The evolutionary role of human-specific genomic events

• Main Author: Itan, Y.
• Published: University College London (University of London) 2010
• Subjects: 500
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564807

In the short evolutionary time since the human-chimpanzee divergence, approximately 6.6 million years ago, humans have acquired a range of traits that are unique among primates. These include tripling brain size, enhanced cognitive abilities, complex culture, descended larynx structure that enables spoken language, longevity, specific diseases, inferior olfaction, and (in some human populations) adult lactase persistence. These traits were likely to have evolved through various genomic mechanisms, among them gene duplications and gene-culture co-evolution. Several studies have estimated the dates for some of these human lineage genomic events. However, no study to date has performed a genomewide estimate of the dates of all human gene duplications. Moreover, as many of these traits were likely to have evolved via gene-culture coevolutionary mechanisms, investigating the evolution of one of these human-specific traits – lactase persistence – provides a model example for in-depth future investigations of specific human phenotypes. In this study I have investigated an important class of human-specific genomic events – gene duplications (otherwise known as human inparalogues). I have developed a new bioinformatics approach for detecting human lineage-specific inparalogues and the duplication dates for those genes. I show that human-specific inparalogues are non-randomly distributed among biological function classes, and their duplication event dates are non-randomly distributed on a timeline between the date of the human-chimpanzee split and the present. I have also investigated the evolution of the human-specific polymorphic trait – lactase persistence. I have performed a worldwide correlation analysis comparing frequency data on all currently known lactase persistence-associated alleles and the distribution of the lactase persistence phenotype in different human populations. I have also performed a gene-culture co-evolution analysis, employing spatially explicit simulation and Approximate Bayesian Computation to condition simulations on genetic and archaeological data, in order to make inferences on the evolution of lactase persistence and dairying in Europe.