In a 2007 review paper, Štrkalj suggested that the stark contrast of the racial approach between the United States and China was due to the fact that race is a factor for social cohesion among the ethnically diverse people of China, whereas "race" is a very sensitive issue in America and the racial approach is considered to undermine social cohesion - with the result that in the socio-political context of US academics scientists are encouraged not to use racial categories, whereas in China they are encouraged to use them