A research team led by biogeochemists at the University of
California, Riverside has tested a popular hypothesis in paleo-ocean chemistry,
and proved it false.
The fossil record indicates that eukaryotes — single-celled
and multicellular organisms with more complex cellular structures compared to
prokaryotes, such as bacteria — show limited morphological and functional
diversity before 800-600 million years ago. Many researchers attribute the
delayed diversification and proliferation of eukaryotes, which culminated in
the appearance of complex animals about 600 million years ago, to very low
levels of the trace metal zinc in seawater.