Human Migration Genetic Diversity and Race

Since its genesis in the sixteenth century, the concept of race as a biological kind has been a focal point of debate (Boxill). Controversy over the use of the term has emerged in regard to the values that have been attached to groups identified by race and the characteristics that have been attributed to them. Throughout the twentieth century scholars consistently challenged the validity of biological differences between populations that were linked to race. Scientific research consistently has revealed that more genetic variation exists within than between populations (Lewontin). Despite this finding, race has become increasingly salient in understanding disparities in the health status of population groups and continues to be an important factor in both biomedical research and clinical medicine.

Central to arguments over race is a lack of agreement on its definition. In a manner that often is implicit, biomedical researchers and clinicians use a potpourri of surrogate concepts, including skin color, hair type, national origin, and citizenship, to identify race. This situation is complicated by the common practice of relying on self-reports, which often are based on factors that have little to do with biology. In addition, racial categories change over time and tend to be context-dependent, as is illustrated by the history of U.S. Census racial and ethnic categories (Lee et al.). Since the insertion of the term race into scientific discourse, the definition of race has been a moving target, and this has contributed to confusion about its meaning and implications for biomedical research and clinical care.

In 1996 the American Association of Physical Anthropologists issued a statement that included the following assertion: "Pure races, in the sense of genetically homogenous populations, do not exist in the human species today, nor is there any evidence that they have ever existed in the past." Although it acknowledges that differences between individuals exist, the statement emphasizes that those differences are the result of hereditary factors and the effects of natural and social environments. Genetic differences between populations result from the effect of the history of human migration and reproduction and consist of a gradient of varying frequencies of all inherited traits, including those that are environmentally malleable.

Critical to comprehending human genetic variation is an understanding of the meaning of population genetic structure, which is best understood as the pattern of genetic differences among genomes, the full sets of human genes found in the nucleus of each cell. These genes are arranged linearly on chromosomes and consist of strings of chemical units called nucleotides (Weiss). The genome interacts with the environment to produce phenotypes, or all observable traits of individual appearance and behavior. Patterns within the genome vary across a species, depending on the history of mating within that species. The patterns or genetic frequencies of human populations have been affected by mutation, migration, natural selection, and random genetic drift to varying extents. These forces have resulted in the genetic variation that exists among human populations. Genetic differences between global populations do not map neatly onto the racial categories that have emerged through sociohistorical processes. Instead, race, defined by discrete group boundaries, serves as a poor proxy for the continuum of human genetic variation.

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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