Hannibal crossed the Alps with a large army containing 37 war elephants in 218 BC. Details of his route have scholars ...

Contributed by John B. Goodenough, September 30, 2016 (sent for review August 24, 2016; reviewed by Ken Poeppelmeier and Jean-Marie Tarascon) ...

Fungi often transition between ecological roles, acting as pathogens, symbionts, and decomposers, yet the mechanisms enabling such lifestyle flexibility remain unclear. By comparing early and recently ...

Hamiltonian Systems and Transformation in Hilbert Space For more than 40 y, entomologists have attempted to estimate the number of insect species on Earth, with the current consensus—the figure most ...

The PNAS Editorial Board is made up of NAS members who are active scientists and experts in their fields. On submission, your paper is assigned to an Editorial Board member in one of the 31 NAS ...

The Democracy Index finding holds up best. Its negative direct effect on offensive VEI (we use β for SDM coefficients throughout) survives spatial adjustment in every bivariate specification (Table 1) ...

PNAS: Welcome to Science Sessions, the podcast of the Proceedings of the National Academy of Sciences, where we connect you with Academy members, researchers, and policymakers. Join us as we explore ...

Assembling the mitochondrial ATP synthase The assembly of the mitochondrial ATP synthase is a complicated process that involves the coordinated association of mitochondrially and nuclear encoded ...

Although theory and simulation of the MJO remain difficult challenges, they are guided by the generally accepted, fundamental features of the MJO (i.e., the MJO's “skeleton”) on ...

To help advance the species definition for prokaryotes, we have compared the gene content of 70 closely related and fully sequenced bacterial genomes to identify whether species boundaries exist, and ...

Most of the research papers in random graph theory concern the Erdős–Rényi model 𝒢p, in which each edge is independently chosen with probability p for some given p > 0 (see ref. 3). In such random ...

Birds, bees, lizards, elephants, and chimpanzees all share a survival trait: They self-medicate. These animals eat things that make them feel better, or prevent disease, or kill parasites like ...