Eukaryotic Life

The lower line of the geological chart in table 38-1 covers the time represented by one-eighth of the upper line-the time beginning with the Paleozoic era (600 million years ago). Near the beginning (that is, the left end) of this “ribbon,” an event of singular significance took place: the origin of eukaryotes. That event was followed by the origin of sex. From that time forward, a great number and a great diversity of forms developed.