Do Adults Keep Making New Brain Cells? Cold War-Era Radiation Reveals Answer

"When the U.S. and Soviet Union tested nuclear weapons aboveground in the 1950s and 1960s, they left their mark on everyone alive at that time. The tests released unusual amounts of carbon-14 into the atmosphere, which people's cells would sometimes incorporate into their DNA when they divided—whenever skin cells renewed themselves, for example, or hair strands grew one cell longer."