Life of the Oceans - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 138

fig. 12. Bangiomorpha is a possible red alga from rocks 1.2 billion years old in
Arctic Canada. It shows the earliest fossil evidence for sexual reproduction. The
scale bar is 200 microns, one-fifth of a millimetre.
Building the First Bodies
Bodies can do so much more than single cells. They can build three-
dimensional structures with tissues, and make shapes that encourage
the flow of water (and nutrients) over those tissues. They can make
mouths and guts to specialize in feeding, and they can build fins and
legs for locomotion to take the organism to its food. Once cells began
to cooperate in a single construction, albeit very simply at first,
Darwinian evolution could operate to select for structures and speci-
alities that confer some advantage. For multicellular life to progress,
though, Darwinian evolution must act to favour some cells becoming