The Evolution of Tanning Needs Its Day in the Sun

Abstract

Variation in human pigmentation has been studied since the earliest days of biological anthropology.

Recent evolution of the human skin barrier

“…In contrast, Paik et al identified loci near GRM6 and ATF1 in a nomadic Mongolian population; these genes are involved in melanocyte signaling [38,39] . It has even been proposed that some populations primarily rely on the ability to tan, rather than dark constitutive pigment, to protect against harmful UV radiation [40] .…”

The evolution of human skin pigmentation involved the interactions of genetic, environmental, and cultural variables

“…Thus, most East Asian people can tan, whereas many Europeans, especially northern Europeans, can tan only slightly or not at all. The development and persistence of tanning abilities are conferred by many genes operating on melanin production, distribution, and breakdown in the skin (Del Bino et al., 2018 ) and tanning abilities, like depigmentation, have evolved multiple times independently in human history under conditions of seasonally strong UVR (Martínez‐Cadenas et al., 2013 ; Quillen, 2015 ; Quillen et al., 2019 ). The moderate tanning abilities among some Scandinavians and northern Europeans appear to have been conferred by recent genetic admixture across northern Eurasia (Hanel & Carlberg, 2020a ), but other factors, including altered epistatic interactions among pigmentation genes, may have also contributed.…”

Adaptation and co‐adaptation of skin pigmentation and vitamin D genes in native Americans

“…In other words, there is a substantial loss of correlation in America between skin color and UVR incidence, according to latitudes and altitudes, observed in other continents (Jablonski & Chaplin, 2000, 2010; Figure S1a), which is a notable exception to what is predicted by the "vitamin D-folate hypothesis." Some authors who advocate for the "vitamin D-folate hypothesis" believe that this phenotypic discrepancy in Native Americans may be due to their relatively recent arrival on the America continent (Adhikari et al, 2019;Jablonski, 2004;Juzeniene et al, 2009;Quillen, 2015;Rocha, 2020). Therefore, according to them, these populations might not have had enough time to adapt to the environments in which they live.…”

“…To build an overview more accurately, Jablonski and Chaplin (2000) compiled information and showed skin color data of Inuits from Greenland and four Native groups from South America. Despite this scarcity of work on the subject, Native Americans are often cited as exceptions to the distribution rule the skin color observed in other continental autochthonous groups (Adhikari et al, 2019; Aoki, 2002; Barsh, 2003; Byard, 1981; Deng & Xu, 2017; Diamond, 1991; Elias & Williams, 2013; Jablonski, 2004; Jablonski & Chaplin, 2000, 2010, 2013; Juzeniene et al, 2009; Murray, 1934; Quillen, 2015; Quillen et al, 2019; Robins, 1991; Rocha, 2020). For instance, comparing the skin color for Native Americans (Figure S1a) with the expected color prediction generated by a multiple regression model based on reflectance data (Figure S1b), there is a striking difference.…”

“…Some authors who advocate for the “vitamin D‐folate hypothesis” believe that this phenotypic discrepancy in Native Americans may be due to their relatively recent arrival on the America continent (Adhikari et al, 2019; Jablonski, 2004; Juzeniene et al, 2009; Quillen, 2015; Rocha, 2020). Therefore, according to them, these populations might not have had enough time to adapt to the environments in which they live.…”