However, during the Proterozoic, a large evolutionary step occurred with the appearance of eukaryotes.
Evolving around 2.1-1.6 billion years ago, eukaryotic cells are more complex with cell organelles and a nucleus with more complex DNA replication and regulation, mitochondria for additional energy, and chloroplasts to perform photosynthesis and produce energy.
Certain organelles even have their own DNA, like mitochondria. Eukaryotes are the branch of the tree of life that gave rise to fungi, plants, and animals.
About 1.2 billion years ago, another important event in Earth's biological history occurred when some eukaryotes invented reproducion.
By sharing genetic material between reproducing individuals (male and female), evolutionary change was enhanced by increasing genetic variability. This allowed more complexity among individual organisms, and eventually, ecosystems.