Life on earth?

Question

What makes Earth such a great place for life today?

what geologic evidence shows the first appearance of life on Earth and when did Earth become that "Great place" that it is today?

Answer 1

Wow God did all that! He must be really patient to spend 3.5 billion years forming us.

Answer 2

Earth is a great place for life because life adapted to the conditions as they changed. The chemistry of sediments deposited early in the history of Earth show the oxygen levels were much too low for most animal life that inhabits it now. As the composition of the atmosphere changed (due largely to the activities of organisms able to survive the original conditions) life adapted through the generations to the conditions.

Banded Iron formations over 2 billion years old contain individual algae fossils visible to the naked eye, and stromatolites (algal colonies) just over 3 1/2 billion years old are found in some places. It appears Earth was a "great place" for what we would probably call pond scum but not much else for the first few billion years after life appeared. But as the algae took in the carbon dioxide and produced oxygen, the balance changed. It appears that about the time of the so-called "Cambrian Explosion", Earth became a great place for organisms like trilobites and mollusks. As other conditions changed, it was a great place for the descendants of those earlier forms because they evolved under the pressure of the changing conditions.

Or you could just say "goddunnit" and not worry about such things as research, complex details, and critical thinking skills.

Answer 3

god!