ABSTRACT
Pelage (i.e., hair/fur) is one of the most salient traits of terrestrial mammals, providing protection, insulation, and camouflage. Pelage is well genetically characterized and is also the product of selection, making it an excellent trait to study evolutionary processes. Primates are highly variable in their hair phenotypes—exhibiting distinct coloration (i.e., reds, stripes) and hair growth (i.e., mustaches, long capes). Primate pelage—including human hair—varies within and across populations and individuals. These pattern variations are largely associated with ecology, sex, and age. However, we do not yet have a firm understanding of the genetic and cellular mechanisms driving primate hair diversity. We can, though, use what is known from research on laboratory and domesticated species to guide our hypotheses. In such cases, hair melanogenesis and keratinization occur within the hair follicle and involve two distinct cellular cascades and a variety of genes. Selection acting on both processes can be impacted by rapid ecological change. In this chapter, we review the pathways of hair melanogenesis and keratinization and highlight key candidate genes worthy of further study. By combining molecular and cellular techniques with hair phenotyping, primatologists can answer fundamental questions about biology than spans behavior, ecology, signaling, and biodiversity.
