Task division in hunters-gatherers does not depend on the capacities of each gender

Task division in hunters-gatherers does not depend on the capacities of each gender

 

In current hunter-gatherer groups, women usually transport greater loads than men, therefore some scientists had indicated they were energetically more efficient when performing these tasks. The Paleophysiology and Ecology of hominins group of the Centro Nacional de Investigación sobre la Evolución humana (CENIEH), headed by doctors Ana Mateos and Jesus Rodriguez, has published a paper in the American Journal of Human Biology, showing that men and women use the same energy carrying a load of certain weight.

An experimental study was designed to conduct this research, in which the energy used during the load carriage by men and women was compared, measuring different body parameters. 48 volunteers of both genders participated in the tests developed in the BioEnergy Laboratory of CENIEH.

Actually, the energy cost depends solely on the body size of the individual, not on the gender. As Olalla Prado, lead author, explains, “besides the obvious differences in the body size between genders, there is no evidence of any physiological advantage favoring women in the transport of loads”.

Nevertheless, despite having lesser body size, normally women carry more weight than men among the hunter-gatherer groups. On this regards Ana Mateos indicates that in indigenous groups like the Ache, the Pume, the Efe, the Hiwi, or the !Kung, men and women invest different times in the activities of searching for and carrying resources. “In addition, the energy cost used in these tasks also depends on their abilities and their physiological and/or reproductive conditions”, she adds.

Therefore, that division of work must be explained by other factors. In those societies, women were dedicated to tasks that involved less risk, although not less importance, this way improving the viability of the group. Assuring the reproductive success is essential; lactation periods are long, and children must stay near their mothers during the first years of life. Exposing pregnant women or children to risky activities would have disastrous consequences for the group.

“Therefore, a division of tasks like that seen in those groups, is much more efficient, without that meaning differences in the capacity of one or the other gender to perform them”, concludes Jesus Rodriguez.

energy cost
Volunteer a the BioEnery Lab/CENIEH

Full bibliographic information

Prado-Nóvoa, O., Rodríguez, J., Vidal-Cordasco, M., Zorrilla-Revilla, G., Mateos, A. 2019. No sex differences in the economy of load-carriage. American Journal of Human Biology, e23352

brain fossils neuroanatomy

Brain, shape and fossils

Brain, shape and fossils

Emiliano Bruner has just published a paper on the shape of the brain over human evolution, which reviews the evolutionary relationship between humans and the other primates, as well as the most recent methods for comparing the principal variations between brain and cranium

brain fossils neuroanatomy
Credit: Emiliano Bruner

Emiliano Bruner, a paleoneurologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), has just published an overview article in the Journal of Comparative Neurology, on studies of changes in brain shape over the course of human evolution, which considers the evolutionary relationship between humans and the other primates.

Evolutionary neuroanatomy must integrate two different sources of information: fossils and living species. The fossils furnish data on the process of evolution, while living species do the same for the product of evolution. Unfortunately, the fossil record is incomplete and fragmented, and often cannot support validations for specific evolutionary hypotheses. Extant species can offer more comprehensive indications, but they do not represent ancestral groups or primitive forms.

Specifically, this paper reviews the limitations on studies of evolutionary neuroanatomy and the different contributions made by analyses of living primates and extinct hominins. For instance, the great apes are still interpreted as primitive biological models, even though these are species that have evolved independently of the path traced by the human genus. “Macaques or chimpanzees are frequently used as proxy for human ancestral conditions, despite the fact they are divergent and specialized lineages, with their own biological features”, says Bruner.

With regard to the fossils, these can furnish more direct information about the evolutionary process, but the limitations of the samples often do not allow scientific testing of our hypotheses, leading to a lot of guesswork. In fact, as Bruner explains, “independent lineages, such as the Neanderthals, ought not to be confused with ancestral modern human stages”.

Endocranial molds
The paper also introduces the most recent methods for computed morphometrics and biomedical image analysis, describing the principal variations in brains and endocranial molds (endocasts) for modern humans and extinct hominins, in addition to the spatial relationship between brain and cranium in the human genus.

Finally, it proposes integrating anatomical and cultural information with what is known in neurobiology when formulating hypotheses about cognitive evolution. One example would be the evolution of the parietal cortex and its schemes of cerebral connections.

This paper, entitled Human paleoneurology: shaping cortical evolution in fossil hominids, has been published in a volume dedicated to the evolution of the cerebral cortex, edited by Verónica Martínez-Cerdeño and Stephen Noctor, of the University of California at Davis (USA).

 

Full bibliographic information

 

"Human paleoneurology: shaping cortical evolution in fossil hominids", edited by Verónica Martínez-Cerdeño and Stephen Noctor Journal of Comparative Neurology (0). doi: 10.1002/cne.24591

Press release from the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) / ES


Tongzi hominids China Late Middle Pleistocene

Tongzi hominids are potentially a new human ancestor in Asia

Tongzi hominids are potentially a new human ancestor in Asia

Tongzi hominids China Late Middle Pleistocene
Tongzi teeth. Credit: Song Xing

The CENIEH has been participating in a comparative research about human teeth discovered in this Southern China site which has revealed that Tongzi's teeth do not fit the morphological pattern of traditional Homo erectus.

