The first organisms on Earth appeared approximately 3.8 billion years ago and were all unicellular. Multicellular organisms have only existed for about one billion years.
What evolutionary milestone made it possible for more complex, multicellular organisms to exist?
A.
appearance of prokaryotic cells
B.
appearance of eukaryotic cells
C.
appearance of stem cells
D.
appearance of photosynthetic cells
B. appearance of eukaryotic cells
Eukaryotic cells, with their more complex internal structures and membrane-bound organelles, allowed for greater specialization of cells within an organism and eventually led to the evolution of multicellular organisms.