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Deconstructing the past: Modelling the locomotion of Miocene hominoids through computational techniques

Periodic Reporting for period 1 - DeMol (Deconstructing the past: Modelling the locomotion of Miocene hominoids through computational techniques)

Reporting period: 2020-03-01 to 2022-02-28

The DeMoL proposal focused on studying the relationship between skeletal design (form) and animal behaviour (through functional morphology and biomechanics) and how this relationship is influenced by the bone mechanical environment, as well as the phylogenetic and developmental control of bone morphology. In turn, this will allow making inferences on the locomotor affinities of Miocene hominoids, which is a key group of extinct primates to better understand the origin and evolution of the positional behaviours of living apes, including human bipedalism, because they already display some (but not all) of the postcranial morphological traits of extant hominoids and they have shown similar biomechanical requirements to human bipedalism.
Results derived from this research will contribute to increase the knowledge about primate evolution and palaeobiology, in particular, about how the evolution of our own way of moving and displace originated and evolved. Therefore, the project has inherent interest for society since it takes an important part of our own history as a species. The project outcomes will be also of interest for those students involved in the Earth Sciences disciplines, as well as to conservationists, public policy makers, and industries related to the field of Biodiversity in general for the following reasons. Palaeontology has become essential along time to understand future issues through a better comprehension of the past. During the last decades, this discipline has had a very strong commitment with Earth's ecosystems and biodiversity conservation policies, since results from different branches of the field of Palaeontology have provided important data to understand current and future species biogeographic distributions and responses under the effects of the global warming (which, in turn, have important social and economic implications). Such results allow designing effective strategies for the conservation of endangered species in the territory that are priceless nowadays. Therefore, Palaeontology brings us the opportunity to better understand the process and causes of extinction among different groups of animals through geological time by identifying how these taxa have historically responded to climatic instability and changes in their local conditions, as well as better understanding their bone response through biomechanics, development and ageing. Having a broad knowledge about the evolutionary path of apes will allow us to predict how they will develop in the future and establish conservation plans and policies, as well as conscious and responsible measures to preserve primate biodiversity.
The DeMoL proposal had two main objectives: 1) deciphering how loading regimes influence bone design on living primates’ hind limb through the identification of the predominant bone loadings and investigating the influence of phylogenetic relatedness on specific traits; and 2) shed light on the origin, tempo and mode of the positional behaviour evolution of the hominoid primates by applying the functional runes generated in extant primates to the extinct taxa.
The DeMoL project has been severely affected by the coronavirus pandemic, since it has run parallel to the sanitary global crisis during its implementation period (March 2020-February 2022). Therefore, it was necessary to reorganised and plan new ways to address the questions pointed out in the proposal with data that was collected before the beginning of the project or through collaborative works (e.g. research visits, training, and other activities planned for data collection had to be canceled).
In terms of scientific research, the focus has been put on two different works: the study of the hominoid proximal ulnar morphology and the analysis of the mechanical properties of the femoral diaphysis of the dryopiths (a group of Miocene stem hominids). Preliminary results for both works have been presented in international conferences (Pina and Nakatsukasa, 2020 and Pina et al., 2022) and manuscripts are being prepared for publication. The manuscript on the proximal ulna focuses on the study of the proximal ulnar morphology through multivariate statistical analysis and the estimation of the phylogenetic signal of the different variables. In the manuscript on the femoral cross-sectional properties, these are analysed on a variety of primate groups with the aid of machine learning techniques (also exploring the phylogenetic signal) to classify extinct taxa into locomotor groups. Preliminary results on the Iberian and Hungarian dryopths are promising. Finally, an additional study about the loading regimes at the lower limb, particularly at the fibula, will be performed by means of finite element analysis (FEA). This work is currently in an initial stage.
Apart from these manuscripts led by the applicant, she has also worked on other collaborative projects related to the main topics of this proposal: 1) investigation of the loading conditions at the primate hip by exploring how stress is distributed at the proximal femur; this work joins FEA and machine learning techniques. 2) Study of the calcar femorale of hominids with the aid of imaging techniques; it was found that this structure at the proximal femur is not limited to the bipedal humans and closer relatives, but it is also present in apes.
Results have been announced and disseminated through the social media account of the applicant, the ICAL group and the university department. Moreover, the applicant is building a website ( where she will publish and disseminate the outcomes related to the project. The website and the social media allow her to track the impact of the dissemination and communication of the results and activities related to the project.
For the training, the applicant has undertaken online courses in the different areas covered by the project, including training on methodological techniques and transferable skills.
The DeMol project is generating very interesting results that will allow us to better understand the relationship between bone’s form and function, mainly from a biomechanical point of view. The project is also contributing with new morphofunctional and biomechanical data on the limbs ofthe stem hominids that belong to the subfamily Dryopithecinae (a group of primates that lived 12-9 million years ago) and the African taxon Nacholapithecus, mainly regarding their ulnar and femoral epiphysis and shaft (although a study on the fibula is also ongoing). Thus, this project will expand our knowledge and understanding of the functional traits of these long bones and will allow us to do inferences on the positional behaviours of the extinct taxa and hypothesize about different evolutionary scenarios (through a multifaceted perspective) that lead to the origin and evolution of the bipedal behaviours characteristic of humans, further contributing to the better knowledge of our own species.
Primate hind limb loading regimes