The concept of race as a rough division of human population has a long and complicated history. The word race itself is modern and was used in the sense of "nation, ethnic group" during the 16th to 19th century, and only acquired its modern meaning in the field of physical anthropology from the mid 19th century. The politicization of the field under the concept of racism in the 20th century has led to a decline in racial studies during the 1930s to 1980s, culminating in a poststructuralist deconstruction of race as a social construct. Since the 1990s, there has been renewed interest in questions of race and genetics and the study of phenotypic and genetic variability, and the quantitative study of genetic clustering.