Biology subjects

Bickel, B.

Publications and source records attributed to Bickel, B..

17 recordsLinked to original sources

bioRxiv2026

Evolutionary dynamics of maximal syllable complexity show no universal bias rooted in jaw biomechanics

Linguistic evolution has given rise to variation in the degree of syllable complexity that any given language permits. However, several models of language converge in predicting a universal bias towards the consonant-vowel (CV) structure (or a broader strong-weak asymmetry). This is closely tied to incremental speech processing, and in evolutionary terms has been linked to certain rhythmic orofacial displays in non-human primates. Yet, whether linguistic evolution really reflects such a universal tendency is an open question, one that we aim to address using phylogenetic comparative methods. Modeling change according to a continuous-time Markov process, we estimate transition rates for maximal onset and coda sizes (i.e. grammatical rules) across 5 language families. We demonstrate that a lineage-specific model outperforms a global model, and further explore the nature of lineage-specific long-term preferences and rates of change on multiple levels. We show that the former drive inter-family variation more than the latter. Generally, particulars turn out to impact syllable complexity more than any universal biomechanically or neurocognitively motivated biases do, implying that evolutionary continuity with our primate ancestors may have been overstated for this domain of language.

evolutionary biology↗

bioRxiv2026

Supra-regular recursion in primate vocal sequences

Complex syntax is the widely accepted demarcation between animal and human communication. Although animal vocal systems occasionally contain pockets of syntax-like structures, their grammars are thought to be at best regular, whereas human language is supra-regular, i.e., including at least context-free computational complexity. Leveraging a new likelihood method for probabilistic formal grammars, we show that the call sequences of three phylogenetically diverse nonhuman primates (bonobos, olive colobus monkeys, common marmosets) include parts that are most likely generated by supra-regular recursive grammars, similar to human language. These findings challenge syntax as the major transition in hominid evolution and opens up prospects for alternative evolutionary scenarios.

animal behavior and cognition↗

bioRxiv2026

Cortico-hippocampal dynamics of hierarchical syntactic planning in natural speech production

The human brain must rapidly construct hierarchical structures to organize complex sequential behavior, yet the neural dynamics supporting this process during natural behavior remain poorly understood. Spoken language provides a powerful model system for investigating this computation, requiring rapid transformation of conceptual intent into structured sequential output. Using rare intracranial stereo-electroencephalography (SEEG) recordings from patients producing extended spontaneous speech, we examined how syntactic planning unfolds over time using measures of constituency, dependency structure, and probabilistic syntactic categories. We identified a hierarchical planning architecture in which global sentence structure and core syntactic categories (nouns and verbs) were specified before more local planning operations. Neural representations of these categories emerged up to 1 s before articulation and persisted throughout the planning period, whereas optional modifiers, including adjectives and adverbs, were recruited only closer to speech onset. These observations support a model of hierarchical incremental planning in which abstract sentence structure precedes the incremental specification of individual sentence elements. While core syntactic categories engaged a broader fronto-temporo-parietal network than other word classes, syntactic-depth-related activity emerged in parallel across cortical regions and the hippocampus, suggesting that hippocampal relational representations contribute to sentence structure building. Together, these findings support a cortico-hippocampal model of speech production in which hierarchical sentence structure and core syntactic categories are planned before secondary syntactic elements are incrementally incorporated into the evolving sentence plan. These results provide a neural account of how abstract linguistic structure is transformed into fluent speech.

neuroscience↗

bioRxiv2025

Linguistic evolution minimizes the amount of syntactic hierarchy in grammar

A core characteristic of language is the capacity for hierarchical syntax, but it remains debated to what extent languages favor hierarchical structure in their grammars, that is, the extent to which they favor hierarchical structures like "When driving, look ahead!" over concatenations like "You drive, you look ahead!". Through phylogenetic modeling of the grammars of clause combining in three extensive language families (Tupi-Guarani, Sino-Tibetan, and Indo-European), we find an overall bias towards minimizing hierarchy, with significant cultural variation. Our findings suggest that the computational and representational benefits of hierarchical structure tend not to be universally exploited in clause combinations, likely because they come with additional costs for learning. In consequence, the amount of hierarchy in language might differ from what is found in animal communication in a more graded way than commonly assumed.

