HOMinin TECHnology Cognition, motricity and behaviour of the first stone-tool makers – HOMTECH

Interdisciplinary in nature, the ANR HOMTECH is based both on field data collected by the West Turkana Archaeological Project (WTAP/MKP dir. S. Harmand, which has the particularity of having a quasi-continuous sedimentary sequence between 4 and 0.7 Ma, including the oldest lithic assemblages, dated at 3.3 Ma (Lomekwi 3)), and on recent discoveries of archaeological remains, fauna and hominins in eastern, central and southern Africa. In order to meet our objectives, we have developed (1) technological analyses of lithic production; (2) geochemical analyses of soils and faunal remains; (3) comparative approaches to fossil hominins and current human and non-human primates (internal and external morphology (CT-Scan data), microwear, morphometry, neuroanatomy); (4) experimental archaeological replication programs combining biomechanical analysis of the upper limbs (measurement of muscle activity (EMG) and mobility of the upper limbs (kinematics)) and non-invasive analysis of brain activity (EEG), in order to identify the anatomical requirements and the cognitive and motor capacities involved in the production of the oldest lithic assemblages.
The re-evaluation of the neuro-cognitive processes involved in planning was coupled with a second approach, this time morpho-functional, which integrated human biomechanics and comparative morphology of upper limb elements. Initially, the biomechanical axis assessed the level of interaction between morphology and percussion technique inferred from late Pliocene and early Pleistocene archaeological records using an expert archaeological experimenter. Kinematic and electromyographic analyses were used to record the degree of muscular and articular load on the expert's upper limb during percussion techniques. The biomechanical data collected then fed into a musculoskeletal model of the 'hominin' upper limb, implementing morphological features classically identified in fossil hominins.

The integration of observations and the mobilisation of our different fields of expertise (from archaeology, neuroanatomy, biomechanics, palaeontology and geology, etc. ) has led to valuable comparisons which, when reconsidered within a coherent theoretical framework, have resulted in a re-evaluation of the taxonomy and diversity of late Pliocene and early Pleistocene hominins (Prat, 2022), their phylogenetic relationships (Capparos and Prat, 2021, 2022), their environmental setting (Boës et al. , 2024; Quinn et al., 2021), their range of subsistence behaviours (Daujeard and Prat, 2022; de Chevalier et al., 2022; Garcia et al., 2021; Hanon et al., 2021) and their manipulative capacities (Macchi et al, 2021; Prat, 2023) as well as the brain regions involved in cognitive operations related to planning, such as foraging, in extant non-human primates (Louail et al., 2019; Bouret et al., 2020, 2024). Furthermore, the production of lithic artefacts is not that different from a biomechanical point of view, suggesting the absence of a facilitating morphology (Macchi et al., 2021).
In parallel with this work, descriptions of the oldest hominin remains known to date have been published, and have also fed into our reflections on the form-function relationships of the upper limb (Daver et al., 2022; Blasi-Toccacceli, 2022).
HOMTECH has thus provided a better understanding of the diversity of hominins from the late Pliocene and early Pleistocene in Africa, their environmental and cultural context and the form-function relationships of the cranial, dental and postcranial skeletons of these ancient hominins. This clarification of the conceptual framework for interpreting the morphology of ancient hominins was supported by experimental (biomechanical, neuroanatomical) and morphological (e.g. cladistics, quantification of 2D and 3D shape) approaches.

