Scientists find origin of Earth's earliest life to 4.2 bn yrs ago

Researchers from University of Bristol studied Earth's earliest ecosystem to determine when life began flourishing, about 100 million years after formation. They traced the Last Universal Common Ancestor (LUCA), thought to be all modern cellular life's origin, to 4.2 billion years ago. They compared genes across species, counting mutations and using fossil records to pinpoint LUCA's existence.