Humans have been on Earth for a very long time.
Humans have been on Earth for a very short time.
Humans have been on Earth for a somewhat long time.
Humans have been on Earth for a somewhat short time.
Cenozoic
Mesozoic
Paleozoic
Precambrian
Cenozoic
Paleozoic
Precambrian
Mesozoic
4.6 days old
4.6 million years old
4.6 billion years old
4.6trillion years old
Precambrian
Paleozoic
Mesozoic
Cenozoic
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