These results contribute to the ongoing debate on the definition of the genus Homo, its behavioural specificities and the underlying evolutionary processes. All these aspects are essential for understanding the origin of technological skills (innovation) and the processes of hominization. This is a vast debate linked to a major question: what makes us human? And how can we define our own genus, the Homo genus?
HOMTECH has enabled us to better define the form-function relationships of the cranial, dental and postcranial skeletons of ancient hominins. It appears that on the one hand certain hominins (e.g. Paranthropus), hitherto excluded from the role of stone and bone-tool makers, must now be considered seriously, and that on the other hand the production of late Pliocene and early Pleistocene lithic artefacts is not so different from a biomechanical point of view, suggesting the absence of a facilitating morphology. This clarification of the conceptual framework for interpreting the morphology of ancient hominins has been fuelled by experimental (biomechanical, neuroanatomical) and morphological (e.g. cladistics, quantification of 2D and 3D shape) approaches. At this stage, a return to the study of morphological variation in the first taxa of the genus Homo and Paranthropus in particular is now necessary and constitutes a most promising line of research.
In terms of analysing the percussive gesture during the production of stone tools, studying the variation in the gestures involved during percussion, according to different levels of skill, may prove useful in order to better identify the anatomical (and not osteological) requirements necessary for this activity.
These prospects for morphological, biomechanical and behavioural research will also benefit from the new partnership agreement between the University of Poitiers, in particular the PALEVOPRIM laboratory, and the Vallée des Singes zoological park. The agreement has three parts:
A «Research« section, the aim of which is to carry out observations on extant primates in the Vallée des Singes in order to compare and improve interpretations of the primate fossils held by the University laboratory.
A «Heritage conservation« component, to safeguard the bones of the end-of-life primates from the Vallée des Singes, and give them a scientific life by integrating them into the collections of the University of Poitiers.
A «Knowledge transfer« component aimed at students at the University of Poitiers, in particular those studying for a Masters in Palaeontology, as well as the general public, with joint Palevoprim - Vallée des Singes mediation activities on the evolution of primates (lectures, explanatory panels, workshops, etc.).

This project has already resulted in the publication of 18 articles in international journals such as L'Anthropologie, Cortex, Elife, Frontiers in Evolution and Ecology, iScience, Journal of Archaeological Science: Reports, Journal of Human Evolution, Nature, Palaeogeography, Palaeoclimatology, Palaeoecology, Philosophical Transactions of the Royal Society B: Biological Sciences and 5 book chapters.
The results have been presented at 36 conferences. All our published articles have been posted on Hal and a website dedicated to this project (http://homtech.prd.fr/) has been set up.
We have also been active in disseminating information to the general public, through the publication of articles in Archeologia and at conferences for the general public.

Scientific production:

Blasi-Toccacceli A., Daver G., Domalain M. (2022). BMSAP 34 (2), 1-13.
Boës, X, Van Bocxlaer B., Prat S., Feibel C., Lewis J., Arrighi V., Taylor N., Harmand S. (2024). Journal of Human Evolution, 186, 103466.
Bouret S. Paradis E., Prat S., Castro L., Gilissen E., Garcia C. (2024). Elife.87780.2
Bouret S., Louail M., Prat S., Garcia C. (2020). Med Sci 36 : 103-105.
Caparros M., Prat S. (2021). iScience 24, 102359.
Caparros M., Prat S. (2022). Star Protocol 3, 101191.
Daujeard C., Prat S. (2022). Frontiers in Evolution and Ecology 10, 103389.
Daver G., Guy F., Mackaye H.T., Andossa L., Boisserie J.-R., Moussa A., Pallas L., Vignaud P., Nekoulnang C. (2022). Nature 609, 94-100.
de Chevalier G., Bouret S., Bardo A., Simmen B., Garcia C., Prat. S. (2022). Frontiers in Evolution and Ecology. 10: 812804.
Garcia C., Bouret S., Druelle F., Prat S. (2021). Philosophical Transactions of the Royal Society B: Biological Sciences. 376: 20190667.
Hanon R., Francesco d’Errico F. Lucinda Backwell L., Prat S., Péan S., Patou-Mathis M. (2021). Journal of Archaeological Science: Reports 39 , 103129.
Harmand S. 2021. In : Un bouquet d'ancêtres - Premiers humains : qui était qui, qui a fait quoi, où et quand ? Dir Yves Coppens & Amélie Vialet. CNRS Éditions.
Louail M., Gilissen E., Prat S.*, Garcia C.*, Bouret S.* (2019). Cortex, 118: 262-274
Macchi R., Daver G., Brenet M., Prat S., Hugheville L., Harmand S., Lewis J., Domalain M. (2021). J. R. Soc. Interface, 18, 20201044.
Prat, S. (2022). L'Anthropologie, 126, Issue 4,103068.
Prat S. (2023). L’Anthropologie, 127, issue 4, 103187.
Quinn, R. L., Lewis, J., Brugal, J. P., Lepre, C. J., Trifonov, A., Harmand, S. (2021). Palaeogeography, Palaeoclimatology, Palaeoecology, 562, 110074.

