Laboratoire Dynamique du Langage

This paper presents an overview of a state-of-the-art text-independent speaker verification system. First, an introduction proposes a modular scheme of the training and test phases of a speaker verification system. Then, the most commonly speech parameterization used in speaker verification, namely, cepstral analysis, is detailed. Gaussian mixture modeling, which is the speaker modeling technique used in most systems, is then explained. A few speaker modeling alternatives, namely, neural networks and support vector machines, are mentioned. Normalization of scores is then explained, as this is a very important step to deal with real-world data. The evaluation of a speaker verification system is then detailed, and the detection error trade-off (DET) curve is explained. Several extensions of speaker verification are then enumerated, including speaker tracking and segmentation by speakers. Then, some applications of speaker verification are proposed, including on-site applications, remote applications, applications relative to structuring audio information, and games. Issues concerning the forensic area are then recalled, as we believe it is very important to inform people about the actual performance and limitations of speaker verification systems. This paper concludes by giving a few research trends in speaker verification for the next couple of years.

Single words and sentences referring to bodily actions activate the motor cortex. However, this semantic grounding of concrete language does not address the critical question whether the sensory-motor system contributes to the processing of abstract meaning and thought. We examined functional magnetic resonance imaging activation to idioms and literal sentences including arm- and leg-related action words. A common left fronto-temporal network was engaged in sentence reading, with idioms yielding relatively stronger activity in (pre)frontal and middle temporal cortex. Crucially, somatotopic activation along the motor strip, in central and precentral cortex, was elicited by idiomatic and literal sentences, reflecting the body part reference of the words embedded in the sentences. Semantic somatotopy was most pronounced after sentence ending, thus reflecting sentence-level processing rather than that of single words. These results indicate that semantic representations grounded in the sensory-motor system play a role in the composition of sentence-level meaning, even in the case of idioms.

We test the hypothesis that motivational and cognitive processes are linked by a specific neural system to reach maximal efficiency. We studied six normal subjects performing a working memory paradigm (n-back tasks) associated with different levels of monetary reward during an fMRI session. The study showed specific brain activation in relation with changes in both the cognitive loading and the reward associated with task performance. First, the working memory tasks activated a network including the dorsolateral prefrontal cortex [Brodmann area (BA) 9/46] and, in addition, in the lateral frontopolar areas (BA 10), but only in the more demanding condition (3-back task). This result suggests that lateral prefrontal areas are organized in a caudo-rostral continuum in relation with the increase in executive requirement. Second, reward induces an increased activation in the areas already activated by working memory processing and in a supplementary region, the medial frontal pole (BA 10), regardless of the level of cognitive processing. It is postulated that the latter region plays a specific role in monitoring the reward value of ongoing cognitive processes. Third, we detected areas where the signal decreases (ventral-BA 11/47 and subgenual prefrontal cortices) in relation with both the increase of cognitive demand and the reward. The deactivation may represent an emotional gating aimed at inhibiting adverse emotional signals to maximize the level of performance. Taken together, these results suggest a balance between increasing activity in cortical cognitive areas and decreasing activity in the limbic and paralimbic structures during ongoing higher cognitive processing.

A recently emerging view sees language understanding as closely linked to sensory and motor processes. The present study investigates this issue by examining the influence of processing action verbs and concrete nouns on the execution of a reaching movement. Fine-grained analyses of movement kinematics revealed that relative to nouns, processing action verbs significantly affects overt motor performance. Within 200 msec after onset, processing action verbs interferes with a concurrent reaching movement. By contrast, the same words assist reaching movement when processed before movement onset. The cross-talk between language processes and overt motor behavior provides unambiguous evidence that action words and motor action share common cortical representations and could thus suggest that cortical motor regions are indeed involved in action word retrieval.