evolutionary biology↗

bioRxiv2025

Writing does not Impact the Evolution of Syntax

The acquisition of writing has a lasting effect on how languages are processed in the brain, raising the possibility that it also affects how they are used and evolve over time. A popular hypothesis is that writing specifically leads to increased use and evolution of complex hierarchical structures in language. While most case studies on individual languages have supported this, it remains unclear whether results scale to larger and more diverse sets of languages. Here we test the prediction for language use by modeling hierarchy depth and sentence length in Universal Dependencies corpora from 30 languages, and the prediction for language evolution by modeling the phylogenetic dynamics of structural asymmetry in clause combinations of 59 languages from three families. We found no effect of writing in either analysis. Hierarchy depth and sentence length do not demonstrably differ between spoken and written use of language, and the introduction of writing had no discernible effect on the evolution of clause combining in grammar. There is weak evidence for a decrease in variance after the introduction of writing in one family, possibly reflecting the impact of increased normativity. In conclusion, our findings challenge popular beliefs about hierarchy and suggest that the evolution of syntax is more driven by culturally variable ideas about style in linguistic expression than by the evolution of writing.

evolutionary biology↗

bioRxiv2025

A Phylogenetic Perspective on the Syntax-Semantics Interface: A Case Study in Clause Linkage Constructions

We examine the syntax-semantics interface in clause linkage using a cross-linguistic sample of nearly 700 constructions from Indo-European, Sino-Tibetan, and Tupi-Guarani. To evaluate predictions from the Interclausal Relations Hierarchy, we model the phylogenetic dynamics of how semantic relations influence the degree of syntactic integration between clauses. The best performing model assumes an Ornstein-Uhlenbeck process in each family and suggests only moderate and lineage-specific effects of semantics on syntax, challenging the universality of the Interclausal Relations Hierarchy. Furthermore, geographic proximity exerts only minimal effects, consistent with the notion that the syntax-semantics interface may be more resistant to contact effects than overtly signaled and transparent patterns in language. Together, our findings suggest that the syntax-semantics interface is less constrained in clause linkage than is commonly assumed in typology. They furthermore highlight the value of treating phylogeny as a dynamic evolutionary process, rather than as a static background structure.

evolutionary biology↗

bioRxiv2024

An inverse correlation between linguistic and genetic diversity

Human population history, as traced by our genome, has shaped the distribution of languages around the world. While case studies suggest that population history can also affect specific structures of languages, such as patterns in their sound systems and grammars, results are conflicting, and it remains unknown whether such effects hold globally. Here we show that, adjusting for geography, phylogeny, and environment, genetic diversity is inversely correlated with diversity in linguistic structures. Low genetic diversity (i.e. excess homozygosity) results from relative isolation, and this promotes diversification in language. High genetic diversity results from contact and migration, and this promotes homogenization in language. These effects are particularly pronounced in Asia and, under some conditions, also in a few other areas, suggesting sociocultural factors contributing to differences in how strongly isolation favors linguistic diversity and how strongly contact promotes linguistic homogenization. Our results suggest that present-day hotspots of linguistic diversity, which are characterized by relative isolation, may provide a privileged window on the dynamics of linguistic evolution as they are less affected by the vast demographic expansions, migrations, and extinctions that characterize the Neolithic age.

evolutionary biology↗

bioRxiv2024

Global patterns of genetic admixture reveal effects of language contact

When speakers of different languages are in contact, they often borrow features like sounds, words, or syntactic patterns from one language to the other, but the lack of historical data has hampered estimation of this effect at a global scale. We break out of this impasse by using genetic admixture as a proxy for population contact. We find that language pairs whose speaker populations underwent genetic admixture or that are located in the same geo-historical area share more features than others, suggesting borrowing. The effect varies strongly across features, partly following expectations from differences in lifelong learnability, partly responding to differences in social imbalances during contact. Additionally, we find that for some features, admixture decreases sharing. This likely reflects signals of divergence (schismogenesis) under contact.

evolutionary biology↗

bioRxiv2024

Animal acoustic communication maintains a universal optimum rhythm

Most animals interact with conspecifics through acoustic signals that are modulated in frequency and rhythm. While small animals vocalize at higher pitch than large ones due to the smaller size of their vocal apparatus, the rules governing vocalization rhythms throughout the animal kingdom remain unknown. Vocal rhythms serve as a natural information parser, and one possibility is that they are constrained by the neural rhythms of transmitter and receiver, known to be relatively conserved across species and independent of their size. In this study, we quantified acoustic rhythms across taxa and investigated their evolutionary history with regard to phylogeny and selective pressure. In 98 species from six classes, we tested the main factors likely to influence their communication rhythms: morphology, physiology, social complexity, mastication and detectability. Phylogenetic modeling did not confirm the influence of these species-specific factors, but rather point to a scenario where acoustic communication rhythms have been maintained around an optimum at around 3Hz in the biological (neuronal) delta range (1-4Hz) well before the mammals split. These results suggest that the rhythm of acoustic communication signals, unlike their pitch, has a universal neural determinant that has been conserved throughout evolution, allowing for intra- and cross-species signaling.

