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Co-Auteur(s): Lluís BARCELÓ-COBLIJN (Universitat de les Illes Balears, Spain) Cedric BOECKX (ICREA/Universitat de Barcelona, Spain)

Variation, speciation and the development of sapiens' language ready brain

Abstract/Résumé: In this talk we would like to consider the question of whether other hominins closely related to Homo sapiens had a linguistic system similar to ours. This will offer us an opportunity to reconsider the relation between genetics and the language faculty and try to explore an important issue: does having a particular set of gene(s) (e.g. FOXP2 or its interactome) imply having the Language Faculty? It is known that anatomically-modern humans (henceforth, AMH) have interbred with at least three different hominins. Does this fact imply that they also had modern language? We do not think so, and the reasons are related to natural laws and, we suggest, organic developmental patterns that can be found in nature. We claim that only AMH. had a full blown language system (though we have no problem claiming that other species could vocalize), and put forth the idea that differences accounting for this specific trait in AMH lie in developmental trajectories. This in turn leads us to call for a renewed interest in grounding theoretical claims (such as Universal Grammar) into facts about the brain. Here we rely on a specific model advanced by Boeckx (Boeckx, C. [2012] Homo combinans. Keynote talk, EVOLANG9, Kyoto), who takes the core structuring of human language syntax to be a clock-wavefront mechanism (part of a larger family of reaction-diffusion, or more accurately, Local Autoactivation Lateral Inhibition/LALI mechanisms), implemented in the brain in terms of a cortico-thalamic network (whose externalization is linked to Broca's region and the basal ganglia). The implication of the thalamus is especially significant in light of the attested sapiens-specific skull, and by hypothesis, brain globularity, achieved through development, as the position of the thalamus in a globular brain offers the possibility of more efficient connection and information exchange. We take this to be a special instance of a more general argument in favor of computational efficiency in the context of language. In sum, if AMH, Neanderthals, and Denisovans share a 99.5% of the genome, how can we argue in favor of differentiated cognitions? The answer largely lays in 1) the natural principles that regulate the brain growth and 2) the brain activity. Genetics has long provided arguments that two organisms can have the same genes and still show different ontogenic developments. We argue that – without preventing interbreeding– a differing developmental trajectory separated sapiens from Neanderthals, giving rise to distinct cognitive profiles. In other words, as Richard Lewontin would have it, even with having the genes, ‘it ain’t necessarily so’.