Frontotemporal dementia (FTD), characterized by behavioural and language disorders, is a clinically, genetically and pathologically heterogeneous group of diseases. The most recently identified of the four known genes is GRN, associated with 17q-linked FTD with ubiquitin-immunoreactive inclusions. GRN was analysed in 502 probands with frontal variant FTD (fvFTD), FTD with motoneuron disease (FTD-MND), primary progressive aphasia (PPA) and corticobasal degeneration syndrome (CBDS). We studied the clinical, neuropsychological and brain perfusion characteristics of mutation carriers. Eighteen mutations, seven novel were found in 24 families including 32 symptomatic mutation carriers. No copy number variation was found. The phenotypes associated with GRN mutations vary greatly: 20/32 (63%) carriers had fvFTD, the other (12/32, 37%) had clinical diagnoses of PPA, CBDS, Lewy body dementia or Alzheimer's disease. Parkinsonism developed in 13/32 (41%), visual hallucinations in 8/32 (25%) and motor apraxia in 5/21 (24%). Constructional disorders were present in 10/21 (48%). Episodic memory disorders were frequent (16/18, 89%), consistent with hippocampal amnestic syndrome in 5/18 (28%). Hypoperfusion was observed in the hippocampus, parietal lobe and posterior cingulate gyrus, as well as the frontotemporal cortices. The frequency of mutations according to phenotype was 5.7% (20/352) in fvFTD, 17.9% (19/106) in familial forms, 4.4% in PPA (3/68), 3.3% in CBDS (1/30). Hallucinations, apraxia and amnestic syndrome may help differentiate GRN mutation carriers from others FTD patients. Variable phenotypes and neuropsychological profiles, as well as brain perfusion profiles associated with GRN mutations may reflect different patterns of neurodegeneration. Since all the mutations cause a progranulin haploinsufficiency, additional factors probably explain the variable clinical presentation of the disease.

In present-day knowledge societies, competent reading involves the integration of information from multiple sources into a coherent, meaningful representation of a topic, issue, or situation. This article reviews research and theory concerning the comprehension of multiple textual resources, focusing especially on linkages recently established between dimensions of epistemic beliefs and multiple-text comprehension. Moreover, a proposed model incorporates epistemic beliefs into a theoretical framework for explaining multiple-text comprehension, specifying how and why different epistemic belief dimensions may be linked to the comprehension and integration of multiple texts. Also discussed is the need for further research concerning mediational mechanisms, causality, and generalizability.

The history of southern Africa involved interactions between indigenous hunter-gatherers and a range of populations that moved into the region. Here we use genome-wide genetic data to show that there are at least two admixture events in the history of Khoisan populations (southern African hunter-gatherers and pastoralists who speak non-Bantu languages with click consonants). One involved populations related to Niger-Congo-speaking African populations, and the other introduced ancestry most closely related to west Eurasian (European or Middle Eastern) populations. We date this latter admixture event to ∼900-1,800 y ago and show that it had the largest demographic impact in Khoisan populations that speak Khoe-Kwadi languages. A similar signal of west Eurasian ancestry is present throughout eastern Africa. In particular, we also find evidence for two admixture events in the history of Kenyan, Tanzanian, and Ethiopian populations, the earlier of which involved populations related to west Eurasians and which we date to ∼2,700-3,300 y ago. We reconstruct the allele frequencies of the putative west Eurasian population in eastern Africa and show that this population is a good proxy for the west Eurasian ancestry in southern Africa. The most parsimonious explanation for these findings is that west Eurasian ancestry entered southern Africa indirectly through eastern Africa.

Three experiments, using the high-amplitude sucking procedure, tested whether 4-day-old infants discriminate multisyllabic utterances on the basis of number of syllables or number of phonemes. Experiment 1 showed that infants discriminate 2 large sets of phonetically variable utterances composed of 2- vs. 3-CV (consonant-vowel) syllables. Experiment 2 was run to assess whether infants discriminated the 2 sets on the basis of duration differences between the 2- and 3-CV stimuli. Results indicate that reducing the duration differences does not affect infants'discrimination. Finally, Experiment 3 investigated whether infants discriminate 4- vs. 6-phoneme bisyllabic utterances. The results provide no evidence that infants are sensitive to such a change in number of phonemic constituents

Keyphrase extraction is the task of iden-tifying single or multi-word expressions that represent the main topics of a doc-ument. In this paper we present Topi-cRank, a graph-based keyphrase extrac-tion method that relies on a topical rep-resentation of the document. Candidate keyphrases are clustered into topics and used as vertices in a complete graph. A graph-based ranking model is applied to assign a significance score to each topic. Keyphrases are then generated by select-ing a candidate from each of the top-ranked topics. We conducted experiments on four evaluation datasets of different languages and domains. Results show that TopicRank significantly outperforms state-of-the-art methods on three datasets. 1

loci. Finally, we identified a major contribution of western central African Bantu speakers to the ancestry of African Americans, whose genomes present no strong signals of natural selection. Together, these results highlight the contribution of Bantu-speaking peoples to the complex genetic history of Africans and African Americans.