animal behavior and cognition↗

bioRxiv2024

Oldest attested languages in the Near East reveal deep transformations in the distribution of linguistic features

It is an unresolved question to what extent the current frequency distributions of linguistic features inform us about what is representative of the language faculty and does not instead result from historical contingencies. We probe this question by leveraging unique data from the oldest attested languages, those preserved through writing from up to 5,000 years ago in the Ancient Near East. We examine 70 grammatical features for which there is sufficient evidence in the available records. After controlling for relatedness we find robust deviations of two of the oldest languages, Hurrian and Sumerian from both the ancient languages and the modern distribution. The spatial and temporal placement of these two languages reveal a divergent distribution of features in the region in prehistory, suggesting massive transformations of the linguistic distributions in the past few millennia. This challenges inferences about general characteristics of language based on modern distributions.

evolutionary biology↗

bioRxiv2023

Primate origins of human event cognition

Human language relies on a rich cognitive machinery, partially shared with other animals. One key mechanism, decomposing events into causally-linked agent-patient roles, however, has remained elusive with no known animal equivalent. In humans, agent-patient relations in event cognition drive how languages are processed neurally and expressions structured syntactically. We compared visual event tracking between humans and great apes, using stimuli that would elicit causal processing in humans. After accounting for attention to background information, we found similar gaze patterns to agent-patient relations in all species, mostly alternating attention to agents and patients, presumably in order to learn the nature of the event, and occasionally privileging agents under specific conditions. Six-month-old infants, in contrast, did not follow agent-patient relations and attended mostly to background information. We conclude that event role tracking, a cognitive foundation of syntax, evolved long before language but requires time and experience to become ontogenetically available. Significance statementHuman adults and great apes, but not human infants, track natural events as agent-patient relations, a cognitive foundation for syntax.

animal behavior and cognition↗

bioRxiv2022

Saturated reconstruction of living brain tissue

Complex wiring between neurons underlies the information-processing network enabling all brain functions, including cognition and memory. For understanding how the network is structured, processes information, and changes over time, comprehensive visualization of the architecture of living brain tissue with its cellular and molecular components would open up major opportunities. However, electron microscopy (EM) provides nanometre-scale resolution required for full in-silico reconstruction1-5, yet is limited to fixed specimens and static representations. Light microscopy allows live observation, with super-resolution approaches6-12 facilitating nanoscale visualization, but comprehensive 3D-reconstruction of living brain tissue has been hindered by tissue photo-burden, photobleaching, insufficient 3D-resolution, and inadequate signal-to-noise ratio (SNR). Here we demonstrate saturated reconstruction of living brain tissue. We developed an integrated imaging and analysis technology, adapting stimulated emission depletion (STED) microscopy6,13 in extracellularly labelled tissue14 for high SNR and near-isotropic resolution. Centrally, a two-stage deep-learning approach leveraged previously obtained information on sample structure to drastically reduce photo-burden and enable automated volumetric reconstruction down to single synapse level. Live reconstruction provides unbiased analysis of tissue architecture across time in relation to functional activity and targeted activation, and contextual understanding of molecular labelling. This adoptable technology will facilitate novel insights into the dynamic functional architecture of living brain tissue.

neuroscience↗

bioRxiv2021

From collocations to call-ocations: using linguistic methods to quantify animal call combinations

Emerging data in a range of non-human animal species have highlighted a latent ability to combine certain pre-existing calls together into larger structures. Currently, however, there exists no objective quantification of call combinations. This is problematic because animal calls can co-occur with one another simply through chance alone. One common approach applied in language sciences to identify recurrent word combinations is collocation analysis. Through comparing the co-occurrence of two words with how each word combines with other words within a corpus, collocation analysis can highlight above chance, two-word combinations. Here, we demonstrate how this approach can also be applied to non-human animal communication systems by implementing it on a pseudo dataset. We argue collocation analysis represents a promising tool for identifying non-random, communicatively relevant call combinations in animals.

animal behavior and cognition↗

bioRxiv2021

Contact-tracing in cultural evolution: a Bayesian mixture model to detect geographic areas of language contact

