Individual Differences, Collective Destiny

Dr. Fanie Pelletier, a new researcher at the Research Centre on Aging (CdRV), is contributing her knowledge of evolutionary biology to improve our understanding of aging.

Dr. Pelletier is an expert in evolutionary biology. As the Canada Research Chair in Evolutionary Demography and Conservation, she investigates the relationships between variations within an environment and their effects on behaviour, life history, and the longevity of long-living species (i.e., with long lifespans). For example, she investigates bighorn sheep populations in the Canadian Rocky Mountains.

Dr. Pelletier has a Ph.D. in behavioural ecology and is a professor at the biology department of the Université de Sherbrooke's faculty of science. She has developed applied know-how in the analysis of long-term data for populations which are both vast and targeted. This is just one of many levels of expertise she is bringing to the CdRV's Geroscience Axis.

She has recently co-authored an article in Nature Communications in which she shows that evolutionary changes within a human population can act rapidly on its size. The researcher used the population register (genealogical records) of île aux Coudres to determine the effect over a century of a genetic change - the change in the age of mothers at first reproduction - on the number of inhabitants on the island.

The grandmother effect

Dr. Pelletier is also interested in a particularity of our species - post-menopausal longevity. In nature, longevity and reproductive capacity are usually closely correlated. But in humans (and two whale species), women live well-beyond their reproductive age. This period of "infertility" might provide an evolutionary advantage, a hypothesis known as the grandmother effect. "Could there have been a natural selection which benefits families in which grandmothers could help mothers raise their children and thereby ensure larger families and thus a greater probability for the human species to develop?" asked the researcher.

Small difference, huge impact?

Throughout her projects. Dr. Pelletier raises questions about individual differences such as height or personality. Traditionally, researchers have considered large sets such as age cohorts and gender in order to understand demographic dynamics. "But individual differences can also influence a population's growth. Is it possible to quantify and measure the impact of these particularities?" asked the researcher, who accompanies a dozen students in their academic trajectories. In a period of major changes to society and behaviour, these questions are far from trivial.

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