what is evolution by stages?
Answers
The evolutionary process has developed over millions of years. Lineages evolved and split and modifications occurred gradually in stages. Life has been in existence on Earth for at least 3.5 billion years but the first two stages of evolution took place in the space of a billion years! The earliest types of cells were believed to be 'prokaryotes', cells without a special centre or nucleus, which are free-living entities. They make proteins and reproduce without the need of a plant or animal host e.g., bacteria . 'Eukaryotes' appeared between one and two billion years ago when an oxygen-rich atmosphere was present. These were cells that contain a nucleus. Eukaryotes have their DNA structures within the nucleus which are 10 to 1000 times more than those found in prokaryotes.