 |
 |
 |
 |
 |
 |
|
|
|
 • Basic Overview
Early Life Evolves
Cells joining forces formed a new type of life. Around 2.5 billion years ago, some cells began engulfing other cells. These cells were able to function together, forming a new type of cell: a eukaryote.
Eukaryotes are different from other cells (prokaryotes) because they have a nucleus, which contains the cell’s DNA, and other specialized compartments. These different compartments perform different tasks within the cell.
Every organism, living and extinct, that is not single-celled—including you—is made up of eukaryotic cells.
 At first, all eukaryotes were single-celled, and many still are today. For billions of years, these cells reproduced by splitting in two, producing two cells with nearly identical DNA.
But over time, eukaryotic cells (cells with specialized compartments) evolved that didn’t just copy themselves, but reproduced by combining part of their DNA with DNA from another cell. The offspring were not exact duplicates of their “parents,” but got half of their DNA from each parent.
This is sex—and it meant big things for evolution.
Continue to Sexual Evolution. >>
|
|
|
|
|
|
