L'ADN mitochondrial, le chromosome Y et l'histoire des populations humaines.

Abstract

De nombreuses disciplines etudient les origines de l' espece humaine. En particulier, l' archeologie, l' anthropologie, la linguistique et la paleontologie tentent de retracer les grandes etapes de notre passe. Plus recemment, la genetique et la biologie moleculaire ont permis de preciser l' origine des differentes populations humaines en etudiant les variations genetiques entre les individus. Parmi tous les marqueurs genetiques utilises, les plus interessants sont les marqueurs uniparentaux comme l' ADN mitochondrial, herite de la mere, et le chromosome Y, herite du pere car ils echappent tous deux a la recombinaison meiotique. Ainsi, contrairement aux autosomes ou au chromosome X, tous les ADN mitochondriaux presents dans les populations humaines peuvent provenir d' un ancetre maternel commun et les chromosomes Y, d' un ancetre paternel commun. Ces deux marqueurs ont donc ete utilises pour preciser geographiquement et historiquement l' origine de nos ancetres communs les plus recents et les interactions entre les differentes populations humaines.

Many disciplines such as archaeology, anthropology, linguistic and paleontology are involved in the study of human origins. More recently, genetics and molecular biology have been used to shed light on human origins. For many years, geneticists have studied the DNA variations among individuals and populations in order to establish relationships between different populations. Of the DNA markers available, the most interesting are the uniparental inherited markers, which are the maternally inherited mtDNA and the paternally inherited Y-chromosome. They both escape from regular recombinational processes at meiosis and, consequently, these markers are transmitted together as haplotypes preserving a unique record of mutational changes that have occurred in previous generations. While X chromosomes and autosomes each have multiple ancestors because of recombination, all modern mtDNAs could have a single maternal ancestor and Y-chromosomes could have a single paternal ancestor. Here we review the general characteristics of the Y chromosome and the mtDNA and, using specific examples, we show how haplotypes can be used to determine human origins and study different population interactions in historical times.