Hominin BipedalismS: Exploration of bipedal gaits in Hominins thanks to Specimen-Specific Functional Morphology – HoBiS

HoBiS has designed an integrated approach based on 4 scientific work packages:
WP1 - Constitute a large comparative anatomical and biomechanical database for a large diversity of primates (humans, Chimpanzees, Baboons, Gibbons,...), as well as fossil hominins. These data are of 3 main types: fossil morphology and comparative anatomy of the locomotor system thanks to 3D imaging and dissection, as well as comparative movement thanks to experimentation on living species.
WP2 - Anatomical transfer reconstruction of locomotor anatomy and musculoskeletal models (MSM) from partial information. Fossils are generally incomplete with indirect soft tissue clues. HoBiS develops software under a contract to generate complete anatomical models and plausible MSM from partial anatomical data and a set of assumptions (mass distribution,...).
WP3- Biomechanical simulation and validation. The Decision Support System (DSS) is based on a simulator to predict a plausible bipedal locomotion based on a paleoanthropological heuristic and a given MSM. Due to the high complexity of the system, the exploration of the potential motion space is time consuming and leads to an unusable DSS, and may lead to a sub-optimal solution. We therefore propose to explore a coarse-to-fine simulation approach: the results of a kinematic controller based only on joint angles are used as an initial estimation to then integrate a dynamic controller based on joint torques.
WP4 - Application to fossil specimens. We apply the specific functional morphology to a sample of 7 species selected because they allow to answer specific questions on hominine bipedalism.

The work focused on the scientific Work Packages WP1 (Comparative and fossil data), WP2 (Reconstruction of anatomical structures) and WP3 (Walking simulation tools).
Works in WP1 generated individual anatomical (CTScan) and movement data for 4 olive baboon (Experiments on trained animals at the CNRS Primatology Station) . A complementary set of cross-sectional data (CTScan, dissections, and mid-life experiments) was also collected for this species over a large population. Work on the other species is in progress. The 3D database of fossil hominin footprints is constituted and 3D models of the bones of Neanderthals, modern humans and Australopithecus afarensis are available. A database integrating these different types of data (3D images, movement, ...) is under construction and will be eventually accessible to the community.
The work of WP2 focused on the development of a software in the framework of a contract with the company Anatoscope. The proposed solution is presented in 2 modules allowing 1) to generate statistical anatomical atlases augmented with deformation modes and 2) to reshape and deform a given atlas on a partial bone in order to propose a reconstruction of the missing parts and the areas of interest (points, surfaces) by anatomical transfer. In this WP, a finite element MMS specific to the functioning of the human foot has been adapted to the other studied species.
The work of WP3 has allowed designing of a new method for the simulation of bipedal locomotion based on a kinematic structure and footprints to be followed. This method guarantees a symmetrical and periodic movement. Work on physical simulation has started. One of the difficulties of this dynamic simulation is the management of contacts and external forces, especially underfoot in the case of walking.

The next few months will allow the finalization of the collection of comparative and fossil data and their integration into the dedicated database. The tool for the reconstruction of anatomical structures will be operational in the spring of 2021 and will allow the first anatomical reconstructions for specimens hitherto only partially known. The kinematic simulation tool developed will enable the first simulations of bipedal walking for the best represented fossil species to date (Neanderthal, Australopithecus afarensis )and their comparison with that of modern man. The physical simulation will take place later in 2021. In the end, HoBiS aims at reconstructing the locomotor anatomy and bipedal walking of 7 fossil species selected because they allow to answer specific questions about bipedalism and hominine evolution. This will further demonstrate the spectrum of action of this new methodology and thus considerably improve our knowledge of the diversity of bipedal gait in hominines.

