Human evolution. Human-like hand use in Australopithecus africanus.

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Abstract

The distinctly human ability for forceful precision and power "squeeze" gripping is linked to two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of tools. However, it is unclear when these locomotory and manipulative transitions occurred. Here we show that Australopithecus africanus (~3 to 2 million years ago) and several Pleistocene hominins, traditionally considered not to have engaged in habitual tool manufacture, have a human-like trabecular bone pattern in the metacarpals consistent with forceful opposition of the thumb and fingers typically adopted during tool use. These results support archaeological evidence for stone tool use in australopiths and provide morphological evidence that Pliocene hominins achieved human-like hand postures much earlier and more frequently than previously considered.

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Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia.

Hamdallah Béarat, Denis Geraads, Zeresenay Alemseged … (2010)

The oldest direct evidence of stone tool manufacture comes from Gona (Ethiopia) and dates to between 2.6 and 2.5 million years (Myr) ago. At the nearby Bouri site several cut-marked bones also show stone tool use approximately 2.5 Myr ago. Here we report stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia, a research area close to Gona and Bouri. On the basis of low-power microscopic and environmental scanning electron microscope observations, these bones show unambiguous stone-tool cut marks for flesh removal and percussion marks for marrow access. The bones derive from the Sidi Hakoma Member of the Hadar Formation. Established (40)Ar-(39)Ar dates on the tuffs that bracket this member constrain the finds to between 3.42 and 3.24 Myr ago, and stratigraphic scaling between these units and other geological evidence indicate that they are older than 3.39 Myr ago. Our discovery extends by approximately 800,000 years the antiquity of stone tools and of stone-tool-assisted consumption of ungulates by hominins; furthermore, this behaviour can now be attributed to Australopithecus afarensis.

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Who's afraid of the big bad Wolff?: "Wolff's law" and bone functional adaptation.

Christopher B Ruff, Brigitte Holt, Erik Trinkaus (2006)

"Wolff's law" is a concept that has sometimes been misrepresented, and frequently misunderstood, in the anthropological literature. Although it was originally formulated in a strict mathematical sense that has since been discredited, the more general concept of "bone functional adaptation" to mechanical loading (a designation that should probably replace "Wolff's law") is supported by much experimental and observational data. Objections raised to earlier studies of bone functional adaptation have largely been addressed by more recent and better-controlled studies. While the bone morphological response to mechanical strains is reduced in adults relative to juveniles, claims that adult morphology reflects only juvenile loadings are greatly exaggerated. Similarly, while there are important genetic influences on bone development and on the nature of bone's response to mechanical loading, variations in loadings themselves are equally if not more important in determining variations in morphology, especially in comparisons between closely related individuals or species. The correspondence between bone strain patterns and bone structure is variable, depending on skeletal location and the general mechanical environment (e.g., distal vs. proximal limb elements, cursorial vs. noncursorial animals), so that mechanical/behavioral inferences based on structure alone should be limited to corresponding skeletal regions and animals with similar basic mechanical designs. Within such comparisons, traditional geometric parameters (such as second moments of area and section moduli) still give the best available estimates of in vivo mechanical competence. Thus, when employed with appropriate caution, these features may be used to reconstruct mechanical loadings and behavioral differences within and between past populations. Copyright 2006 Wiley-Liss, Inc.

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Environment and Behavior of 2.5-Million-Year-Old Bouri Hominids

J. d. Heinzelin (1999)

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Journal

Journal ID (iso-abbrev): Science

Title: Science (New York, N.Y.)

ISSN (Electronic): 1095-9203

ISSN (Print): 0036-8075

Publication date (Electronic): Jan 23 2015

Volume: 347

Issue: 6220

Affiliations

[1 ] School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, UK. Department of Anthropology, University College London, London WC1H 0BW, UK. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig Germany. Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa. m.skinner@kent.ac.uk t.l.kivell@kent.ac.uk.

[2 ] Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig Germany.

[3 ] Department of Anthropology, University College London, London WC1H 0BW, UK.

[4 ] Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Gusshausstrasse 27-29, 1040 Wien, Vienna, Austria.

[5 ] School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, UK. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig Germany. Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa. m.skinner@kent.ac.uk t.l.kivell@kent.ac.uk.

Article

Publisher Item ID: 347/6220/395

DOI: 10.1126/science.1261735

PubMed ID: 25613885

SO-VID: 04cf1d73-bcc1-41aa-9d1f-23d973d6b954

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