Our lay concept of race is a social construct that has been laid on top of these vastly more complex biological realities. That is not to say that socially defined race is meaningless or useless. (Modern genomics can do a good job of determining where in Central Europe or Western Africa your ancestors resided.) However, a willingness to speak casually about modern racial groupings as simplifications of the ancient and turbulent history of human ancestry should not deceive us into conjuring back into existence 19th-century notions of race — Caucasoid, Negroid, Mongoloid, and all that.
Murray talks about advances in population genetics as if they have validated modern racial groups. In reality, the racial groups used in the US — white, black, Hispanic, Asian — are such a poor proxy for underlying genetic ancestry that no self-respecting statistical geneticist would undertake a study based only on self-identified racial category as a proxy for genetic ancestry measured from DNA.