wunder beta🧬 How Life Has Changed Over Time
From tiny microbes to dinosaurs to us, life on Earth has transformed over billions of years. Take a journey through deep time.
What you’ll learn
- Deep TimeGrasp the scale of deep time and name the great eras of Earth's history.Life on Earth began around 3.5 billion years ago, a span so vast it is called deep time. The earliest life was tiny microbes in the sea, some forming stromatolites. Scientists divide Earth's story into eras — the Precambrian, Paleozoic, Mesozoic, and Cenozoic — with the earliest chapter lasting far longer than all the rest.
- Great ChangesDescribe major milestones in life's history and place them in order.Life changed through great milestones: tiny microbes came first, then the Cambrian explosion filled the seas with new animals about 540 million years ago. Later, fish with sturdy fins gave rise to the first four-legged land animals, captured by the fossil Tiktaalik. Then came the age of dinosaurs and, after them, the age of mammals.
- Life's Big TreeExplain evolution as the driver of change and that all life shares one ancient beginning.Life keeps changing through evolution: living things pass small differences to their young, and those best suited to their world survive and pass on their traits over many generations. All living things share one ancient beginning, forming a single branching tree of life. Modern humans are recent arrivals, appearing only in the last tiny sliver of deep time.
Questions this course answers
About how long ago did the first life appear on Earth?
The first living things appeared around 3.5 billion years ago, at the start of deep time.
What was the earliest life on Earth like?
The earliest life was tiny microbes living in the sea; some built mounds called stromatolites.
What was the Cambrian explosion?
The Cambrian explosion was a burst of many new animal types in the seas about 540 million years ago.
What does the fossil Tiktaalik help show?
Tiktaalik is a 'fish with almost-legs' that captures the transition from fish to four-legged land animals.
What is evolution?
Evolution is the slow change in living things over many generations as the best-suited survive and pass on their traits.
Where do modern humans fit in the story of life?
Modern humans have existed only a few hundred thousand years — a tiny sliver at the end of life's billions-of-years story.
Grounded in trusted sources
- Natural History Museum
- Smithsonian's National Museum of Natural History
- American Museum of Natural History
- United States Geological Survey (USGS)
Every Wunder lesson is built from real, reputable sources — never invented.
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