Final answer:
Life began on Earth during the evening of December 31 on the cosmic calendar, which represents the time since the Big Bang compressed into 1 year. Geological and geochemical evidence suggests that life on Earth dates back as early as 4.1 billion years ago.
Step-by-step explanation:
On the cosmic calendar, which compresses the time since the Big Bang into 1 year, life began on Earth during the evening of December 31. This means that if the entire history of the universe is represented by a single year, human life emerged at the very end of that year. Geological and geochemical evidence suggests that life on Earth dates back as early as 4.1 billion years ago.