If we compress the entire history of the Earth into one year, life on Earth appeared

• A. In late December
• B. In mid-November
• C. In early January
• D. In early February

Answer: (D)

This uses a year-long timeline to show when events happened in Earth's history. If we imagine Earth forming on the first moment of January, life arising a little over a quarter of the way through the year places it in early February. In numbers, life likely first appeared around 3.5 to 3.8 billion years ago, which is about 1.0 to 1.1 billion years after Earth's formation. That interval is roughly 22 percent of the 4.5 billion-year history, translating to about 2.6 months into the year—early February. So the timing fits best with early February, illustrating how early life showed up soon after the planet formed, long before multicellular life and humans.