The first fricatives In 1985, the linguist Charles Hockett proposed that the use of teeth and jaws as tools in hunter-gatherer populations makes consonants produced with lower lip and upper teeth (“f” and “v” sounds) hard to produce. He thus conjectured that these sounds were a recent innovation in human language. Blasi et al. combined paleoanthropology, speech sciences, historical linguistics, and methods from evolutionary biology to provide evidence for a Neolithic global change in the sound systems of the world's languages. Spoken languages have thus been shaped by changes in the human bite configuration owing to changes in dietary and behavioral practices since the Neolithic. Science , this issue p. eaav3218

Summary: : Five children with Landau‐Kleffner syndrome (epilepsy, acquired aphasia, and continuous spike‐wave discharges during sleep), were treated with antiepileptic drugs (AEDs), sleep‐modifying drugs, and corticosteroids. The pharmacologic profiles differed from those observed in focal epilepsies, resembling instead those of certain generalized epilepsies, such as West or Lennox‐Gastaut syndromes. Phenobarbital (PB), carbamazepine (CBZ), and phenytoin (PHT) were ineffective or worsened the EEG and neuropsychological symptoms, whereas valproate (VPA), ethosuximide (ESM), and benzodiazepines were partially or transiently efficacious. Dextroamphetamine produced a dramatic but transient improvement in waking and sleep EEG in one of two children; aphasia did not change. Corticosteroid treatment resulted in improved speech, suppression of seizures, and normalization of the EEG in three of three children. Our own experience and data from the literature suggest that corticosteroids should be given in high doses as soon as the diagnosis is firmly established and should be continued in maintenance dose for several months or years to avoid escape. Early diagnosis, before mutism or global deterioration develops, appears to be essential for effective therapy with minimal neuropsychological sequelae. RÉSUMÉ Cinq enfants présentant un syndrome de Landau‐Kleffner (épilepsie, aphasie acquise et pointes‐ondes continues pendant le sommeil) ont été traités par médicaments antiépileptiques, mo‐dificateurs du sommeil et corticoïdes. Les profils pharma‐cologiques constatés different de ceux des épilepsies focales et sont plus proches de ceux de certaines épilepsies généralisées, comme les syndromes de West et de Lennox‐Gastaut. Le phénobarbital, la carbamazépine et la phénytoine se sont révélés inefficaces ou aggravants sur la plan EEG et neuropsy‐chologique, alors que le valproate, l'éthosuximide et les benzodiazépines ont été partiellement ou transitoirement efficaces. La dextroamphétamine a entraîné une amélioration franche mais transitoire de l'EEG de veille et de sommeil chez l'un de 2 en‐fants; il n'y a pas eu de modification de l'aphasie. Le traitement par corticoïdes a entraîné une amélioration du langage, la suppression des crises et la normalisation de l'EEG chez 3 enfants sur 3. L'éxperience des auteurs et les donéees de la littérature suggerent que les corticoides doivent étre données e fortes doses des que le diagnostic est confirmé et doivent être poursuivis à une dose d'entretien pendant plusieurs mois ou années afin d'‐éviter un échappement thérapeutique. Un diagnostic precoce, porté avant l'installation d'un mutisme ou d'une détérioration globale, semble essentiel pour garantir un traitement efficace et un minimum de séqeulles neuropsychologiques. RESUMEN Cinco niños con síndrome de Landau‐Kleffner (epilepsyía, afasia adquirida y descargas punta‐onda continuas durante el sueño) han sido tratados con medicaciones antiepliépticas, drogas que alteran el sueño y corticoesteroides. Los perfiles farmacológicos se diferenciaron de los que se observan habitualmente en epilepsias focales y se parec íaan más a los de ciertas epilepsyías gene‐ralizadas como puede ser el síndrome de West o de Lennox‐Gastaut. El Fenobarbital, la Carbamacepina y la Fenitoína fueron ineficaces o empeoraron el EEG y los sfntomas neuro‐psicológicos mientras que el Valproato, la Etosuximida y las Benzodiazepinas fueron parcialmente o transitoriamente eficaces. La Dextroanfetamina produjó una mejorfa dramática pero transitoria del EEG en vigilia y de sueño en 1 de 2 ninos; la afasia nose modificó. El tratamiento con corticoesteroides resultó en una majoría del lenguaje, una supresión de los ataques y una normalización del EEG en 3 de 3 enfermos. La experiencia de los autores y la que consta en la literatura sugieren que los corticoesteroides deben ser administrados en altas dosis tan pronto como el diagnóstico se establece firmemente y debe ser continuado, con dosis de mantenimiento, durante varios meses o años para evitar las recaídas. Un diagnóstico precoz, antes del mu‐tismo o del deterioro global, es esencial para que la terapia sea eficaz con mínimas secuelas neuropsicológicas. ZUSAMMENFASSUNG Fünf Kinder mit einem L‐K‐S (Epilepsie, erworbene Aphasie und kontinuierliche Spike‐wave‐Entladungen im Schlaf) wurden mit Antiepileptika, schlafverändemden Medikamenten und Kor‐tikosteroiden behandelt. Die pharmakologischen Profile unter‐schieden sich von solchen bei Herdepilepsien und glichen eher denjenigen generalisierter Epilepsien wie West‐ oder Lennox‐Gastaut‐Syndrom. PhB, CBZ und PHT waren wirkungslos oder verschlechterten das EEG, während VALP, ESUX und Benzodiazepine teilweise oder zeitweilig wirksam waren. Dextroam‐phetamin brachte eine dramatische aber nur vorubergehende Besserung der Wach‐ und Schlaf‐EEG's bei einem von zwei Kindern. Die Aphasie änderte sich nicht. Kortikoide verbes‐serten die Sprache, unterdrückten die Anfälle und nonnalisierten bei drei von 3 Kindern das EEG. Unsere eigenen und die Ergeb‐nisse der Literatur sprechen für eine hochdosierte Kortikoidgabe, sobald die Diagnose gestellt ist. Diese Medikation sollte für einige Monate oder Jahre in einer Erhaltungsdosis wei‐tergegeben werden. Ein fruher Beginn vor Einsetzen des Mutis‐mus oder allgemeinem Abbau scheint unabdingbar für eine wirk‐same Therapie mit geringen neurologischen Nebenwirkungen zu sein.

