Summary
Highlights
Our solar system, including Earth, began forming 4.5 billion years ago from a cloud of gas and dust. Early Earth was volcanically active with an atmosphere of hydrogen sulfide, methane, and carbon dioxide. A massive collision with a Mars-sized planet named Theia created the Moon.
Around 3.8 billion years ago, Earth cooled enough for water to condense, forming primitive oceans. Life appeared 3.7 billion years ago as microscopic organisms. The first continents emerged from the ocean, followed by the supercontinent Valbara. Cyanobacteria evolved 2.4 billion years ago, producing oxygen and leading to Earth's first ice age.
Continents shifted, forming the vast supercontinent Rodinia, and life became more complex. Rodinia then broke apart, leading to the formation of Pannotia. The Cambrian explosion, around 540-485 million years ago, saw an explosion of new life forms with hard body parts, including trilobites.
Around 440 million years ago, the Ordovician-Silurian Extinction wiped out much of Earth's life. The first trees and land animals appeared 420-350 million years ago. 250 million years ago, the supercontinent Pangea formed, but it was also when the 'Great Dying' occurred, eliminating 90% of all species. This paved the way for dinosaurs, which ruled for 150 million years.
An asteroid impact 66 million years ago caused a devastating climate change, leading to the extinction of dinosaurs. Mammals then became more common. Early humans, Sahelanthropus, appeared around 6 million years ago, eventually walking upright and developing tools. The discovery of fire 800,000 years ago accelerated human brain evolution.
Homo sapiens became the sole human species between 40,000 and 15,000 years ago. Earth saw its first farmers 10,000 years ago. The Industrial Revolution 250 years ago led to major technological and societal changes. The human population has grown exponentially, exceeding 8 billion. Now, climate change poses a new threat, with rising temperatures, sea levels, and declining biodiversity, potentially leading to another mass extinction event.