The mighty Mississippi is shackled and constrained by a series of channels, locks, and levees. The height of those levee walls is regulated by the Army Corps of Engineers to ensure that riverside districts equally bear the risk of flooding. But some districts have piled more sand atop their levees to protect against imminent flood risk during emergency conditions—and then left those sandbags there after the danger passed, leaving a system of levees with irregular heights. A team of investigative reporters at ProPublica has shown that those higher levee walls protect the people and developments behind them, but shift the risk of flooding onto neighboring communities who have followed the rules.

A new study reported in Cell Stem Cell this week found evidence of new neurons and their stem cell progenitors in brains as old as 79, some with numbers of neurons on par with younger brains. Columbia University neurobiologist and study author Maura Boldrini describes the work, and why we’re still resolving questions about aging brains.

Not all farts are created equal—some animals don’t have the affinity for flatus, while others use their stench strategically. Zoologist Dani Rabaiotti and ecologist Nick Caruso, authors of the book Does It Fart? The Definitive Field Guide to Animal Flatulence, discuss how there really is much more to flatology (the study of flatulence) once you get a closer whiff.