evolution

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?

Large blocks of genes conserved through hundreds of millions of years of evolution hint at how the first animal chromosomes came to be.

Studies that map the adaptive value of viral mutations hint at how the COVID-19 pandemic might progress next.

New studies reveal the ancient, shared genetic “grammar” underpinning the diverse evolution of fish fins and tetrapod limbs.

The detailed understanding of brains and multicellular bodies reached new heights this year, while the genomes of the COVID-19 virus and various organisms yielded more surprises.