Eleven of the thirteen Neanderthals that inhabited the El Sidrón cave (Asturias) were right-handed. This is one of the results of a study by the Higher Council for Scientific Research (CSIC) in which the stretch marks of more than 60 teeth of this hominid species have been analyzed. The work, published in PLOS ONE , shows, along with other anatomical and functional evidence of brain lateralization, that Neanderthals had a pattern of brain asymmetry similar to that of modern humans .
” Manual laterality is a reflection of a specialized organization of the brain , which is why its evolutionary origin has been the subject of research for decades,” explains CSIC researcher Antonio Rosas, from the National Museum of Natural Sciences. Although some primates may have a certain tendency to preferentially use one of their hands, a strict lateralization is only observed in human species.
According to Rosas, director of the research, being able to jointly study 11 individuals from the same Neanderthal group constitutes a unique fact and confirms that laterality in the use of the right hand is a population phenomenon . It remains to be determined whether the two remaining individuals of the group of 13 Neanderthals from El Sidrón were right-handed or left-handed, since the dental pieces are not preserved among their remains.
Using electron microscopy, the researchers have been able to study in detail the orientation and directionality patterns in incisors and canines of the so-called cultural striae . To aid in the elaboration of works, the prehistoric settlers used the mouth as a third hand , in what we call the “grab and cut gesture”. “With their mouths they held skins, meat, tendons and plant fibers, materials that they tightened with one hand and cut or scraped with the other; during these practices, stone instruments sometimes brushed the teeth, and left characteristic marks,” he says. Almudena Estalrrich, co-author of the work.
This study shows that the preferential use of one hand over the other in Neanderthals was established since childhood , as occurs in modern humans, since among the 11 individuals analyzed there is a child between 6 and 8 years old. that presents the same laterality pattern as adults.
Of the 27 Neanderthals analyzed around the world to date, only two have shown evidence of a preferential use of the left hand, a percentage that coincides with the cerebral laterality observed in modern humans.
