Experimental approach to the coevolution of language/cognition and Palaeolithic stone tool production

This paper reviews in short the current research on the hypothesis of coevolution between Palaeolithic stone tool manufacture on one side, and cognition and specifically language on the other. Of particular interest are behavioral and neuroimaging studies.

Experimental data suggesting a co-evolutionary relationship between Palaeolithic stone toolmaking, and cognition and language remain limited to indirect findings of neurophysiological studies. Furthermore, retouch and quartz flaking remain uninvestigated. We recruited thirteen subjects and taught them to produce quartz choppers and chert sidescrapers in either a verbal or gestural condition. Two raters rated on a 5-point scale the subjects’ performances on specific steps of the two stone toolmaking tasks. Subjects also performed on a neuropsychological battery encompassing visuospatial, executive functioning, and linguistic tasks. Given the small sample size, the results should be regarded as exploratory and preliminary. There was only limited evidence that verbal compared to gestural teaching facilitated acquisition. Quartz chopper manufacture was not associated with cognitive performance. Conversely, chert flaking and retouch were moderately and strongly associated with visuospatial working memory and executive functioning. Specific aspects of chert flaking were also associated with verbal fluency performance, showing, among others, moderate and strong positive associations with the productivity and rate of production of syntactically transitive verbs on action fluency. Controversially assuming similar results would have been obtained by testing extinct hominins, our results possibly suggest Oldowan hominins relied on modern-like visuospatial working memory and executive functioning during chert knapping. Furthermore, some prerequisites for aspects of action language and syntactic transitivity in modern humans might have been to some degree present in Oldowan hominin populations. We conclude by proposing that the quality of performance on Oldowan knapping may not reflect the full level of cognitive capacities of Oldowan populations.

This manuscript was published in the journal Društvena istraživanja: Journal for General Social Issues 28(2):361–362 and is available online (https://hrcak.srce.hr/220936) with the following DOI: https://doi.org/10.5559/di.28.2.11 .................................................................................................................................................. PLEASE CITE AS: Gabrić, P. (2019). Konferencija: Cognitive Science. Društvena istraživanja: Journal for General Social Issues, 28(2), 361–362. https://doi.org/10.5559/di.28.2.11 .................................................................................................................................................. Konferencija "Cognitive Science" održala se na Institutu "Jožef Stefan" u Ljubljani 11. listopada 2018. u sklopu 21. Međunarodne multikonferencije "Information Society". Konferenciju "Cognitive Science" organiziralo je Slovensko društvo za kognitivnu znanost. Cilj konferencije bio je povezati stručnjake iz raznih disciplina koje se bave kognicijom te omogućiti razmjenu raznolikih i izazovnih ideja.

Konferencija "Cognitive Science" održala se na Institutu "Jožef Stefan" u Ljubljani 11. listopada 2018. u sklopu 21. Međunarodne multikonferencije "Information Society". Konferenciju "Cognitive Science" organiziralo je Slovensko društvo za kognitivnu znanost. Cilj konferencije bio je povezati stručnjake iz raznih disciplina koje se bave kognicijom te omogućiti razmjenu raznolikih i izazovnih ideja.

U ovom ćemo radu predstaviti studentski istraživački projekt „Eksperimentalni pristup koevoluciji jezika i kamenog oruđa“ u kojem smo istraživali vezu između izrade dvaju tipova paleolitičkog kamenog oruđa te evolucije uma i specifično jezika. O evoluciji uma i jezika dugo se u velikom dijelu tog područja raspravljalo samo u okvirima antropologije i arheologije. Međutim, u novije doba u te su se rasprave uključile i lingvistika, psihologija i neuroznanost. Jedna od istaknutih teorija jest tzv. tehnološka hipoteza koja pretpostavlja koevolucijsku vezu između paleolitičkog kamenog oruđa i jezika. S jedne strane, tehnološku hipotezu podupiru studije koje pokazuju uključenost određenih moždanih područja poput Brocinog područja i ventralnog premotoričkog korteksa tijekom izrade određenih tipova kamenog oruđa, pri čemu se ta ista područja na ovaj ili onaj način povezuju i s jezičnim funkcijama u mozgu. S druge strane, studije koje istražuju učinke pojedinih tipova prenošenja znanja na usvajanje izrade kamenog oruđa pokazuju da jezične upute ne facilitiraju usvajanje izrade. U našem projektu 13 je ispitanika bez prethodnog znanja izrade kamenog oruđa učilo izrađivati oldovanski sjekač i, uvjetno rečeno, musterijensko strugalo. Ispitanici su bili podijeljeni u verbalnu, u kojoj su od demonstratora dobili jezične upute, i neverbalnu skupinu, u kojoj je demonstrator podučavao s pomoću gesti. Ispitanici su riješili i bateriju neuropsiholoških testova u programu PEBL kojima su se testirali vizualna pažnja, vizuospacijalna obrada, planiranje, kognitivna fleksibilnost i jezična obrada. Rezultati preliminarno pokazuju da izrada strugala koje se načelno veže uz neandertalce zahtijeva veći vizuospacijalni i izvršni kapacitet u usporedbi s izradom sjekača, koje se uglavnom veže uz Homo habilisa i eventualno australopitecine. Rezultati ne pokazuju jasno postoje li razlike u usvajanju između verbalne i neverbalne skupine u obama zadacima. Preliminarni rezultati slažu se s dosadašnjim istraživanjima koja sugeriraju da su se pojavom ašelejena i/ili specifično Homo erectusa pojavile i kognitivne sposobnosti bliske onima današnjeg Homo sapiensa, a koje potencijalno uključuju i komunikacijske sposobnosti koje podsjećaju na jezik. Projekt je financiran iz sredstava Odsjeka za arheologiju i Odsjeka za lingvistiku Filozofskog fakulteta Sveučilišta u Zagrebu. Voditelj projekta bio je Petar Gabrić. Suradnici na projektu bili su Marko Banda, prof. dr. sc. Ivor Karavanić i Luka Bulian.

