Earth, 4.6-billion-years old, grew from a cloud of dust and rocks surrounding the young Sun. 4-3.5b years ago - First organisms...The oldest confirmed fossils, of single-celled microorganisms, are 3.5 billion years old. Life may have begun in warm alkaline vents on the seabed, or in open water, or on land. 3.4b years ago - Life harnesses the power of sunlight - The biggest source of energy for life on Earth is the Sun. Early microorganisms evolved photosynthesis- using energy from sunlight to make sugars out of simpler molecules.
2.4b
The Great Oxidation Event
Breathable air
For the first half of Earth's history, there was hardly any oxygen in the air. But then some bacteria began harnessing sunlight to make sugar from carbon dioxide and water, just like green plants today. These microbes pumped out oxygen as a waste product, creating the oxygen-rich atmosphere we have today.
1.2b
The first sex
Origin of mating
Between 1.8 billion and 800 million years ago, the fossil record looks fairly dull – so much so that the period is called the 'Boring Billion'. But behind the scenes plenty was happening. For one thing sex may have evolved for the first time. It's not clear why, or when, some organisms stopped simply dividing in two and started the messy business of sex.
850-635m
A frozen world
Earth froze over again, twice, in the space of 200 million years. This 2nd Snowball period may have triggered the evolution of the first complex animals.
535m
The Cambrian Explosion
Soon after animals evolved, evolution went through two major growth spurts. This apparent 'explosion' may be partly down to better fossilization, as many animals now had hard shells.
465m
Plants colonize the land
Out of the sea
Animals ventured onto land as far back as 500 million years ago, but they only visited briefly – perhaps to lay eggs in a place without predators. Plants were the first to take up permanent residence on land. The first land plants were relatives of green algae, but they rapidly diversified.
460-430m
The first mass extinction
The Ordovician period was a time when life flourished. But towards its end, the world froze dramatically as ice sheets spread from the poles leading to the 2nd-worst mass extinction on record, the Ordovician-Silurian. Most life was still confined to the sea, and 85% of marine species were wiped out.
375m
From fish fins to legs
After plants, animals moved out of the water. Insects were among the first, around 400 million years ago, soon followed big, backboned animals such as Tiktaalik, a fish that looked a bit like a salamander that eventually evolved four limbs, and gave rise to amphibians, reptiles and mammals.
320m
Dawn of the reptiles
Reptiles evolved from newt-like amphibians. Unlike their ancestors they had tough, scaly skin and laid eggs with hard shells that did not have to be left in water. They quickly became the dominant land animals.
See more in video...
Music: Forgotten Shore by Dhruva Aliman
2.4b
The Great Oxidation Event
Breathable air
For the first half of Earth's history, there was hardly any oxygen in the air. But then some bacteria began harnessing sunlight to make sugar from carbon dioxide and water, just like green plants today. These microbes pumped out oxygen as a waste product, creating the oxygen-rich atmosphere we have today.
1.2b
The first sex
Origin of mating
Between 1.8 billion and 800 million years ago, the fossil record looks fairly dull – so much so that the period is called the 'Boring Billion'. But behind the scenes plenty was happening. For one thing sex may have evolved for the first time. It's not clear why, or when, some organisms stopped simply dividing in two and started the messy business of sex.
850-635m
A frozen world
Earth froze over again, twice, in the space of 200 million years. This 2nd Snowball period may have triggered the evolution of the first complex animals.
535m
The Cambrian Explosion
Soon after animals evolved, evolution went through two major growth spurts. This apparent 'explosion' may be partly down to better fossilization, as many animals now had hard shells.
465m
Plants colonize the land
Out of the sea
Animals ventured onto land as far back as 500 million years ago, but they only visited briefly – perhaps to lay eggs in a place without predators. Plants were the first to take up permanent residence on land. The first land plants were relatives of green algae, but they rapidly diversified.
460-430m
The first mass extinction
The Ordovician period was a time when life flourished. But towards its end, the world froze dramatically as ice sheets spread from the poles leading to the 2nd-worst mass extinction on record, the Ordovician-Silurian. Most life was still confined to the sea, and 85% of marine species were wiped out.
375m
From fish fins to legs
After plants, animals moved out of the water. Insects were among the first, around 400 million years ago, soon followed big, backboned animals such as Tiktaalik, a fish that looked a bit like a salamander that eventually evolved four limbs, and gave rise to amphibians, reptiles and mammals.
320m
Dawn of the reptiles
Reptiles evolved from newt-like amphibians. Unlike their ancestors they had tough, scaly skin and laid eggs with hard shells that did not have to be left in water. They quickly became the dominant land animals.
See more in video...
Music: Forgotten Shore by Dhruva Aliman
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