The question of the origins of our species has intrigued humans since their appearance on earth, and they seek to answer it through religion, philosophy, art, history or science. One branch of biology that addresses this question is population genetics. Population genetics studies healthy individuals, not sick individuals ; it studies human populations, all descended from the first humans to leave Africa, descended from those who survived famines, descended from those who resisted numerous diseases, such as tuberculosis, the Black Death or Spanish flu. The study of the genetic diversity of these individuals thus forms the basis of population genetics.
From the very beginning of modern genetics, four major factors were identified as influencing genetic variability : mutation, which produces new genetic types; natural selection, which favors genetic types that give individuals a better adaptation to the environment in which they evolve; genetic drift, which is the effect of chance due to fluctuations in genetic type frequencies from one generation to the next; and migration. However, demographic and selective processes are difficult to distinguish, as they can have identical effects on genetic variability. For example, natural selection and population history can mimic each other in the molecular signatures left on genome variability : a recent expansion of a population may produce a signal that could be confused with that of a selective sweep (positive selection) at the level of a gene.
The lecture " Human Genomics and Evolution " aims to show how advances in knowledge about genome variability at the level of human populations and the various factors that shape this variability are helping to understand human demographic history, adaptation to the environment, and the relationships between genetic diversity and phenotypic diversity, whether benign or disease-causing. Topics to be covered include (i) introduction to population genetics, (ii) genetic and phenotypic diversity in humans, (iii) genetic reconstruction of the demographic history of our species, (iv) natural selection and adaptive phenotypes, (v) genetic diversity and cultural forces, and (vi) human adaptation to pathogens : immunity and infectious diseases.