In 1956, ninety-six members of congress signed the southern manifesto which stated question 13 options: that the supreme court had violated the principle of states' rights. that the progressives of the south would labor to bring the region into the 20th century. that segregation was an acceptable institution. that congress should never pass civil rights measures.

that the supreme court had violated the principle of states' rights. --this was a reaction to the Brown v. Board of Education decision.

Brown v. Board of Education required desegregation of schools. The Southern Manifesto was a declaration of resistance to the decision. The congressmen that signed the document believed the decision was a reach by the Supreme Court and violated states' rights. 

Because the discoveries were some of the oldest human remains.