By the 1900s, nigger had become a pejorative word in the United States. In its stead, the term colored became the mainstream alternative to negro and its derived terms. After the African-American Civil rights movement, the terms colored and negro gave way to "black". Negro had superseded colored as the most polite word for African Americans at a time when black was considered more offensive. This term was accepted as normal, including by people classified as Negroes, until the later Civil Rights movement in the late 1960s. One well-known example is the identification by Reverend Martin Luther King, Jr. of his own race as "Negro" in his famous speech of 1963, I Have a Dream. During the American Civil Rights movement of the 1950s and 1960s, some African-American leaders in the United States, notably Malcolm X, objected to the word Negro because they associated it with the long history of slavery, segregation, and discrimination that treated African Americans as second-class citizens, or worse. Malcolm X preferred Black to Negro, but later gradually abandoned that as well for Afro-American after leaving the Nation of Islam.
When did "nigger" become a pejorative word?
By the 1900s

The new Kievan state prospered due to its abundant supply of furs, beeswax, honey, and slaves for export, and because it controlled three main trade routes of Eastern Europe. In the north, Novgorod served as a commercial link between the Baltic Sea and the Volga trade route to the lands of the Volga Bulgars, the Khazars, and across the Caspian Sea as far as Baghdad, providing access to markets and products from Central Asia and the Middle East. Trade from the Baltic also moved south on a network of rivers and short portages along the Dnieper known as the "route from the Varangians to the Greeks," continuing to the Black Sea and on to Constantinople. Kiev was a central outpost along the Dnieper route and a hub with the east-west overland trade route between the Khazars and the Germanic lands of Central Europe. These commercial connections enriched Rus' merchants and princes, funding military forces and the construction of churches, palaces, fortifications, and further towns. Demand for luxury goods fostered production of expensive jewelry and religious wares, allowing their export, and an advanced credit and money-lending system may have also been in place.
Which route was a central post in Kiev?
Dnieper route

The major landmark of puberty for males is the first ejaculation, which occurs, on average, at age 13. For females, it is menarche, the onset of menstruation, which occurs, on average, between ages 12 and 13. The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well. Regardless of genes, a girl must have a certain proportion of body fat to attain menarche. Consequently, girls who have a high-fat diet and who are not physically active begin menstruating earlier, on average, than girls whose diet contains less fat and whose activities involve fat reducing exercise (e.g. ballet and gymnastics). Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages.
Besides heredity, what other factors contribute to when menustration begins?
diet and lifestyle