Study published in Nature Communications
Human evolutionary changes can impact population size
Sherbrooke, le 4 juillet 2017 – There is an often-heard claim that modern humans have stopped evolving as a result of the technological and cultural progress in the last few centuries. Recent scientific studies have revealed that it might not always be true. Indeed, in a study published in Nature Communications, Professor Fanie Pelletier and her collaborators from various universities have shown that human biological characteristics continue to evolve, and that those changes can have a significant impact on the size of human populations.
The researchers based this conclusion on detailed genealogical records of a contemporary human population. The data they used comes from the parish records of L'Île-aux-Coudres, which were meticulously maintained by the Catholic Church and the provincial government.
In an earlier study led by Professor Emmanuel Milot, the team observed that the age at which women had their first child (age at first reproduction) dropped from 26 to 22 years-old between 1800 and 1940, and one third of this change was due to genetics in response to natural selection. The current study— built upon this previous finding-— shows that this change in age at first reproduction influenced the growth and size of the population of L'Île-aux-Coudres.
"In studying a human population, we cannot ignore technological and cultural factors in the equation," pointed out Fanie Pelletier, professor in the Department of Biology at the Université de Sherbrooke. "We used data on the l'Île-aux-Coudres population because, for the years that we studied, the group was very homogeneous: Caucasian, French-speaking, and Catholic. The cultural pressures were the same, which is why we can use this data to assess the genetic evolution of the population. Moreover, it's important to note that cultural pressure can lead to a biological response."
Rapid Evolutionary Changes
Based on different demographic models, the researchers compared the actual growth rate of the population with a simulation in which the age at first reproduction was unaffected by genetic evolution. The population of L'Île-aux-Coudres increased nearly three-fold during the study period, and the research establishes that in absence of evolution, the population would have been 12% smaller.
"A common supposition in studying the dynamics of human populations is that evolution is slow and has minimal impact given the significant importance of non-evolutionary factors such as culture, wars, famine, and technological advances," added Gabriel Pigeon, a doctoral student in biology and co-author of the article. "Our results challenge this conventional viewpoint. Indeed, they suggest that this population's increase over 108 years can be explained, at least in part, by a genetic decrease in the age at first reproduction that occurred over the same period."
"What we can learn from this study is that evolutionary changes continue to occur in modern human populations and at a fairly rapid pace," added Professor Pelletier. "These changes can impact not only individuals but an entire population. It's important to study these changes in order to ultimately measure their effects."
The following universities collaborated to this study : Université de Sherbrooke, Bishop's University, Université du Québec à Montréal and Université du Québec à Trois-Rivières.
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For further information:
Judith Lavallée, Media-Relations Officer, Communications Department | Université de Sherbrooke, 819-821-8000, extension 65472medias@USherbrooke.ca