HHU biologists find evidence for two independent origins of life
This digest was compiled by AI from multiple sources — links to the originals are below.
Biologists at Heinrich Heine University Düsseldorf report in Science Advances on August 12 that the first free-living cells may have emerged independently twice. The international team compared genomes, protein structures and 420 metabolic reactions conserved across bacteria and archaea. The findings challenge the assumption that cellular life arose once from a single free-living ancestor.
Two Pioneer Cell Types
The study, published in Science Advances on August 12, reconstructs the earliest split between bacteria and archaea. Lead author Natalia Mrnjavac, a biologist at Heinrich Heine University Düsseldorf, said the scene about 4 billion years ago would show two very different kinds of cells emerging. She described 'pioneer bacteria and pioneer archaea' making their first attempts at life outside the confines of a hydrothermal vent.
The 420-Reaction Metabolic Core
The HHU-led team examined all 420 chemical reactions that cells use to manufacture amino acids, RNA bases and vitamins from early-Earth materials such as hydrogen gas, ammonia and CO2. Senior author William Martin said the comparisons allow reconstruction of the phase when enzyme-catalyzed metabolism arose from metal-catalyzed reactions in Earth's crust. The reactions themselves are ancient and conserved across life to a degree comparable with the genetic code.
Enzyme Conservation Gap
The researchers found that the enzymes responsible for carrying out those 420 reactions do not show the same degree of conservation between bacteria and archaea. This divergence suggests the first free-living cells may have emerged independently twice. The study involved an international team led by biologists in Düsseldorf.
What's Next
The HHU team's two-origins model now faces testing against geochemical evidence from early Earth hydrothermal systems. It remains unclear whether the shared genetic code reflects a single ancestral population or convergence after two independent starts.
1 source
HHU biologists find evidence for two independent origins of life