The transdisciplinary project HOMTECH (HOMinin TECHnology. Cognition, motricity and behaviour of the first stone-tool makers) seeks to reconstruct the cognitive capacities, motor capabilities and subsistence behaviours of the first stone tool makers (Lomekwian and Oldowan), integrating archaeology, palaeoanthropology, archeozoology, neurobiology and biomechanics.
Since the discovery of the oldest archaeological site yet found at 3.3 million year old stone tools in Kenya (Lomekwi 3: LOM3), by members of this project, which (1) pushed back the beginning of the tool archaeological record by 700,000 years, and (2) pre-dated the Homo genus by 500, 000 years, some fundamental questions concerning the origin of technological skills and hominization processes must now be revisited. This innovative transdisciplinary research project will provide a unique opportunity to discuss the uniqueness of the oldest stone-tools, fill the gap between Lomekwian and Oldowan sites, understand the differences in terms of complexity in the sequencing actions of Lomekwian and Oldowan, and appreciate if they were used to access animal carcass resources. This project attempts to better apprehend the identity of the first stone-tool makers, the Pliocene and early Pleistocene hominin diversity and its link with behavioural processes (subsistence, landscape use). It will also contribute to better understand the evolution of higher order cognitive functions such as planning, involved in tool-making and foraging, by bridging the gap among existing data on modern human, non-human primates and hominin fossils. It will also allow to distinguish the sets of upper limb and hand characters functionally associated with human-like manipulation from those linked to retained arboreal locomotor behaviour.
This project will be focused on fieldwork and fossil studies from Lake Turkana, Northern Kenya, which is crucial in human evolution studies and considered as “Cradles of Humankind”. We will focus on the period between 3.5 and 1.5 Ma, which corresponds to the first lithic industries and the period of a main shift in terms of culture, behavior, anatomy and climate. This multidisciplinary project will use the extremely rich field data collected by the West Turkana Archaeological Project in Northern Kenya (WTAP/MPK, dir. S. Harmand), including the discovery of a stone tool assemblage securely dated at 3.3 Ma (LOM3), as well as the recent discovery of new archaeological sites and faunal and hominin remains. We will undertake technological analyses of the lithic production, using the chaîne opératoire concept as a tool for analysis, as well as a comparative anatomy and morphometrics on hominins, humans and non-humans primates (osteology, neuroanatomy). We will also develop an experimental replication program, combining neurophysiology and biomechanics to assess the biomechanical and cognitive mechanisms involved in producing the oldest technologies (Lomekwian and Oldowan).

These results will also contribute to the on-going debate on the definition of the genus Homo, its behavioural specificities and underlying evolutionary processes. It is part of a huge debate related to one major question: does technology, i.e. knapping stone tools, is linked to the Homo genus and make us human?
This fundamental research project on prehistoric archaeology, cognitive archaeology, human evolution and cultural heritage intends to contribute to the advances of knowledge in the domain of the dawn of innovation, cognition, motricity and human origins. This research field has a strong appeal to a large scientific and non-scientific audience, either nationally or internationally. The project, based on fieldwork data and analytic data, should provide the first long-term evolutionary framework for understanding the biological, and behavioural contexts of the first hominin technologies, which are crucial to understand the origin of technological (innovation) skills and hominization processes.