How long ago were the first living things form?

Answer 1

The Earth formed about 4.5 billion years ago, and less than a billion years after that, the first forms of life are believed to have appeared. They would probably have to wait until the oceans got below 100oC. Deep sea hydrothermal vents known as 'Black smokers' would have had the conditions necessary for the formation of life.

Fossils pretty well have to wait till there are hard-skined beings suitable for preservation. About 600 million years ago.

There is a colonial organism still found today, called Stromatolites and these are regarded as evidence of one form of very early life.

Eventually the algae formed and invented photosynthesis, and this marks a very major change on Planet Earth. The oxygen they produced was toxic to many of the existing bacteria. They consumed the methane and CO2 of the early atmosphere, and caused global cooling to the extent that the Earth entered a 'Snowball Earth' phase which lasted for a billion years or so.

Finally to emerge from the cold at the early pre-Cambrian, about 600 million years ago.

Plants are thought to have developed from the green algae. Animals of primitive form had to wait until the slimes arrived to provide food.

Answer 2

The first living things are estimated to have formed around 3.5 to 3.8 billion years ago. These early life forms were likely simple single-celled organisms.