From very simple cells, to multi-cellular human beings, life had a long way to go. A number of very important advances in evolution allowed life to become what it is today. The first important advancement was the development of cells that use oxygen. Remember, the first cells could not use oxygen because there was not enough of it in the air. However, as these first cells carried out the business of living, they released oxygen into the atmosphere. Over a very long period of time, our atmosphere changed from a poisonous and deadly mix of gases to the atmosphere we know and love today. |
As the atmosphere changed, so did life. Cells evolved that could use oxygen to carry out their bodily functions. Because oxygen is a much more efficient gas, this opened the door to larger, faster, and more complex cellular lifeforms. |
The next major evolutionary advance was the development of multi-cellular lifeforms. No longer was life limited to just one cell. Creatures began to arise that were made up of two cells, ten cells, or even thousands or billions of cells. These cells began to specialize in different jobs, some acting as hearts, others as eyes, others as brains, allowing life to become very complex.
No comments:
Post a Comment