Jan Sapp reviews the evidence in two new books on the topic:

[N]ot only are the differences between the classically defined "races" very superficial, they are also of surprisingly recent origin; the variety of human populations seems to have both accumulated and begun to reintegrate within the past 50,000 to 60,000 years. The diversity among us has arisen in a blink of evolution’s eye. The process of relative geographic isolation of local populations into what might have been true races (genetically differentiated populations) during the last Ice Age began to reverse as formerly isolated human groups came back into contact and interbred. That reintegration, which has occurred intermittently throughout human history, is sped up today because of great migration and widespread mating of individuals from disparate geographic origins. The result is that individuals identified as belonging to one “race,” based on the small number of visible characters used in historical race definitions, are likely to have diverse ancestry. 

Jerry Coyne responds that "if that's the consensus, then I am an outlier":