Further support for the evolutionary role of ADH1 genes is provided by investigations of primate evolution. Although there is still an open debate, primates showed multiple independent gene conversions among ADH1 paralogous genes in marmoset, macaque, and human lineages [Carrigan and others 2012]. Analyzing ADH1B cDNA from mouse, chimpanzee, and human samples, the synonymous and non-synonymous substitution (dN/dS) ratios was significantly low in all pairs, suggesting the presence of purifying selection [Oota and others 2007]. This supports that the ADH1 system was evolutionarily selected to be highly efficient, most obviously to permit a higher consumption of fermented fruits.
