15 to work with Ago Merico and myself, based at @leibniz-zmt.de in Bremen, Germany. www.leibniz-zmt.de/en/vacancies...

leibniz-zmt.de

Doctoral candidate (gn) - WG Systems Ecology

Das Leibniz-Zentrum für Marine Tropenforschung (ZMT) erforscht tropische und subtropische Küstenökosysteme und ihre Bedeutung für Natur und Menschen erforscht.

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Oleg Sobchuk 🇺🇦 @sobchuk.bsky.social · 29/06/2026

📣 I'm hiring! Two positions (PhD student & Postdoc) in my ERC project Macroevolution of European Literature. Let's study the cultural evolution of literature using massive data 📚📈 📍Frankfurt | Apply by August 15 Details: www.aesthetics.mpg.de/en/career/jo... Please repost to help spread the word!

Job announcement of two positions at the Max Planck Institute for Empirical Aesthetics in Frankfurt: postdoc (Macroevolution of European Literature) and PhD student (Computational Literary Studies). Successful candidates will be affiliated with the research group Cultural Evolution of the Arts.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/07/2026

True 😂 perhaps a clunky attempt at commodification at best.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/07/2026

Commodification is perhaps the term that best captures this.

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Paul Smaldino @psmaldino.bsky.social · 15/07/2026

I had a paper accepted and learned that PNAS got rid of their free, “closed access” (preprint ok) option - they now charge at least $3K to publish because they are greedy little pigs who have no shame.

PNAS charges $5575 for immediate access at $3925 for delayed open access, because they are greedy pigs without shame.

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Bret Beheim @babeheim.bsky.social · 06/06/2026

Watch out, he's got a PhD! Congrats man!

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Paul Smaldino @psmaldino.bsky.social · 06/06/2026

I couldn’t be prouder of the stellar work @apvelilla.bsky.social did for his PhD. A phenomenal set of work on social learning, cooperation, and risk. Keep on eye on this guy, he’s one to watch.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 06/06/2026

There, I will be joining the Cooperative Systems and Intelligence Lab under @xuanalogue.bsky.social, where we will work on cool new projects at the intersection of cooperative intelligence/AI alignment and cultural evolution. Onwards to glory!

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Alejandro Pérez Velilla @apvelilla.bsky.social · 06/06/2026

I am also excited to announce that I will start a new position this Fall as Research Fellow at the Computer Science department of the National University of Singapore.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 06/06/2026

I am deeply thankful to my mentors, colleagues and committee members for five years of hard, but ultimately very fulfilling work. Shoutout to @babeheim.bsky.social, @elspethready.bsky.social, @jorgeapenas.bsky.social, @tylermarghetis.bsky.social, @juemos.bsky.social for all the input and guidance!

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Alejandro Pérez Velilla @apvelilla.bsky.social · 06/06/2026

I am happy to announce that I have successfully defended my dissertation --- under the supervision of my mentor @psmaldino.bsky.social --- for the title of Doctor of Philosophy in Cognitive and Information Sciences at the University of California, Merced.

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Ketika Garg @ketikagarg.bsky.social · 01/12/2024

1st post on bsky - about bsky! I was fascinated with academic starter packs and made an interactive network to see academic communities and how they connect - a map of knowledge! link to an interactive & searchable network: ketikagarg.github.io/blueSkyAcade...

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Mason Youngblood @masonyoungblood.bsky.social · 24/03/2026

New paper out today! When baby zebra finches are tutored with manipulated songs with shuffled syllables, they transform them to be consistent with linguistic laws 🐥 Reanalysis of data from James and Sakata (2017) link.springer.com/article/10.1...

link.springer.com

Zebra finches transform manipulated songs with shuffled syllables to exhibit linguistic laws - Animal Cognition

Animal Cognition - Linguistic laws are increasingly used as markers of efficiency in non-human communication, but it remains unclear how rapidly these patterns can emerge. In this re-analysis of...

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Dominik Deffner @dominikdeffner.bsky.social · 02/03/2026

Come work with us! And get in touch with any questions you might have about the position, our labs or living/working in Germany #PostdocWanted

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Paul Smaldino @psmaldino.bsky.social · 24/02/2026

Great thread by @apvelilla.bsky.social about our new paper: "A Demographic Theory of Similarity-Biased Social Learning." We use mathematical modeling to explore the functional role played by identity markers in how we learn from others, and in the evolution of social learning more generally.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

This work is part of the first half of my dissertation, which deals with the theme of social learning under uncertainty and risk. Only two more projects to go! Feedback is very welcome!

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

In other words, density-dependent costs lead the population to evolve past the point of maximum efficiency. While this leads to the evolution of mixed social learning, it ends up granting the same fitness benefits that pure individual learners obtain with no social learning at all.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

This rescue can be so effective as to lead social learning to fixation. However, if we assume a density-dependent cost to social learning, social learning can stabilize at an intermediate frequency, recovering "Rogers' paradox".

