PAVARD Samuel

Main research interest :

I am a demographer with broad interests in understanding the biological, environmental, cultural and social determinants of demographic traits (as fertility and survival) in humans.

Questions that particularly interest me include (i) how and why such traits vary over time and between populations, (ii) how these demographic traits influence (and are influenced by) population dynamics, and (iii) how they have evolved during human history. My main research focuses are currently on two aspects:

• The investigation of the joint evolution of life-history and sociality (in the ecological sense) in our species.

• To study of the evolution of senescence in our species : Why do we age ? At what pace ? Do all functional systems age at the same pace ? What are the social drivers of - and the constraints on - senescence ?

A Mising girl in a rice field (Assam, 2003)

Crédits: 

© S.Pavard

Post-doctoral fellows

Victor Ronget (Funded by the ANR MathKinD) - Development and analysis kin & age structured model in humans

Tazzio Tissot (Funded by the labex BCDiv) - Vieillir pour ne pas mourir : coévolution de la sénescence et des cancers

PhD Students

Lucie Vanhoutte (with Emmanuel Cohen, Géraldine Duthé) - Évolution de la mortalité adulte sous les effets conjoints des transitions nutritionnelle, épidémiologique et démographique : le cas du Sénégal

Margaux Bieuville (with Tazzio Tissot) - Spatially-structured cellular demography: application to mutation accumulation in tissues and consequences for cancers and organism senescence.

Christophe Coste (with Frédéric Austerlitz) - The costs of reproduction in evolutionary demography : An application of Multitrait Population Projection Matrix models

Goki Ly (with Raphaëlle Chaix and Frédéric Austerlitz) - Du système de parenté à la diversité génétique dans les populations humaines d’Asie du Sud-Est

Julie Landes (with Pierre-Yves Henry) - Compromis entre traits d’histoire de vie et saisonnalité chez un primate hétérotherme

• Current Projects

ANR Project MathKinD - Mathematics of Kinship Demography: new developments and application to Humans

2019 - 2022

In coll. with. S. Cubaynes, C. Coste, G. Pison and J-M Robine

In social species, demographic processes (ie, growth, reproduction, migration, survival) are functions of cooperative/competitive interactions among individuals. In cooperative breeders for example, juveniles’ growth and survival depend on stage/age/size-structure transfers of resources from parents and from “helpers at the nest” siblings. In such species therefore, kinship interplays coevolve with life-history traits (LHT). Humans in particular have evolved a peculiar life-history in which age- and kin-structured social interactions play a major role: a protracted juvenile period, a short but intense and hazardous reproductive period for females, ending with a menopause, and an extended post-reproductive life. However, the main evolutionary drivers of this coevolution between age-structured demography and kin-structured interactions are mostly unknown.

This is because the field of evolutionary ecology is still lacking a general theory for the study of the dynamic interplay between kinship interactions, population dynamics and evolution of LHT. Whilst, the tenets of the Hamiltonian theory for the evolution of sociality (Hamilton, 1964) - an individual’s inclusive fitness is determined by the costs (weighted by kinship coefficients) and benefits of kin investments - are well known at the individual level, its implications at the population level are still largely understudied. This is in particular the case for the inherent feedback circuit between demography and sociality: the system of age/stage/size-structured demography and kin-structured behaviors determines the dynamics of the population, which, in turn, regulates the distribution of kinship coefficients and therefore the opportunities and magnitudes of cooperative behaviors.

Who keeps children alive? is the title of a review from Rebecca Sear and Ruth Mace (2008, Evolution and Human Behavior). It is also a key question concerning the evolution of cooperative breeding and life-history traits in humans.

Crédits: 

© S. Pavard

The aim of the MathKinD project is twofold. Its first axis of research aim at providing a general mathematical method to infer kin distributions by stage/age/size, from any demographic model, by applying genealogical Markov chains methodology to Multitrait Population Projection Matrix (MPPM, Coste et al. 2017). The second axis of MathKinD is to implement close-kin demographic interactions (as for instance bi-parental care, grandparental care or siblings’ cooperation/competition) into MPPMs. With these models in hand, we will be able to disentangle the socio-demographic forces at stake in the coevolution of sociality with the peculiar LHT of our species, under different biological, environmental and cultural scenarios. We will also examine the reciprocal changes in kinship and demography of past transitioning societies (e.g., Neolithic), as well as enhance the demographic forecasting of contemporary populations that, whilst differing in their kinship systems, are all affected (and sometimes threatened) by ever increasing environmental perturbations.

Education :

• 2008 – Lecturer of the National Museum of Natural History, Paris, France

• 2005-2008 Postdoctoral fellow, Evolutionary Demography Team, Max Planck Institute for Demographic Research, Rostock, Germany

• 2000-2004 Ph.D thesis in Human Ecology and Demography, Musée de l’Homme, Paris, France. Subject : « Investissement maternel et survie de l’enfant:approche démographique, génétique et évolutive » (supervisor : Pr. E. Heyer).

• Rewarded by the “Prix Bertillon de la Société d’Anthropologie de Paris”, 2004).

• 1999 – 2000 Master’s Degree in Human Population Demography and Biology. Museum National d’Histoire Naturelle, Paris, France. Subject : « Study of selective pressures on BRCA1 breast cancer susceptibility gene » (supervisor : Pr. E. Heyer).

• 1998 – 1999 Bachelor’s Honours in Cellular Biology and Biochemistry, University of Sciences, Angers, France. Internship in epidemiology- Genetics, Center of Cancerology, Paul Papin, Angers, France. Subject : « Determination of an optimal strategy to detect BRCA1 mutations by analyzing familial breast and ovarian cancer profiles » (supervisor : Dr A. Daver).