Although this issue has been argued since the 1870s—when Francis Galton proposed his controversial and arguably racist notions about the heritability of intelligence—the debate was reignited during the 1990s when Richard Herrnstein (1930–94) and Charles Murray (1943–) published The Bell Curve: Intelligence and Class Structure in American Life (New York: Touchstone Books, 1996). Herrnstein and Murray expressed their beliefs that between 40% and 80% of intelligence is determined by genetics and that it is intelligence levels, not environmental circumstances, poverty, or lack of education, that are at the root of many of our social problems. Critics argued that Herrnstein and Murray not only manipulated and misinterpreted data to support their contention that intelligence levels differ among ethnic groups, but also reintroduced outdated and harmful racial stereotypes. Many observers did agree with Herrnstein and Murray's premises that intellect is spread unevenly among individuals and population subgroups, that innate intelligence is distributed through the entire population on a "bell curve," with most people near to the average and fewer at the high and low ends, and even that the distribution varies by race and ethnicity. But few have been willing to accept the idea that intelligence is entirely genetically encoded, permanently fixed, and unresponsive to environmental influences.