The 2 first years of HoBiS lead to 6 scientific communications and the publication of 6 articles in peer reviewed journals:
DUVEAU J, BERILLON G, VERNA C, Laisné G, and CLIQUET D. 2019. The composition of a Neandertal social group revealed by the hominin footprints at Le Rozel (Normandy, France). PNAS 116(39):19409-19414
DUVEAU J, BERILLON G, VERNA C, LAISNÉ G, AND CLIQUET D. (sous presse) On the Tracks of Neandertals. The Ichnological Assemblage from Le Rozel (Normandy, France). In Pastoors A. & Lenssen-Erz T. (ed) Reading Prehistoric Human Tracks, Springer.
HARENG N, WATIER B, MULTON F (2020) Prediction of plausible locomotion using nonlinear kinematic optimization. Computer Methods in Biomechanics and Biomedical Engineering 23 (sup1), S136-S138
PERRIER A., BUCKI M., SUPIOT A., DELCROIX N., LAMBERTON F., DRUELLE F., HERREL A., BERILLON G., 2019, Comparative functional anatomy using rigid multibody simulation and anatomical transfer: Homo sapiens, Pan paniscus and Papio anubis. Computer Methods in Biomechanics and Biomedical Engineering, 2019, 22, S1, S457-S459
DRUELLE F., AERTS P., D’AOÛT K., LACOSTE R., MOLINA VILA P., RIMBAUD B., BERILLON G., 2019, Muscle recruitment pattern of primates (bipedal vs quadrupedal): is it different to other quadrupedal mammals? Computer Methods in Biomechanics and Biomedical Engineering, 2019, 22, S1, S82-S83
DUVEAU J., MULTON F., MARCHAL F., ANDUZE D., BERILLON G., 2019, Walking with hominins: from the reconstruction of a plausible anatomical model to gait energetics in Neandertals. Methodological aspects. Computer Methods in Biomechanics and Biomedical Engineering, 2019, 22, S1, S519-S520

HoBiS is a pluridisciplinary research project, fundamental in nature and centred on palaeoanthropological questions related to habitual bipedalism, one of the most striking features of the human lineage. Recent discoveries (up to 7 My) highlight an unexpected diversity of locomotor anatomies in Hominins that lead palaeoanthropologists to hypothesize that bipedalism in hominins took distinct shapes in the course of human evolution; these bipedal locomotions were not transitional nor inefficient, but on the contrary probably constituted efficient and well-coordinated positional modes. A much more complex scenario of hominin evolution than that proposed only few years ago thus emerges where knowledge on locomotor anatomy takes an increasing important role.
HoBiS wants to shed new light on our phylogenetic history by integrating to these scenarios new knowledge on the possible bipedal capacities in relation to locomotor anatomy. As a main methodological objective and improvement in the field of Evolutionary Anthropology and Functional Anatomy, HoBiS wants to develop a totally new specimen-specific approach in evolutionary anthropology named Specimen-Specific Functional Morphology: a standardized and specimen-specific decision-support-system (DSS) that aims to better assess the form-function relationships based on partial anatomical knowledge. To achieve these objectives, HoBiS will integrate and improve fundamental and technical knowledge from various scientific fields: Hominin’ locomotor anatomy, comparative functional anatomy and biomechanics, as well as anatomical modelling and motion simulation, to address the following challenges: inferring plausible complete locomotor anatomies based on partial fossil remains, to link these reconstructed anatomies and corresponding musculoskeletal models (MSM) to plausible gait using simulation. Both challenges need to collect a wide database of comparative anatomy and gait biomechanics to calibrate and validate the system.
In that aim, HoBiS gathers 5 French labs (3 partners) and 1 Belgian (non-funded) research centers and experts in evolutionary anthropology, in functional anatomy, biomechanics, numerical modelling and simulation. They designed a work program around 4 main scientific work packages: WP1 - Gather a large database of comparative anatomy (living humans and non-human primates (NHP) and fossil specimens) and motion (living humans and NHP) - We expect HoBiS to provide the widest comparative anatomical and bipedal gait database for a large variety of NHPs, as well as humans and fossil hominins. WP2 – Design a computer-assisted modeling of full anatomy and MSM based on partial anatomical information. We expect HoBiS to reconstruct numerous hominin species, and significantly improve our knowledge of Hominin locomotor anatomy. WP3 – Tools of simulation of bipedal gaits - We expect HoBiS to propose in-silico prediction of plausible locomotion with regards to specimen-specific MSM developed in WP2. WP4 - Application scenarios on fossil specimens - We expect our approach to significantly improve in accuracy and numbers of species (7 hominin species) our knowledge of the bipedal capacities in hominins all along our phylogenetic history.We expect the Specimen-Specific Functional Morphology to significantly increase fundamental knowledge on mechanisms of bipedal walking and the anatomical basis thereof in living primates and hominins. It will allow us to address the complexity of our evolutionary history, and could be reused in the field of Evolutionary Anthropology and comparative biology to address other functions. Important impacts are expected in the other fields including biomechanics, motor control, sciences of motion and robotics.