Even though browns/mulattos and blacks comprise more than 50 percent of the population, they comprise less than 25 percent of elected politicians. A 2016 study, using twins as a control for neighborhood and family characteristics, found that the nonwhite twin is disadvantaged in the educational system. A 2015 study on racial bias in teacher evaluations in Brazil found that Brazilian math teachers gave better grading assessments of white students than equally proficient and equivalently well-behaved black students. A 2018 paper found that discriminatory hiring and retention policies accounted for 6-8% of the overall racial wage gap. In Chile, there is a wide range of diversity from other cultures and ethnic backgrounds. The diversity in Chile sees colorism through social-economic status, accommodating the preexisting notion that darker skin complexions are less valued. A 2016 study found that Chilean schoolteachers had lower expectations of their dark-skinned students ("morenos") than their light-skinned students ("blancos"). Even differences between being dark and being tanned carry different types of statuses, whereas being tanned means more money as they have time to go to the beach or buy tanning products, while the history of colonization automatically attributes darker skin as being lower class. Current studies have been finding that many Chileans favor to be lighter in pigmentation and even perceive themselves to be White despite a mixture of skin tones. A 2017 study revealed a 45% gap in educational achievement between the darkest- and lightest-skinned White Mexicans and that wealth in the country similarly correlated to skin color. European colonialism created a system of racial hierarchy and a race-based ideology, which led to a structure of domination that privileged whites over blacks. Biological differences in skin color were used to justify the enslavement and oppression of Africans and Native Americans, leading to the development of a social hierarchy that placed whites at the top and blacks at the bottom. Slaves with a lighter complexion were allowed to engage in less strenuous tasks, like domestic duties, while darker-skinned slaves participated in hard labor, which was more than likely done outdoors. African-Americans with a partial white heritage were seen to be smarter and superior to dark-skinned blacks, and as a result, they were given broader opportunities for education and the acquisition of land and property. While there is evidence that races have on average differences in IQ, this does not take into account historic academic disadvantages and widespread educational and societal systemic oppression faced by certain races. Colorism was a device used by the white colonists in order to create a division between the Africans and further the idea that being as close to white as possible was the ideal image.