Summary: : In five children with normal initial psychomotor development, a Landau‐Kleffner syndrome appeared at age 3–7 years. No neuroanatomy; lesions were noted. Aphasia and hyperkinesia were isolated in three patients and associated with global regression of higher cortical functions in one patient. Massive intellectual deterioration and psychotic behavior were associated with transient aphasia in one patient. The epilepsy (focal motor and generalized tonic‐clonic seizures, subclinical EEG focal seizures during sleep, and atypical absences) always regressed spontaneously or with antiepileptic drug (AED) treatment. The EEG in waking patients snowed focal and generalized spike‐wave discharges on a normal background rhythm. Discharge topography and pattern changed frequently. During sleep, discharges always increased. At some time during syndrome development, all patients had bilateral spike‐waves for 7gt;85% of the sleep period, while at other times the discharges were discontinuous or continuous but focal or unilaterally hemispheric. Discharge topography and abundance changed from night to night. The abnormal EEG and the impaired higher functions developed and regressed together, but not with strict temporal correlation. Our own experience suggests that the Landau‐Kleffner syndrome and epilepsy with continuous spike‐wave activity in slow‐wave sleep cannot be clearly differentiated. They may be different points on the spectrum of a single syndrome. RÉSUMÉ Les auteurs rapportent 5 observations d'un syndrome de Landau‐Kleffner ayant débuté entre 3 et 7 ans chez des enfants qui avaient présenté un développement psychomoteur normal. Us n'ont pas trouvé de lésion neuroanatomique. L'aphasie et l'hyperkinésie étaient les seuls symptômes chez 3 patients, ils étaient associés à une régression globale des fonctions su‐périeures chez 1 cas, le dernier cas présentant une détérioration intellectuelle massive et un comportement psychotique avec aphasie transitoire. L'épilepsie (crises partielles et crises généralisées tonico‐cloniques, crises focales infracliniques pendant le sommeil et absences atypiques) a toujours régressé spon‐tanément ou sous traitement antiépileptique. A la veille, l'EEG des déscharges de pointes‐ondes focales et généralisées sur une activité de fond normale. La topographie et l'aspect des PO changeait fréquemment. Pendant le sommeil, des déscharges étaient toujours activeées. A un moment donné de revolution, tous les patients ont présenté des PO bilatérales pendant plus de 85% de la période de sommeil, alors qu'à d'autre s moments les decharges etaient discontinues, ou continues mais focales ou uni‐laterales. La topographie et l'abondance des décharges étaient variable d'une nuit à l'autre. Les anomalies EEG et neuropsy‐chologiques ont évolué de façon paralléle, mais sans relation temporelle stride. Les auteurs pensent que le syndrome de Landau‐Kleffner et le syndrome des pointes‐ondes continues pendant le somm eil lent ne sont guére différents et représententvraisemblablement deux expressions du spectre d'un seul et unique syndrome. RESUMEN En 5 niños con desarrollo initial psicomotor normal se observó la aparición de un síndrome de