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

This "rescue" depends on how informative tags are: when the correlation between tags and behavioral correctness is strong, optimal bias becomes useful enough that, at high enough frequencies of social learning, its benefits offset the costs of social learning with respect to individual learning.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

Our setup also shows that bias can actually "rescue" social learning, even when unbiased social learning is costlier than individual learning. However, this can only happen when social learning is common enough to build a cultural pool rich enough to bootstrap the benefits of social learning.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

We extend this idea to the possibility of anti-bias, where agents preferentially learn from targets whose tags are associated with out-group membership. Doing so allows us to get a richer picture of how demographic mixing and ecological structure lead to different strength and direction of bias.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

In our previous paper we found that a similarity bias---which exploits group identity information contained in visible tags---is favored when identity tags are correlated with behavioral correctness. In diverse pops with group-structured ecological niches, parochialism evolves to avoid mismatch.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 24/02/2026

New preprint with @psmaldino.bsky.social on the evolution of similarity-biased learning: osf.io/preprints/so... This mathematical treatment both simplifies and extends our previous simulation treatment of the subject: www.cambridge.org/core/journal...

osf.io

OSF

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/12/2025

A highlight of our approach is that, by parameterizing the possible underlying communication networks and their role in how agents decide to share, we can potentially use observed network data to infer properties of the unobserved communication networks driving them. Comments welcome!

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/12/2025

This tells us the mechanism is likely a strong contributor to observable sharing network structure, but since real networks are the product of many different mechanisms (such as kin-based sharing and risk pooling) it should not be leveraged in isolation.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/12/2025

We then fit the simulation model to data from a community in the Canadian Arctic, showing that our "network signaling" mechanism can explain several aspects of the empirical sharing network structure (while missing the mark on others, such as reciprocity).

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/12/2025

Our model reveals a neat insight: agents will find it advantageous to share widely when the underlying communication networks through which reputation travels are connected but sparse. As comm. networks become denser, agents find that few sharing partners are needed to spread signals of generosity.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/12/2025

Here we explore how signaling on a (unobserved) communication network can lead to the (observed) sharing networks in forager communities. We formalize the mechanism through a game-theoretic model which we then turn into a strategic network formation model that simulates network data.

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Alejandro Pérez Velilla @apvelilla.bsky.social · 16/12/2025

New preprint out with @elspethready.bsky.social : "The emergence of sharing networks through indirect signaling". osf.io/preprints/so...

osf.io

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Paul Smaldino @psmaldino.bsky.social · 09/12/2025

Super proud of this paper with @apvelilla.bsky.social and @babeheim.bsky.social, now out in Psych Review. Non-paywalled version (preprint) here: osf.io/preprints/so...

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Zach Weinersmith @zachweinersmith.bsky.social · 08/12/2025

Full comic here: www.smbc-comics.com/comic/capita... #smbc

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Evolutionary Psychology (the podcast) @epthepod.bsky.social · 04/11/2025

This week we talk to @babeheim.bsky.social about culture, change, modeling, running red lights, and the game of go. youtu.be/nqTkSK-qtJM www.podbean.com/eas/pb-hrn9v...

youtu.be

Cultural Dynamics with Bret Breheim

YouTube video by Evolutionary Psychology (The Podcast)

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Paul Smaldino @psmaldino.bsky.social · 30/09/2025

Happy to see this work published in Psych Review. It's an impressive and important bit of theory/modeling about how we learn about decision-making under risk. Here's a slide with the super-coarse-grained summary of our results. Read the paper for (much) more. osf.io/preprints/so...

Modeling the evolution of peer and vertical/oblique learning strategies for gambles under uncertainty
We recover many empirical results and generate new hypotheses:
Worse conditions lead to more pessimistic behavior
Younger people are overly optimistic
Wealthy people can afford to take more risks
Payoff-biased learning for the rich, parochialism for the poor
Poor people may be slower to adapt to environmental change, creating the appearance of “poverty traps”

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Alejandro Pérez Velilla @apvelilla.bsky.social · 28/09/2025

Whoops, that's the wrong link to the commentary. The right link is this one: osf.io/preprints/so...

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Alejandro Pérez Velilla @apvelilla.bsky.social · 27/09/2025

We believe these ideas can help explain behavioral variation in many domains by specifying how risk landscapes shape beliefs and behavior through learning strategies. See our (in press) commentary to the (great) target article by @sheinalew.bsky.social & @dorsaamir.bsky.social osf.io/preprints/so...

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Alejandro Pérez Velilla @apvelilla.bsky.social · 27/09/2025

@psmaldino.bsky.social and I also made a contribution to the Oxford Handbook of Evolutionary Psychology on how an integrative view spanning evolutionary, developmental and cultural influences on risk behavior can help us understand decisions under risk—a good companion piece. osf.io/preprints/so...

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Alejandro Pérez Velilla @apvelilla.bsky.social · 27/09/2025

I am happy to announce that our project on risk and social learning is now in press at Psychological Review. Several new additions and revisions thanks to detailed feedback from colleagues and anonymous reviewers. osf.io/preprints/so... @psmaldino.bsky.social @babeheim.bsky.social

osf.io

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Alejandro Pérez Velilla @apvelilla.bsky.social · 27/09/2025

osf.io

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Bret Beheim @babeheim.bsky.social · 16/09/2025

How to quantify the impact of AI on long-run cultural evolution? Published today, I give it a go! 400+ years of strategic dynamics in the game of Go (Baduk/Weiqi), from feudalism to AlphaGo!

Miyagawa Shuntei's 1898 painting, "Playing Go (Japanese Chess)"

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