Evolution

Without a good definition of life, how do we look for it on alien planets? Steven Strogatz speaks with Robert Hazen, a mineralogist and astrobiologist, and Sheref Mansy, a chemist, to learn more.

The lush biodiversity of the Amazon may be due in part to the dynamics of branching rivers, which serve as invisible fences that continuously barricade and merge bird populations.

Some animal neuropeptides have been around longer than nervous systems.

When researchers gave a genetic molecule the ability to replicate, it evolved over time into a complex network of “hosts” and “parasites” that both competed and cooperated to survive.

Was the addition of mitochondria a first step in the formation of complex cells or one of the last? A new study of bacteria tries to answer this contentious question in evolutionary biology.

Traits from RNA molecules passed between multiple generations of worms can work with genetic changes to influence future evolution.

The optical properties of mitochondrial bundles in the retina may improve how efficiently the eye captures light.

Biomechanical interactions, rather than neurons, control the movements of one of the simplest animals. The discovery offers a glimpse into how animal behavior worked before neurons evolved.

Molecular detective work is zeroing in on the origins of sexual reproduction. The protein tools for cell mergers seem to have long predated sex — so what were they doing?