His study, based in Chicago, has challenged an immensely popular competing theory about the roots of crime.

The study, which will be published later this month, challenges the Pentagon's assessment of future military threats as unrealistic.

Recent studies challenge the claims that bride kidnapping used to be prevalent.

Recent studies have challenged the idea that Andeans are 'a people without history'.

At least one study has challenged the existence of the gender gap in mathematics.

The study also challenged the notion that lower Government spending leads to higher personal giving.

The work is an important correction of some data in the field, "but I don't think the studies fundamentally challenge the self-nonself theory."

By emphasizing the influence of family background, the studies not only challenge American identity but speak to the debate about inequality.

The new study is also challenging the most prominent hypothesis of how rain forest species evolved.

However, later study challenged the universality of the successive capture theory.