Abstract: Transposable Elements are biologically important components of eukaryote genomes. In particular, non-LTR retrotransposons (N-LTRrs) extensively shaped the human genome throughout evolution. In this study, we compared retrotransposon insertions differentially present in the genomes of Anatomically Modern Humans, Neanderthals, Denisovans and Chimpanzees, in order to assess the possible impact of retrotransposition in the differentiation of the human lineage. Briefly, we first identified species-specific N-LTRrs and established their distribution in present day human populations. These analyses shortlisted a group of N-LTRr insertions that were found exclusively in Anatomically Modern Humans. Notably, these insertions targeted genes more frequently than randomly expected and are associated with an increase in the number of transcriptional/splicing variants of those genes they inserted in. The analysis of the functionality of genes targeted by human-specific N-LTRr insertions seems to reflect phenotypic changes that occurred during human evolution. Furthermore, the expression of genes containing the most recent N-LTRr insertions is enriched in the brain, especially in undifferentiated neurons, and these genes associate in networks related to neuron maturation and migration. Additionally, we also identified candidate N-LTRr insertions that have likely produced new functional variants exclusive to modern humans, which show traces of positive selection and are now fixed in all present-day human populations. In sum, our results strongly suggest that N-LTRr impacted our differentiation as a species and have been a constant source of genomic variability all throughout the evolution of the human lineage. (public access) – Etienne Guichard, Valentina Peona, Guidantonio Malagoli-Tagliazucchi, Lucia Abitante, Evelyn Jagoda, Margherita Musella, Marco Ricci, Alejandro Rubio-Roldán, Stefania Sarno, Donata Luiselli, Davide Pettener, Cristian Taccioli, Luca Pagani, Jose Luis Garcia-Perez, Alessio Boattini
And each and every accidental change was a benefit? Wow. There must be a lot of extinct species out there that we haven’t found yet, for which the change didn’t work.
See also: Jumping’ Genes!: A quarter of cow DNA came from reptiles? If jumping genes can be this prevalent, evolution is about to become way more complex than the storied Tree of Life hammered into kids at school. They could be like migrating populations.