Handedness in Neandertals from the El Sidrón (Asturias, Spain): Evidence from Instrumental Striations with Ontogenetic Inferences

Abstract

The developed cognitive capabilities for Homo sapiens seems to be the result of a specialized and lateralized brain, and as a result of this, humans display the highest degree of manual specialization or handedness among the primates. Studies regarding its emergence and distribution within the genus Homo show that handedness is present very early. The mode in which it was articulated and spread across the different species during the course of human evolution could provide information about our own cognitive capacities. Here we report the manual laterality attributed to eleven 49,000 old Neandertal individuals from El Sidrón cave (Spain), through the study of instrumental or cultural striations on the anterior dentition. Our results show a predominant pattern addressed to right-handers. These results fit within the modern human handedness distribution pattern and provide indirect evidence for behavior and brain lateralization on Neandertals. They support the early establishment of handedness in our genus. Moreover, the individual identified as Juvenile 1 (6–8 years old at death), displays the same striation pattern as the adult Neandertals from the sample, and thereby the ontogenic development of manual laterality in that Neandertal population seems to be similar to that of living modern humans.

Evidence of toothpick groove formation in Neandertal anterior and posterior teeth

“…We noticed that the incidence of toothpick grooves was higher (eight of nine individuals) in Hortus individuals than in the El Sidrón individuals (nine of 11 individuals are affected). One of the explanations for the incidental differences between both groups could be that the El Sidrón sample consisted of individuals with low occlusal dental wear (Estalrrich & Rosas, ; Estalrrich et al, ; Rosas et al, ), while the individuals from Hortus have an advanced occlusal wear in average (de Lumley, ) (see also Table ). As the experimental replications of toothpick grooves have proved before (Bouchneb & Maureille, ; Hlusko, ), and our study does now, the formation of a groove is a cumulative process that requires time.…”

“…From these individuals, sex identification remains unknown. High‐resolution replicas of the Hortus teeth were made following established procedures (Estalrrich & Rosas, ; Teaford & Oyen, ). Hydrophilic vinyl polysiloxane impression material (Type 3 light body Exaflex ® ) was employed to make the negative cast, and polyurethane resin (FEROCA S.A.) to make the replica.…”

Dental Scratches and Handedness in East Asian Early Pleistocene Hominins

“…The scratch number in the Meipu I 1 is less than those in Vindja 290 (Frayer et al, ) and OH65 (Frayer et al, ). However, the number of scratches on the Meipu I 1 is greater than most other specimens of H. heidelbergensis and H. neanderthalensis (Lozano et al ., ; Hillson et al, ; Estalrrich & Rosas, ). The great number and overlapping pattern of the dental scratches in Meipu I 1 imply a habitual “stuff and cut” activity during the lifetime of this individual.…”

“…Faurie & Raymond, ). Additionally, the orientation of cutmarks on the labial enamel surface of human anterior teeth has been recognised as evidence of handedness (Bermúdez de Castro et al, ; Fox & Frayer, ; Lozano‐Ruiz et al, ; Hillson et al, ; Frayer et al, , ; Volpato et al, ; Estalrrich & Rosas, , ; Willman, ).…”

Ectopic maxillary third molar in Early PleistoceneHomo antecessorfrom Atapuerca‐Gran Dolina site (Burgos, Spain)

“…Therefore, the identification of pathological conditions in hominins remains an important finding in the assessment of the health status and behavioral patterns in an individual and/or population (e.g., Crovella & Ardito, ; Kappelman et al, ; Lovell, ; Martín‐Francés et al, ; Martín‐Francés, Martinón‐Torres, Gracia‐Téllez, & Bermúdez de Castro, ; Sun et al, ; Trinkaus & Villotte, ). In particular, the identification of dental pathologies in extinct species contributed to expanding our knowledge about these species, including: dietary preferences, use of medicinal plants to relief pain from infectious processes, metabolic stress or evidence of handedness (Cunha et al, ; Estalrrich & Rosas, ; Hardy et al, ). Although dental impaction, defined as the cessation of tooth eruption due to a physical barrier or due to tooth malposition (Bondemark & Tsiopa, ; Mortazavi & Baharvand, ), is quite common in modern humans (Hashemipour, Tahmasbi‐Arashlow, & Fahimi‐Hanzaei, ; Mortazavi & Baharvand, ) this condition is comparatively rare in fossil hominins.…”