Landau‐Kleffner entre los 3 y los 7 años de edad. No aparecieron lesiones neuroanatómicas. La afasia y la hiperkinesia fueron los únicos st'ntomas en 3 enfermos y se asociaron a regresión global de las funciones corticales su‐periores en un enfermo. El deterior masivo intelectual y un com‐portamiento psic6tico aparecid asociado a afasia transitoria en un enfermo. La epilepsyía (focal motora y crisis tónico‐clónicas generalizadas, crisis focales subcífnicas en el EEG durante el sueño y ausencias atípicas) siempre regresó espontáneamente o con medicaciones antiepilépticas. El EEG en enfermos despier‐tos mostró descargas punta‐onda focales y generalizadas sobre una actividad de fondo normal. La distributeón topográfica y el partón de las descargas cambiaron frecuentemente. Durante el sueño, las descargas siempre se incrementaron. En algunos mo‐mentos durante el desarrollo del síndrome clínico, todos los pa‐cientes presentaron descargas punta‐onda bilaterales durante más del 85% del perfodo de sueño mientras, en otros momentos, las descargas fueron discontinuas o continuas pero con latera‐lización hemisférica o focalidad. La topografia de las descargas y su número cambiaron de la noche al día. El EEG anormal y la afectación de funciones cerebrates superiores se desarrollaban y también regresaban conjunctamente, pero sin que existiera una correlación temporal estricta. Según la experiencia de los au‐tores el síndrome de Landau‐Kleffner y la epilepsia con actividad punta‐onda continua durante la fase de sueño lento no pueden diferenciarse con claridad. Pueden representar puntos distintos en un común espectro de un síndrome único. ZUSAMMENFASSUNG 5 Kinder mit anfänglicher Normalentwicklung boten im Alter zwischen 3 und 7 Jahren ein LKS. Eine neuroanatomische Lae‐sion konnte nicht gefunden werden. Aphasie und Hyperkinesen traten bei 3 Patienten isoliert auf und bei 1 Patienten mit allge‐meiner Regression der höheren Funktionen. Massiver intellek‐tueller Abbau und psychotisches Verhalten waren bei vorüber‐gehender Aphasie bei 1 Patienten zu beobachten. Die Epilepsie (fokal motorische und größe Anfälle, subklinische Anfalle im Schlaf‐EEG und atypische Absencen) ging spontan zurück oder sprach gut auf Antiepileptika an. Das Wach‐EEG zeigte fokale und generalisierte spike‐wave‐Entladungen bei normaler Grun‐daktivität. Entladungsmuster und ‐Ort wechselten häufig. Während des Schlafs nahmen die Entladungen stets zu. Zu einem bestimmten Zeitpunkt, während der Entwicklung des Syndroms, boten alle Patienten generalisierte spike waves in mehr als 85% des Schlafs. Zu einem späteren Zeitpunkt waren die Entladungen diskontinuierlich oder kontinuierlich aber fokal oder unilateral. Die Entladungstopographie und das Ausmaßänderten sich von Nacht zu Nacht. Abnormes EEG und Verschlechterung der höheren kortikalen Funktionen traten gemeinsam auf und gingen auch wieder zurük, jedoch nicht mit eindeutiger zeitlicher Übereinstimmung. Unsere Erfahrungen zeigen, daß das LKS und die Epilepsie mit kontinuierlicher spike‐wave‐Aktivität im langsamen Scblaf nicht genau differenziert werden kann. Ver‐mutlich gibt es unterschiedliche Ausprägungen der Symptome bei den einzelnen Patienten.

