Interbreeding between archaic and modern humans been shown that Neanderthal ancestry has been selected against in conserved biological pathways, such as RNA processing. Consistent with the hypothesis that purifying selection has reduced Neanderthal contribution in present-day modern human genomes, Upper Paleolithic Eurasian modern humans (such as the Tianyuan modern human) carry more Neanderthal DNA (about 4–5%) than present-day Eurasians modern humans (about 1–2%). Genes affecting keratin were found to have been introgressed from Neanderthals into modern humans (shown in East Asians and Europeans), suggesting that these genes gave a morphological adaptation in skin and hair to modern humans to cope with non-African environments. This is likewise
The Keg of Nails is a replica of a keg used to ship nails. The exchange is believed to have been initiated by fraternity chapters on the UC and U of L campuses, signifying that the winning players in the game were "tough as nails." The present keg is actually a replacement for the original award, which was misplaced by Louisville, lost during some construction of office facilities. It is adorned with the logos of both schools and the scores of the series games. The rivalry went on hiatus following the 2013 season, as Louisville moved to the Atlantic Coast Conference on July 1,