Understanding skin color variations as an adaptation by detecting gene-environment interactions

Genetic and environmental factors influence the elaborate feedback mechanism that enables the human adaptive form to make internal adjustments in response to environmental stimuli. Human survival may ultimately depend on research elucidating the complex dynamics of the human genome, as well as an understanding of how environmental pressures affect the genome and influence human traits. This chapter reviews our present knowledge of the mechanisms by which haplotypes comprising multiple single-nucleotide polymorphisms (SNPs) can contribute to differences between human population groups. Herein, we describe current approaches to detecting natural selection in pigmentation candidate genes on the basis of haplotypes revealed by SNP analyses. This chapter also discusses methods for elucidating the selective genetic mechanisms that have operated to alter human skin pigmentation, which may be induced by ultraviolet radiation (UVR) in the birthplaces of human populations. Finally, we present our recommendation of spatial statistical methods for clarifying gene-environment interactions, as applicable to interactions with UVR levels. Spatial statistical approaches that apply environmental association rules can be used to extend our knowledge of human adaptation to the environment.