Recently, considerable interest for language evolution has arisen. Many researchers believe that language evolved via exaptation of domain-general cognitive systems such as long-term memory, visuospatial processing and executive functioning. Therefore, many studies on language evolution have focused on determining when specific cognitive functions, which might have supported language, developed. One approach in this area has been to establish the neurocognitive and neural correlates of specific behaviours during the Palaeolithic period (from ~3.3 mya to ~10 kya). The focus has been on stone-toolmaking-related behaviours because of the higher preservation of stone in the archaeological record compared to other materials. The earliest stone industry is the pre-Homo Lomekwian. It has been hypothesized based on experimental replication of the knapping process that the Lomekwian findings are suggestive of lesser functional lateralization of the motoric and prefrontal cortex compared to modern humans. The next stone industry – the Oldowan –, typically associated with Homo habilis, has been linked to more complex subsistence strategies and social behaviours. Neuroimaging studies have shown that Oldowan toolmaking predominantly involves frontoparietal sensorimotor areas and the cerebellum, which is why this industry has been described as cognitively relatively „ape-like“. The following industry, the Acheulean, taxonomically linked to Homo erectus and chronologically coinciding with significant brain enlargements in our genus, is believed to be more demanding in hierarchical and sequential action processing compared to earlier technologies. Additionally, neuroimaging studies have shown higher activation of the right Broca's area and temporal cortici during Acheulean compared to Oldowan toolmaking. Recently, a study by our lab comparing sidescraper manufacture, associated with Homo heidelbergensis and Neanderthals, and Oldowan toolmaking has found higher involvement of visuospatial and executive functions in the former task. While it is hard to generalize based on this data, we will suggest some implications for the existence of language in early Homo.

Evolucija uma, a specifično jezika tema je koja u posljednje vrijeme privlači sve veću pažnju u naučnoj zajednici. O toj se temi donedavna raspravljalo uglavnom u antropološkim i arheološkim krugovima, a zbog pretpostavljene koevolucijske veze između uma i jezika s jedne strane te prastarog kamenog oruđa s druge. Novija su saznanja iz psihologije, neuroznanosti i lingvistike doprinijela teorijskom i metodološkom širenju područja evolucije uma. Dosadašnje su studije unutar tog teorijsko-metodološkog okvira istraživale, generalno rečeno, (1) učinak pojedinih oblika prenošenja znanja na usvajanje izrade pojedinih tipova kamenog oruđa te (2) neurofiziologiju usvajanja, izrade i promatranja izrade kamenog oruđa. Rezultati tih studija daju općenito za zaključiti da uporaba gesta pospješuje usvajanje izrade oruđa, no ne i uporaba jezika. Iako je teško generalizirati na temelju tih rezultata, predlažemo neke implikacije koje bi oni mogli imati za postojanje jezika u arhaičnim vrstama hominina.

Many authors suggest that there is a co-evolutionary relationship between Palaeolithic stone toolmaking and language. This assumption is, firstly, supported by experimental studies showing positive effects of verbal compared to non-verbal demonstration during stone toolmaking acquisition in present-day humans. Secondly, it is backed by neurophysiological studies which demonstrate that both toolmaking and language activate overlapping brain regions and that they exhibit similar hemodynamic lateralization patterns in present-day humans. These studies have mainly been focused on Oldowan flaking and Acheulean handaxe manufacture. Studies on the effects of the verbal and non-verbal transmission modes currently suggest that both Oldowan and Acheulean acquisition are facilitated by non-linguistic gestures rather than purely spoken language. Furthermore, neuroimaging studies have found that the prefrontal cortex, an area typically associated with executive functioning, and the temporal cortex are activated more during Acheulean compared to Oldowan tasks. We recruited twelve Croatian-speaking subjects with no prior experience in knapping. Subjects were taught the Oldowan chopper and Mousterian sidescraper manufacture in a verbal teaching and non-verbal basic teaching condition. Tool quality was assessed by measurements of various physical attributes and a subjective evaluation by two assessors on a 5-point scale. Subjects were also tested on a neuropsychological battery assessing visual attention, verbal working memory, visuospatial processing, planning, cognitive flexibility, general executive functioning and lexical-semantic processing. We hypothesize that there will be no significant differences between the verbal and non-verbal groups in the chopper manufacture task, and that the verbal group will perform significantly better compared to the non-verbal group in the sidescraper manufacture task. Additionally, we hypothesize that chopper manufacture will be significantly positively correlated only with the visual processing tasks, while sidescraper manufacture will also be significantly positively correlated with the prefrontal functioning tasks. The obtained results will be interpreted within the framework of current evolutionary and cognitive theories.

This paper reviews in short the current research on the hypothesis of coevolution between Palaeolithic stone tool manufacture on one side, and cognition and specifically language on the other. Of particular interest are behavioral and neuroimaging studies.