Description du sujet de thèse

How did the genus Homo converge towards a single representative, when the fossil record of the human branch indicates a plurality of species for more than three million years? The differences in the adaptive trajectories of Homo and paranthropes, the other hominins that became extinct just over a million years ago, are undoubtedly the result of multiple and diverse interactions of a set of mechanisms that need to be considered in their full ecosystemic context. However, to date, no team or model, whether deterministic (based on differential equations) or probabilistic (frequentist, Bayesian, etc.), is capable of taking an integrated view of the impact on human evolution of mechanisms such as intra- and interspecific competition, differentiation of ecological niches and in particular diets, diversification of behaviour or the emergence of cognitive and cultural differences. Similarly, these models do not allow us to study the impact of volcanism or climatic fluctuations on the evolution of species, even though they have a direct influence on the distribution and availability of biotic and abiotic resources (type, quality, diversity, spatio-temporal accessibility), both regionally and globally.

So, while many factors may have influenced human evolution, we wonder whether trajectories other than the one observed (a priori contingent) would have been possible. Although this trajectory cannot be 'replayed', it is possible to test this hypothesis using a possibilistic modelling approach, which allows the known causal factors behind this evolution to be taken into account or not.

Possibilistic models of the EDEN type, which are used to study the histories of present-day socio-ecosystems, are well suited to this problem, as they are qualitative and accommodate knowledge and data of contrasting natures (e.g. physico-chemical, climato-hydrological, bio-ecological, etc.) and unevenly distributed in time and space, such as the partial data from palaeontological and archaeological records.

The aim of this thesis project is to attempt to answer the question of the contingent nature (or not) of human evolution, by assembling as much expert knowledge as possible on palaeoecosystems from several scientific disciplines. Our models will not be able to test the contingency of the Homo genus, but a contingency, one that would exhibit different trajectories based on a set of mechanisms and their interactions, possibly played out in a different order, or not played out at all.

More specifically, the aims of the thesis are 1) to compile this contrasting expert knowledge on palaeoecosystems, 2) to formalise this knowledge within a possibilistic model, using the EDEN (Ecological Discrete Event Network) formalism, and 3) to explore alternative (contingent) evolutionary scenarios of the Homo genus system and its associated ecosystems between 4 and 1 Ma. This will be done by analysing the various trajectories calculated by the model and dependent on climate, palaeoecology, niche partitions, material cultures, etc.
The formalisation of expert knowledge (objective 1) will be based on (i) exchanges with a multidisciplinary community already made up of archaeologists, palaeontologists, palaeoclimatologists, geologists, etc. whose fields of study are the fossiliferous sites of Pliocene and Lower Pleistocene East Africa. These exchanges will be supplemented by (ii) data from the literature and (iii) technical constraints linked to the design of possibilistic models. The development of the model (objective 2) and the exploration of evolutionary scenarios (objective 3) will be carried out on a Jupyter platform and with models that are already available.

Contexte de travail

This thesis work will be carried out as part of the 80PRIME ALEA project funded by the CNRS Mission for Transversal and Interdisciplinary Initiatives (MITI).

The PhD student will be based at the Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE) in Aix en Provence, France. He/she will be assigned to the CLIMAT team. See https://www.cerege.fr for details of the host laboratory.

To formalise the expert knowledge, it will be necessary to work with the researchers directly involved in the ALEA project (in Paris, Bordeaux, Poitiers, Montpellier) and with those of the interdisciplinary research group of the GDR RIFT.

The doctoral student will be co-supervised by a thesis director and a co-director who respect gender and cultural diversity. A thesis committee will meet at least once a year to monitor the progress of the thesis project and the student's professional project.

Contraintes et risques

PROFILE OF CANDIDATES
- Successful completion of a Masters degree in palaeontology, evolutionary biology, archaeology or palaeoecology before starting this post.
- Have a good basic knowledge of computer tools and languages such as R and Python.
- Work independently and be self-motivated.
- Be logical and rigorous.
- A strong interest in fundamental and applied research, particularly in the field of palaeontology.
- An appreciation of interdisciplinarity and a proactive willingness to collaborate in different fields.
- Fluency in English.
- Good communication skills (oral and written) and social skills.