Pnas Science Sessions

Mohammad Reza Alizadeh, John T. Abatzoglou, and Mojtaba Sadegh report that forest fires have been advancing upslope across the western United States in recent decades.

Eran Amichai investigates how bats know the speed of sound.

Mike Gil discusses how changes in animal behavior can affect ecosystems.

Brad Greenwood explains how patient–physician racial concordance decreases Black infant mortality.

Vinay Pathak describes when and where HIV sheds its capsid coating while infecting human cells.

Jeannie Lee describes the discovery of self-cleaving ribozymes.

Josh Bongard describes AI-designed, reconfigurable biological organisms made from frog cells.

Jonathon Yuly, David Beratan, and Peng Zhang investigate how electron bifurcation reactions work.

Adam Mastroianni and Daniel Gilbert explore why conversations almost never end when people want them to.

Joe Levy shows how glaciers on Mars can reveal its climate history.

Marianne Alleyne, Aimy Wissa, and Ophelia Bolmin explain how the click beetle amplifies power to pull off its signature jump.

Mara Reed and Michael Manga explore why Yellowstone's Steamboat Geyser resumed erupting in 2018.

Martin Bizzarro tells what zircon crystals reveal about the geological history of Mars.

Aleix Martinez explains why facial expressions often are not accurate indicators of emotion.

Amanda Rodewald, Ivan Rudik, and Catherine Kling talk about the hazards of ozone pollution to birds.

Se-Jin Lee and Emily Germain-Lee explain a way to preserve bone and muscle mass during spaceflight.

David Crowder and Gengping Zhu explain how to predict the spread of the Asian giant hornet.

Brian Fields explores a hypothesis that a supernova may be responsible for a mass extinction.

Eric Horvitz discusses AI’s promises and perils.

Juliana Vianna and Rauri Bowie explain the origin and diversification of penguins.