Final answer:
The Earth was formed approximately 4.6 billion years ago. Earliest evidence of life date to around 3.9 billion years ago, with life becoming more complex by 3.5 billion years ago.
Step-by-step explanation:
The Earth was formed approximately4.6 billion years ago. This estimation is based on the analysis of both the oldest Earth rocks and the oldest meteorites. Research indicates the Earth's early years were volatile, with numerous impacts potentially stripping the planet of its atmosphere. By the time the oldest surviving rocks were formed about 3.9 billion years ago, life already existed on Earth. The appearance of large colonies, called stromatolites, at 3.5 billion years ago, indicates that life had reached a level of sophistication. These formations still exist today, proving the resilience and adaptability of life over billions of years.
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