The Researchers María Martinón-Torres and José María Bermúdez de Castro have co-authored a research about the hominids from Tongzi which was published in the Journal of Human Evolution from the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) which reveals that Tongzi teeth do not fit the morphological pattern of traditional Homo erectus and that these teeth could potentially represent the highly targeted "Denisovans".

Between 1972 and 1983, the four teeth were discovered in the Yanhui Cave in Tongzi, Southern China. Their chronology is between 172,000 and 240,000 years old and they were originally identified as late Homo erectus or ancient Homo sapiens.

This research was led by Song Xing from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing (IVVP). The morphology of hominid teeth has been reassessed by geometric morphometrical analysis and Micro-Computed Tomography (micro-CT) as well as through morphological standard comparisons.

Tongzi teeth have been primarily compared with hominids during the same chronological period (Late Middle Pleistocene) and/or in the same geographical region (East Asia). However, the comparative sample includes a wide range of hominids.

More generally, the results indicate the existence of more than one human population in East Asia during this period: one which may be taxonomically classified as Homo erectus (exemplified by fossils such as Zhoukoudian, Hexian and Yiyuan); and a second which may be characterized by the existence of derived traits more commonly observed in recent species of the Homo genus, such as crown symmetry, tongue thrusting and the simplified dentine surface of the third premolar.

"More genetic and fossil discoveries would be necessary to evaluate the taxonomy of the "non-erectus" populations of the Middle Pleistocene, such as the Tongzi hominids, which could be good candidates for the Denisovan ancestry," says María Martinón-Torres.

The Denisovans

These populations are related to the Neanderthals who lived in Asia during the Late Middle Pleistocene and the Upper Pleistocene period which was discovered in 2010 from the genetic analysis of a phalanx and a tooth found in the Denisova cave in the Altai massif (Russia). An abundant amount of genetic information has been collected from the Denisovans but there are very few fossil remains. Therefore, both their physical appearance and their identification in the fossil record remain a mystery.

 

Full bibliographic information

Xing, S., Martinón-Torres, M., & Bermúdez de Castro, J. M. (2019). Late Middle Pleistocene hominin teeth from Tongzi, southern China. Journal of Human Evolution, 130, 96-108. doi: 10.1016/j.jhevol.2019.03.001.

 

Press release from Centro Nacional de Investigación sobre la Evolución Humana CENIEH/ (ES)


The oldest assemblage of antler mining tools in the Iberian Peninsula undergoes restoration

The oldest assemblage of antler mining tools in the Iberian Peninsula undergoes restoration

antler mining tools Iberian Peninsula Pozarrate
Conservation and Restoration Laboratory

The team at the Conservation and Restoration Laboratory at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) has just concluded its intervention on the oldest assemblage of antler mining tools in the Iberian Peninsula, dated to around 6,000 years old, and recovered during the 2018 excavation campaign directed by the CENIEH geologist Andoni Tarriño Vinagre.

This consists of seven remains of red deer antlers encountered in the quarry of Pozarrate (Treviño, Burgos), one of Spain's most important Neolithic flint mining operations. These tools are at least 1000 years older than other similar antler tools associated to prehistoric copper mining.

The intervention, comprising curative conservation and restoration work, was made complex by the conditions of preservation of the antlers, due in turn to their morphology and composition, aggravated by damp and the type of sediment present in the quarry. “A process of controlled desiccation was necessary so that the morphology and inherent information in the pieces was not lost”, explains Pilar Fernández Colón, head of the Conservation and Restoration Laboratory at the CENIEH.

Once restored, these tools will be studied by specialists in bone industry, and will be analyzed using non-destructive techniques, such as as micro-computed tomography. And Antonio Tarriño will present these findings to the scientific community at the international conference on mining archeology organized by the UISPP Commission on Flint Mining in Pre-and Protohistoric Times, in Warsaw, where the greatest specialists in the field will meet in September.

2019 Excavation campaign
In this year's excavation campaign, which is to take place during the month of July, work is going to continue on exposing the rocky substrate with flint which was the object of the mining activity, and it is hoped to reach a depth of at least 5 meters in the bottom of the quarry.

“We also expect to continue recovering more antler tools among the utensils employed in the operation, such as: ophite sledgehammers, flint picks and hammers and tens of thousands of fragments of waste flint from the operation”, says Tarriño.

This project by the CENIEH is receiving financial and infrastructure support from the Ayuntamiento de Treviño, the Universidad del País Vasco (UPV/EHU), the Junta de Castilla y León and the Diputación Foral de Álava. “Moreover, given the complexity and interest of the data we are getting, we have managed to extend the duration of the MINECO Project which this research is part of (HAR2015-67429-P), for one year”, he adds.

 

Press release from Centro Nacional de Investigación sobre la Evolución Humana CENIEH/ (ES)