"A Timeline of Life’s Journey from the First Cell to Modern Humans."
Early Life on Earth (4.4 billion - 3.5 billion years ago)
- 4.4 billion years ago: Formation of Earth's crust and possible presence of liquid water, suggesting conditions for early life1.
- 3.8 billion years ago: End of the Late Heavy Bombardment, marking a period when life could begin to form on Earth2.
- 3.5 billion years ago: Earliest undisputed evidence of life on Earth, with fossils of single-celled organisms12.
Evolution of Complex Life (3.5 billion - 700 million years ago)
- 2.1 billion years ago: Emergence of eukaryotic cells, which are more complex and eventually give rise to multicellular life6.
- 1.5 billion years ago: Oxygen begins to accumulate in the atmosphere, paving the way for more complex life forms5.
- 1.3 billion years ago: Opisthokonts emerge, a group that includes fungi and animals6.
Animal Evolution (700 million - 6 million years ago)
- 700 million years ago: First simple animals evolve5.
- 610 million years ago: Kingdom Animalia emerges6.
- 530 million years ago: First vertebrates (fish) evolve56.
- 400 million years ago: First land plants evolve, followed by the first land vertebrates5.
Human Evolution (6 million years ago to present)
- 6 million years ago: Early human ancestors evolve with upright posture4.
- 4.1 million years ago: Broad knee joints indicate adaptation to bipedal walking4.
- 3.6 million years ago: Oldest human footprint trails found4.
- 2.6 million years ago: Early humans make basic tools4.
- 2.5 million years ago: Evidence of a double-curved spine for bipedalism4.
- 1.9 million years ago: Robust hip bones and longer thigh bones for efficient walking4.
- 1.8 million years ago: Early humans disperse from Africa to Asia4.
- 1.6 million years ago: First major technological innovation with hand axes4.
- 800,000 years ago: Control of fire and creation of hearths4.
- 300,000 years ago: Emergence of anatomically modern humans (Homo sapiens)36.
- 60,000 years ago: Modern humans begin worldwide migrations4.
- 40,000 years ago: Modern humans reach Europe4.
- 15,000 years ago: Modern humans reach the Americas4.
- 12,000 years ago: Beginning of farming and herding, leading to settlements and population growth4.
This timeline integrates the evolution of life on Earth with the specific milestones in human evolution, providing a comprehensive overview of how life evolved and eventually led to the emergence of Homo sapiens.