When speakers of two or more languages interact, they are likely to influence each other: contact leaves traces in the linguistic record, which in turn can reveal geographic areas of past human interaction and migration. However the complex, multi-dimensional nature of contact has hindered the development of a rigorous methodology for detecting its traces. Specifically, other factors may contribute to similarities between languages. Inheritance (a property is passed from an ancestor to several descendant languages), and universal preference (a property is universally preferred), may both overshadow contact signals. How can we find geographic contact areas in language data, while accounting for the confounding effects of inheritance and universal preference? We present sBayes, an algorithm for Bayesian clustering in the presence of confounding effects. The algorithm learns which similarities in a set of features are better accounted for by confounders, and which are due to contact effects. Contact areas are free to take any shape or size, but an explicit geographic prior ensures their spatial coherence. We test the clustering method on simulated data and apply it in two case studies to reveal language contact in South America and the Balkans. Our results are supported by --mostly qualitative-- findings from previous studies. While we focus on the specific problem of language contact, the method can also be used to uncover other traces of shared history in cultural evolution, and more generally, to reveal latent spatial clusters in the presence of confounders.

evolutionary biology↗

bioRxiv2020

Can Bayesian phylogeography reconstruct migrations and expansions in human history?

Bayesian phylogeography aims to reconstruct migrations in evolutionary processes. This methodological framework has been used for the reconstruction of homelands and historical expansions of various language families, but its reliability for language diversification research has remained unclear. We contribute to this discussion with a simulation study where we distinguish two types of spatial processes: migration and expansion. By migration we denote long-distance movement of whole populations, leaving their previous habitat empty. Expansions are small-scale movements of speakers or inclusions of new speakers into the language community, cumulatively contributing to a gradual spread into new territories. We simulate migrations, in the form of directional random walks, and expansions, in the form of a grid-based region-growing process. We run both simulation scenarios with varying degrees of directional trends and evaluate the performance of state-of-the-art phylogeographic methods. Our results show that phylogeography fails to reconstruct migrations, but works surprisingly well on expansions, even under severe directional trends. We demonstrate that migrations and expansions have typical phylogenetic and spatial patterns, which in the one case inhibit and in the other facilitate phylogeographic reconstruction. Furthermore, we propose descriptive statistics to identify whether a real sample of languages (Bantu), their relationship and spatial distribution, better fits a migration or an expansion scenario. Bringing together the results of the simulation study and theoretical arguments, we make recommendations for judging the adequacy of phylogeographic models to reconstruct the spatial evolution of languages.

evolutionary biology↗

bioRxiv2020

Languages, evolution and statistics: human sound systems were shaped by changes in bite configuration. Response to Tarasov & Uyeda (2020)

In Blasi et al. (2019) we have shown, through a series of statistical analyses and models, that human sound systems have been affected by a transition in bite configuration starting from the Neolithic. Tarasov and Uyeda (2020) (henceforth T&U) raise a number of observations in relation to our article. We appreciate T&Us engagement with our work and their sharing of the code and data of the analyses reported. In brief, their technical comment involves five analyses: O_LIBinomial Causal Models (BCM) C_LIO_LILinear Regression of across-area variation in labiodentals and subsistence C_LIO_LIPredictive Posterior Simulations (PPS) C_LIO_LIPoisson Linear Regression (PLR): model comparison C_LIO_LIPhylogenetic Analyses C_LI In what follows, we show that the discrepancies they report between our findings and theirs are due mostly to ill-specified models, weak (or missing) statistical evidence, and a misinterpretation of our results. After these issues are addressed, we conclude that T&Us claims do not hold.

evolutionary biology↗

bioRxiv2019

Exploring deep-time relationships between cultural and genetic evolution in Northeast Asia

Culture evolves in ways that are analogous to, but distinct from, genomes. Previous studies examined similarities between cultural variation and genetic variation (population history) at small scales within language families, but few studies empirically investigated such parallels across language families using diverse cultural data. We report an analysis comparing culture and genomes from in and around Northeast Asia spanning 11 language families. We extract and summarize the variation in language (grammar, phonology, lexicon), music (song structure, performance style), and genomes (genome-wide SNPs) and test for correlations. We find that grammatical structure correlates with population history. Recent contact and shared descent fail to explain the signal, suggesting relationships that arose before the formation of current families. Our results suggest that grammar might be a cultural indicator of population history, while also demonstrating differences among cultural and genetic relationships that highlight the complex nature of human history.

evolutionary biology↗