This paper describes a distinctive system of nominal subclasses observed in Dalabon, a non-Pama-Nyungan, Gunwinyguan language of south-western Arnhem Land, Australia. These subclasses differ from what is usually called ‘noun classes’ in Australian languages, and no such system has been described for an Australian language so far. While most Gunwinyguan languages use noun class prefixes offering an overt categorization of noun classes, Dalabon has no such prefixes. On the other hand, six semantically coherent nominal subclasses can be delineated based on four inter-related criteria—noun incorporation, boundness, obligatory possession and possessor raising. These subclasses are animate-part nouns (incorporable, strictly bound, obligatorily possessed, raising their possessors freely), kin-terms (incorporable, strictly bound, obligatorily possessed, raising their possessor when incorporated), inanimate-part nouns (incorporable, strictly bound, not obligatorily possessed), features of the landscape (incorporable, semi-bound, not obligatorily possessed), natural-kind nouns (non-incorporable) and generic nouns (incorporable free nouns). Some of the subclasses qualify as more or less inalienable. Along the way, the article discusses various aspects of Dalabon grammar such as word classes, noun incorporation and possessive constructions. The nominal subclass divisions also shed light upon some the distribution and semantics of the ubiquitous -no suffix, which remained obscure hitherto.

Language is universal, but it has few indisputably universal characteristics, with cross-linguistic variation being the norm. For example, languages differ greatly in the number of syllables they allow, resulting in large variation in the Shannon information per syllable. Nevertheless, all natural languages allow their speakers to efficiently encode and transmit information. We show here, using quantitative methods on a large cross-linguistic corpus of 17 languages, that the coupling between language-level (information per syllable) and speaker-level (speech rate) properties results in languages encoding similar information rates (~39 bits/s) despite wide differences in each property individually: Languages are more similar in information rates than in Shannon information or speech rate. These findings highlight the intimate feedback loops between languages' structural properties and their speakers' neurocognition and biology under communicative pressures. Thus, language is the product of a multiscale communicative niche construction process at the intersection of biology, environment, and culture.

The transition from hunting and gathering to farming involved a major cultural innovation that has spread rapidly over most of the globe in the last ten millennia. In sub-Saharan Africa, hunter-gatherers have begun to shift toward an agriculture-based lifestyle over the last 5,000 years. Only a few populations still base their mode of subsistence on hunting and gathering. The Pygmies are considered to be the largest group of mobile hunter-gatherers of Africa. They dwell in equatorial rainforests and are characterized by their short mean stature. However, little is known about the chronology of the demographic events-size changes, population splits, and gene flow--ultimately giving rise to contemporary Pygmy (Western and Eastern) groups and neighboring agricultural populations. We studied the branching history of Pygmy hunter-gatherers and agricultural populations from Africa and estimated separation times and gene flow between these populations. We resequenced 24 independent noncoding regions across the genome, corresponding to a total of approximately 33 kb per individual, in 236 samples from seven Pygmy and five agricultural populations dispersed over the African continent. We used simulation-based inference to identify the historical model best fitting our data. The model identified included the early divergence of the ancestors of Pygmy hunter-gatherers and farming populations approximately 60,000 years ago, followed by a split of the Pygmies' ancestors into the Western and Eastern Pygmy groups approximately 20,000 years ago. Our findings increase knowledge of the history of the peopling of the African continent in a region lacking archaeological data. An appreciation of the demographic and adaptive history of African populations with different modes of subsistence should improve our understanding of the influence of human lifestyles on genome diversity.

