As artificial intelligence spreads, millions of middle-class jobs in human resources, billing and payroll could be at risk. Most are held by women.

© Timo Lenzen

Elon Musk’s potential new status as a trillionaire demonstrates in real time why there has been such a rapid rise in the concentration of wealth at the top.

© Nicolas Ortega

Modern smartphones rolled out in 2007, the year that fertility rates began falling. Two studies say that is not a coincidence.

© Colin Clark for The New York Times