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According to the reconstruction by Lahn and Page, the first step towards sex determination via DNA occurred roughly million years ago when one of the autosomes mutated and acquired the SRY gene--Sex-determining Region Y--which is the master switch for creating a male. Conference Beyond the Genome: The true gene count, human evolution and disease genomics.
Many genes on the human Y chromosome have homologues analogous genes on the X chromosome. Genes That is, we found little or no evidence of interchromosomal rearrangement, with the exception of rare events, e. The evolution of the sex chromosomes: Step by step October 28, Men and women, according to popular self-help books, hail from different planets, but what really separates them are radically different chromosomes.
Sex was not always determined by DNA.
Romanov, M. Indeed Uno et al. National Center for Biotechnology InformationU. External link. References 1. Schedule a Virtual Video Visit To request an appointment, please use our secure online form. Supplementary Data 4.
How did the sex chromosomes become so dissimilar? For help with Ingalls Care Connection, call us at or email portalsupport ingalls. Evolutionary biologists use sequence divergence as a clock: the longer two originally identical sequences have been isolated from one another, the more independent mutations they accumulate.