Archaeans

The clearest picture yet of our “last universal common ancestor” suggests it was a relatively complex organism living 4.2 billion years ago, a time long considered too harsh for life to flourish.

All modern multicellular life — all life that any of us regularly see — is made of cells with a knack for compartmentalization. Recent discoveries are revealing how the first eukaryote got its start.

Cells across the tree of life can swap short-lived messages encoded by RNA — missives that resemble a quick text rather than a formal memo on letterhead.

As researchers race to cultivate more of the intriguing cells from the deep seafloor, the few cells now growing in labs are giving us our best glimpses of the forerunners of all complex life.

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?

Scientists have reported large DNA structures in some archaea that defy easy categorization.

New work shows that histones, long treated as boring spools for DNA, sit at the center of the origin story of eukaryotes and continue to play important roles in evolution and disease.

An unorthodox symbiotic theory about the origin of eukaryotes’ defining characteristic may soon be put to the test.

New studies revise ideas about the symbiosis that gave mitochondria to cells and about whether the last common ancestor of all eukaryotes was one cell or many.