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Right-handedness goes back to first Homo species, Homo habilis


Homo sapiens are considered to be the only species with a predominance of a preferred use of the right hand, with a ratio of 9 right-handed to 1 left-handed people. However, when did the human handedness appeared in human evolution remains unknown. An international research recently published and led by Marina Lozano, researcher at IPHES (Institut Català de Paleoecologia Humana i Evolució Social), shows that this behaviour is more ancient than it was thought. At population level, Neanderthal as far as 130,000 years ago, showed a well-stablished hand preference as our species. Nevertheless, this practice goes back to Homo habilis showing that handedness is an ancestral characteristic of our genus.

Right-handedness goes back to first Homo species, Homo habilis
A. An incisor of Homo antecessor (Gran Dolina, Atapuerca, Spain) and B. an incisor of pre-Neanderthal
(Sima de los Huesos, Atapuerca, Spain) [Credit: Marina Lozano/IPHES]
The scientific community has developed a huge amount of studies focused on handedness and brain laterality in hominins. However, in this work, a large sample has been analyzed, for the first time, following the same methodology. That is 120 individuals of five different human species (Homo habilis, Homo antecessor, preneanderthals, European Neanderthals and Homo sapiens), spanning almost 2 million years.

The main research teams focused on the study of handedness in fossil hominins are involved in this work. So, this is the result of an international collaboration between researchers of Spain, USA and Italy. Thanks to this work “we can affirm that the trend to have a preferred hand is an intrinsic characteristic of our genus. The handedness was established slowly in each of the species who precede us. From this research, we can do some inferences because handedness implies brain laterality that is closely related to language”, mentions the researcher Marina Lozano.

This international team studied the cultural dental wear, specifically the striations (cut marks) that result from the use of the mouth as a third hand, when some material is held between the anterior teeth and cut with a lithic tool. These marks are analyzed with environmental scanning electron microscopy.

The study is published in Evolutionary Anthropology.

Source: IPHES [January 28, 2018]

TANN

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