Two groups of populations with completely different lifestyles-the Pygmy hunter-gatherers and the Bantu-speaking farmers-coexist in Central Africa. We investigated the origins of these two groups and the interactions between them, by analyzing mtDNA variation in 1,404 individuals from 20 farming populations and 9 Pygmy populations from Central Africa, with the aim of shedding light on one of the most fascinating cultural transitions in human evolution (the transition from hunting and gathering to agriculture). Our data indicate that this region was colonized gradually, with an initial L1c-rich ancestral population ultimately giving rise to current-day farmers, who display various L1c clades, and to Pygmies, in whom L1c1a is the only surviving clade. Detailed phylogenetic analysis of complete mtDNA sequences for L1c1a showed this clade to be autochthonous to Central Africa, with its most recent branches shared between farmers and Pygmies. Coalescence analyses revealed that these two groups arose through a complex evolutionary process characterized by (i) initial divergence of the ancestors of contemporary Pygmies from an ancestral Central African population no more than approximately 70,000 years ago, (ii) a period of isolation between the two groups, accounting for their phenotypic differences, (iii) long-standing asymmetric maternal gene flow from Pygmies to the ancestors of the farming populations, beginning no more than approximately 40,000 years ago and persisting until a few thousand years ago, and (iv) enrichment of the maternal gene pool of the ancestors of the farming populations by the arrival and/or subsequent demographic expansion of L0a, L2, and L3 carriers.

Sociocultural phenomena, such as exogamy or phylopatry, can largely determine human sex-specific demography. In Central Africa, diverging patterns of sex-specific genetic variation have been observed between mobile hunter-gatherer Pygmies and sedentary agricultural non-Pygmies. However, their sex-specific demography remains largely unknown. Using population genetics and approximate Bayesian computation approaches, we inferred male and female effective population sizes, sex-specific migration, and admixture rates in 23 Central African Pygmy and non-Pygmy populations, genotyped for autosomal, X-linked, Y-linked, and mitochondrial markers. We found much larger effective population sizes and migration rates among non-Pygmy populations than among Pygmies, in agreement with the recent expansions and migrations of non-Pygmies and, conversely, the isolation and stationary demography of Pygmy groups. We found larger effective sizes and migration rates for males than for females for Pygmies, and vice versa for non-Pygmies. Thus, although most Pygmy populations have patrilocal customs, their sex-specific genetic patterns resemble those of matrilocal populations. In fact, our results are consistent with a lower prevalence of polygyny and patrilocality in Pygmies compared with non-Pygmies and a potential female transmission of reproductive success in Pygmies. Finally, Pygmy populations showed variable admixture levels with the non-Pygmies, with often much larger introgression from male than from female lineages. Social discrimination against Pygmies triggering complex movements of spouses in intermarriages can explain these male-biased admixture patterns in a patrilocal context. We show how gender-related sociocultural phenomena can determine highly variable sex-specific demography among populations, and how population genetic approaches contrasting chromosomal types allow inferring detailed human sex-specific demographic history.

Over the last decades, scientists have questioned the origin of the exquisite human mastery of tools. Seminal studies in monkeys, healthy participants and brain-damaged patients have primarily focused on the plastic changes that tool-use induces on spatial representations. More recently, we focused on the modifications tool-use must exert on the sensorimotor system and highlighted plastic changes at the level of the body representation used by the brain to control our movements, i.e., the Body Schema. Evidence is emerging for tool-use to affect also more visually and conceptually based representations of the body, such as the Body Image. Here we offer a critical review of the way different tool-use paradigms have been, and should be, used to try disentangling the critical features that are responsible for tool incorporation into different body representations. We will conclude that tool-use may offer a very valuable means to investigate high-order body representations and their plasticity.

This chapter aims at presenting the various methods employed for classifying Bantu languages, paying particular attention to Guthrie’s classification, then to lexicostatistical works and briefly other more specific approaches, like Möhlig’s and Ehret’s, and finally moving to more recent phylogenetic methods using Bayesian inference, network representations, etc. It tries to give a balanced and objective account of the principles and results achieved by the studies under examination and presents them in a compact format.