Race and health refers to how being identified with a specific race influences health. Race is a complex concept that has changed across chronological eras and depends on both self-identification and social recognition. In the study of race and health, scientists organize people in racial categories depending on different factors such as: phenotype, ancestry, social identity, genetic makeup and lived experience. "Race" and ethnicity often remain undifferentiated in health research. Differences in health status, health outcomes, life expectancy, and many other indicators of health in different racial and ethnic groups are well documented. Epidemiological data indicate that racial groups are unequally affected by diseases, in terms or morbidity and mortality. Some individuals in certain racial groups receive less care, have less access to resources, and live shorter lives in general. Overall, racial health disparities appear to be rooted in social disadvantages associated with race such as implicit stereotyping and average differences in socioeconomic status. Health disparities are defined as "preventable differences in the burden of disease, injury, violence, or opportunities to achieve optimal health that are experienced by socially disadvantaged populations". According to the U.S. Centers for Disease Control and Prevention, they are intrinsically related to the "historical and current unequal distribution of social, political, economic and environmental resources". The relationship between race and health has been studied from multidisciplinary perspectives, with increasing focus on how racism influences health disparities, and how environmental and physiological factors respond to one another and to genetics. Racial health disparities Health disparities refer to gaps in the quality of health and health care across racial and ethnic groups. The US Health Resources and Services Administration defines health disparities as "population-specific differences in the presence of disease, health outcomes, or access to health care". Health is measured through variables such as life expectancy and incidence of diseases. For racial and ethnic minorities in the United States, health disparities take on many forms, including higher rates of chronic disease, premature death, and maternal mortality compared to the rates among whites. It is important to note that this pattern is not universal. Some minority groups—most notably, Hispanic immigrants—may have better health outcomes than whites when they arrive in the United States. However this appears to diminish with time spent in the United States. For other indicators, disparities have shrunk, not because of improvements among minorities but because of declines in the health of majority groups. In the