Final answer:
Humans have been on Earth for approximately 200,000 years, and human civilization is about 10,000 years old. Homo sapiens evolved in Africa and have spread across the globe, inhabiting all continents except Antarctica on a permanent large scale.
Step-by-step explanation:
How Long Have Humans Been on Earth?
Humans have been inhabitants of planet Earth for a brief time in the grand scale of its history. Homo sapiens, the species to which all present-day humans belong, emerged approximately 200,000 years ago. Initially evolving in Africa, our species faced a near-extinction event about 70,000 years ago but managed to survive, with evidence of the migration out of Africa happening by about 50,000 to 70,000 years ago. Human civilization, as we recognize it with the establishment of agriculture and permanent settlements, is roughly 10,000 years old.
If we picture Earth's 4.5-billion-year history as a single 24-hour day, humans would have appeared in the last minute of that cosmic day. Our ancestors of the genus Homo have been around for the last 2.5 million years, but only in the past 300,000 years have humans begun to look as we do now.
In summary, while the age of Earth is about 4.5 billion years and life itself began approximately 3.5 to 4 billion years ago, modern humans have only been around for a fraction of that time, evidencing our relatively recent arrival in Earth's longstanding narrative.