When Norwegian researchers
brought up a mud core from
the floor of the Atlantic Ocean
in 2010, they were orchestrating a
family reunion. After 2 billion years
of separation, a descendant of our
distant common ancestor, a simple
microorganism, has been discovered in
the sediment by molecular biologists at
Uppsala University in Sweden.
All nonviral life on Earth belongs
to one of three domains. Complex
organisms, distinguished by nucleated
cells, collectively belong to Eukarya.
The other two domains, genetically
different yet both structurally simple,
are Bacteria and Archaea. One of the
great puzzles in biology is how simple
life evolved to become complex. The
Archaean discovered under the Atlantic
— dubbed Lokiarchaeota in Nature in
May — appears transitional, showing
an unprecedented degree of genetic
overlap with eukaryotes.