Origins of life

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.

Evidence for life in 3.7-billion-year-old rocks appears to be crumbling away.

Life needs more than water alone. Recent discoveries suggest that plate tectonics has played a critical role in nourishing life on Earth. The findings carry major consequences for the search for life elsewhere in the universe.

A series of fossil finds suggests that life on Earth started earlier than anyone thought, calling into question a widely held theory of the solar system’s beginnings.

Evolution settled on a genetic code that uses four letters to name 20 amino acids. Synthetic biologists adding new bases to DNA will be free to improve on nature — if they can.

For decades, an origin-of-life story starring RNA has prevailed. New research may be shaking that theory’s hold on our understanding of life’s beginnings.

Which mattered first at the dawn of life: proteins or nucleic acids? Proteins may have had the edge if a theorized process let them grow long enough to become self-replicating catalysts.

Take chemistry, add energy, get life. The first tests of Jeremy England’s provocative origin-of-life hypothesis are in, and they appear to show how order can arise from nothing.

Life was long thought to obey its own set of rules. But as simple systems show signs of lifelike behavior, scientists are arguing about whether this apparent complexity is all a consequence of thermodynamics.