Life of the Oceans - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 135

long interval of time of the early Proterozoic (the 'boring billion' some
geologists have termed it), perhaps due to chronic nutrient starvation
in the sulphidic seas. Then, something striking happened. About 1.7
billion years ago the first eukaryotic organisms appear in the fossil
record. Life had engineered the nucleus to a cell.
The Origins of Marine Diversity
Lynn Margulis (1938-2011) was one of those larger-than-life characters
who tended to shake up any scientific meeting she attended, and the
panache with which she described the sheer variousness of the micro-
scopic life she studied was quite memorable. Defying categorization
herself, she noted that life did too, especially when it came to the
question of just what is an individual organism.
Bacteria—she said in effect—really could have their cake and eat it,
although in reality the process happens the other way around. Endo-
symbiosis is the posh word for it. A large cell engulfs a smaller cell—or,
perhaps the smaller cell is trying to parasitize the larger. Whatever the
exact process, the outcome is not always the digestion and dissolution
of one by the other. The two original organisms, one inside the other,
both survive and begin to collaborate, sharing out the tasks of this new
greater whole between them. This is not murder, but cooperation—
and it opened up the world to entirely new possibilities.
Lynn Margulis, as a young scientist, had great problems getting
her idea published. It was not quite new—it had been mooted as a
theoretical possibility for the best part of a century, while she based
her thesis on observations of living organisms. Nonetheless, for the
day it was a radical, even outrageous, idea. She submitted her paper
successively to 14 journals—and received a rejection each time. The
fifteenth journal accepted it (Margulis did not lack for tenacity).
Today, this scientific battle has been won, and it is recognized as one
of the great revolutionary changes in biology. The nucleus in a cell,