Rolf Degen summarizes: Contrary to earlier believes, humans have at least as many - if not more - Olfactory Receptor genes as monkeys and apes, with color vision being no limiting factor

Evolution of Genes for Color Vision and the Chemical Senses in Primates. Shoji Kawamura, Amanda D. Melin. Chapter in Evolution of the Human Genome I. https://link.springer.com/chapter/10.1007/978-4-431-56603-8_10

Abstract: Primates are generally regarded as visually oriented mammals, trading a sense of smell for good sight. However, recent studies have questioned this simplistic view, and it is not well understood the extent to which senses have evolved interactively or in concert with each other in primates including humans. For example, the number of olfactory receptor genes is not as clearly differentiated between species with different color vision as once asserted. Among senses, receptors of stimuli for vision, olfaction, and bitter/sweet/umami tastes all belong to the G-protein-coupled receptor (GPCR) family, for which the genetic mechanism of signal perception is well understood. Thus, it is now possible to explore the evolutionary correlation among different senses in primates by studying these receptor groups for interspecies divergence, intraspecies diversity, and functional differences among variants. In this chapter, we review recent findings on these receptors and senses in humans and other primates and discuss the future directions of studies on their sensory evolution.



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