Death rates in the 20th century fever, polio, measles, hepatitis among others. However, war, genocide and Holocausts have led to many millions of deaths throughout the century, and late in the century AIDS had already killed millions, particularly in Africa and south-east Asia. Cancer also killed millions via lifestyle and pollution generated by increased work in factories. During the 20th century, an enormous improvement in public health led to an overall decrease in death rates. Infant mortality rates and maternal mortality rates have dramatically decreased. In the early 1900s, 6-9 women died in pregnancy-related complications for every 1,000 births, while 100 infants died before they were
American social dancing in the 20th century to big band music, while jazz dance was done to jazz music. The 20th century brought about a change in social dances. The "old fashioned and out of step" dances such as "the waltz and polka" needed to make way "for something different and new". In the past, only upper class dances had been recorded because lower class dances were "not deemed worthy of record". However, now in the 20th century, "the Industrial Age was upon us, a new middle class was emerging and great social ... innovations were on the horizon". The upper class even became more accepting of